Beginner Seasoned
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The Guide Crops Vol. 003

Sweet Potato

in Zone 9, this week

Sweet potatoes are a warm-weather crop grown for the sweet, starchy roots that form underground. Despite the name, they are not related to regular potatoes; they belong to the morning glory family. You do not grow them from seed or from tubers. Instead you plant slips, which are rooted sprouts, set out only after all frost is past and the soil is warm. The plants send out long, trailing vines that cover the ground, so they are grown on ridges or mounds with plenty of room. Sweet potatoes need a long, hot summer (about 3 to 4 months of warm, frost-free weather) and they love heat, so the warm South, Gulf, Florida, and the desert Southwest are the best places to grow them, while cooler northern gardens are a stretch and use black plastic and fast varieties. Go easy on fertilizer, especially nitrogen, or you get lots of vine and few sweet potatoes. Dig the crop before the first frost, which kills the vines, then cure the roots somewhere warm and humid for a week or two, which heals the skins and makes them sweet, and store them warm, around 55 to 60°F. Never put sweet potatoes in the fridge or anywhere cold, which ruins them. This is the opposite of how you store regular potatoes. The young leaves are also good to eat as a cooked green. Sweet potato (Ipomoea batatas) is a warm-season, frost-tender member of the morning glory family (Convolvulaceae), not a nightshade and unrelated to the ordinary potato despite the shared name. It is grown for its swollen storage roots and planted not from seed or tubers but from slips: rooted sprouts pulled from a bedded seed root and set out only after all frost danger has passed and the soil is warm, above about 65°F. The plant is a vigorous, sprawling groundcover, running long vines that root at the nodes, and it is grown on raised ridges or mounds that drain well and give the roots room to expand. The crop needs a long, hot season, roughly 90 to 120 frost-free days, and it relishes the summer heat that stalls many other vegetables, so the warm South, Gulf, Florida, and the low deserts are its stronghold while short-season northern gardens are marginal and lean on black plastic and fast varieties. Feed sparingly and keep nitrogen low, since rich ground grows rampant vine and few roots. The crop is dug before the first frost, which kills the vines, then cured warm and humid (about 80 to 85°F at high humidity for one to two weeks) to heal the skins and turn starch to sugar, and stored warm, near 55 to 60°F. Sweet potatoes are damaged by cold and must never be refrigerated or stored below about 50 to 55°F, the opposite of white potato storage. The young leaves and shoots are also edible as a cooked green.

Sweet Potato mature plant
Fig. 01 · Sweet Potato, mature Zone 9
Mature in
90-120d
from transplant
Sunlight
Full sun
8-10 hrs daily
Water
Moderate
1 inch / week
Spacing
12 to 14 in
between plants
Soil pH
5.8-6.5
slightly acidic
Today · in your zone

What's happening right now

October 21 · Zone 9 · Stage 01 · Slip establishment

Off-season for sweet potato in zone 9.

Seasoned
Microclimate · Zone 9a vs 9b

Your zone, at a finer grain

Zone 9 averages a last frost around March 1. Within Zone 9, the colder half (9a, winters down to 20°F) runs about a week later. The warmer half (9b, winters down to 25°F) runs about a week earlier. The plant app picks your subzone from your ZIP.

SubzoneLast springFirst fallGrowing daysWinter minFruits reliably
9aMar 8Nov 24~26120-25°FYes · two seasons
9bFeb 28Nov 30~27525-30°FYes · two seasons

Averages from 8 weather stations per subzone, drawn from NOAA 1991-2020 Climate Normals. Your actual frost date can vary by up to two weeks based on elevation, proximity to water, and local topography.

Source: NOAA 1991-2020 Climate Normals Methodology
Your climate region in Zone 9
The season at a glance

Planting calendar

In Zone 9, sweet potato can be planted April through June. Harvest runs August through November.

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
plant
too cold
too cold
too cold
plant
plant
plant
too late
too late
too late
too late
too late
too cold
harvest
harvest
harvest
harvest
harvest
indoors
plant out
harvest
Above-ground cropBest planted on a waning moon
The season, mapped

Seed to garden

Grow sweet potatoes from slips, which are rooted sprouts. You can buy them as certified disease-free plants, or grow your own by half-burying a healthy sweet potato in warm, damp soil about 6 weeks ahead and pulling off the sprouts once they have roots. Plant the slips 3 to 4 inches deep, with a couple of the leaf joints buried, spacing them 12 to 14 inches apart along ridges or mounds in rows about 3 feet apart. Wait until all frost is past and the soil has warmed to about 65°F. There is nothing to start from seed indoors. In cool-summer areas, laying down black plastic warms the soil and gives you extra time.Sweet potatoes are grown from slips: rooted sprouts pulled from a bedded seed root, not from seed and not from seed-potato-style pieces. Buy certified, disease-free and weevil-free slips, or bed a healthy root in warm, moist medium about 6 weeks ahead and pull the sprouts once they have roots. Set slips 3 to 4 inches deep with two or more nodes buried, spacing them 12 to 14 inches apart on ridges or mounds in rows about 3 feet apart, once all frost danger has passed and the soil is above about 65°F (70 to 80°F is better). There is no indoor seed-starting step; the slip itself is the transplant. In short-season areas, planting through black plastic warms the soil and buys extra growing days.

  1. 01
    Sow outside
    Apr 15 - Jun 1
  2. 02
    First harvest
    From Aug 1
    90-120 days from sowing
Start method
Transplant
Soil temp
65-80°F
From seed to fruit

The growing journey

Stage 01 · Slip establishment
01
Slip establishment
Days 0-21 · current stage
The slips you planted will droop for the first few days, which is normal, then perk up and start growing new leaves once they have rooted. Not much happens above ground yet while they get established.Freshly set slips that often wilt for the first several days, then recover, green up, and put out new leaves as they root in. Little top growth happens yet; the plant is building roots. Warm soil speeds this along.
Keep the soil damp while the slips root, and water them in the afternoon if they wilt badly. Cover them if a late frost threatens, since frost kills the leaves. If a slip does not perk up after a week or so, replace it.Keep the soil evenly moist while slips root in, and shade or water in the heat of the day if they wilt hard. Protect from any late frost, which kills the tender foliage. Replace any slips that fail to take within the first week or two.
FROM PLANT · Use certified disease-free slips from a garden supplier, not sprouts from a store-bought sweet potato, which can bring in the sweet potato weevil and disease. Plant them 3 to 4 inches deep with a couple of leaf joints buried, and keep them watered while they root. It is normal for them to wilt at first.Plant only certified disease-free and weevil-free slips, not sprouts off a grocery-store root, which can carry the sweet potato weevil, viruses, and soilborne disease. Set slips 3 to 4 inches deep with two or more nodes buried, and keep them watered while they root, since early wilting is normal.
FROM PLANT · Wait until it is warm: plant slips only after all frost is past and the soil has warmed to at least 65°F, ideally 70 to 80°F. Sweet potatoes are killed by frost and sulk in cold soil, so there is no point planting early. In cool-summer areas, black plastic warms the soil and gives you more growing time.Wait for warm soil: set slips only after all frost danger has passed and the soil is above about 65°F, ideally 70 to 80°F. Sweet potatoes are frost tender and stall in cold soil, so there is no benefit to rushing. In short-season areas, black plastic mulch warms the soil and buys extra days.
02
Vine growth
Days 21-55
The plants send out long vines that spread across the ground and root where the leaf joints touch the soil, soon covering the bed in leaves. This leafy growth is building the plant that will make your sweet potatoes.Vigorous vines that begin to run and sprawl across the bed, rooting at the leaf nodes where they touch soil and quickly forming a dense groundcover. This canopy is what will feed the storage roots.
Keep weeds down until the vines spread and cover the ground, after which they smother most weeds. If the plants look weak, feed lightly with a low-nitrogen fertilizer, but do not overdo it or you will get all leaves. Water evenly.Keep the bed weeded until the vines close over and shade out weeds themselves. Side-dress lightly with a low-nitrogen feed as the vines run if growth is weak, but do not overfeed nitrogen. In small beds, you can lift and reposition vines so they do not root everywhere, though it is not essential.
FROM PLANT · Feed lightly, and go easy on nitrogen. A little low-nitrogen fertilizer like 5-10-10 as the vines spread is enough. Too much nitrogen or fresh manure grows a jungle of leaves and hardly any sweet potatoes.Feed lightly and keep nitrogen low. A light side-dressing of a low-nitrogen fertilizer such as 5-10-10 as the vines run is plenty; heavy nitrogen and fresh manure grow rampant vine and few storage roots.
FROM PLANT · Keep weeds down until the vines spread and cover the ground, after which they crowd out most weeds themselves. Once the vines are running, do not dig around the plants, which disturbs their roots.Keep the bed weeded until the vines close over, after which the dense canopy shades out most weeds on its own. Avoid deep cultivation once the vines are running, so you do not disturb the shallow feeder roots.
03
Storage root formation
Days 45-80
The vines are full and leafy above ground, and underneath, the sweet potatoes are starting to form and swell along the buried stem. You cannot see it, but this is when the plant decides how many roots it will make.Full vine cover above ground while, out of sight, the storage roots begin to swell along the buried stem. This is when the plant sets how many roots it will make, so even moisture and restrained nitrogen matter most now.
Keep the watering steady now that the sweet potatoes are starting to form, and do not add much nitrogen, which would grow leaves instead of roots. Water through dry spells but do not let the bed get soggy.Hold steady, even moisture now that roots are forming, and keep nitrogen restrained, since excess nitrogen at this stage grows vine instead of roots. Keep the bed watered through dry spells but never waterlogged.
FROM PLANT · Keep the watering steady as the sweet potatoes start to form, because this is when the plant decides how many to make. Do not add much nitrogen now, or the plant goes back to growing leaves instead of roots.Hold steady, even moisture as the storage roots begin to form, since this window sets how many roots the plant makes. Keep nitrogen restrained now, because excess nitrogen at root formation shifts the plant back toward vine.
04
Root bulking
Days 70-110
The sweet potatoes are growing bigger underground while the vines stay green and leafy. This is the most important time for a good harvest. Toward the end you can gently dig at the edge of a plant to see how big the roots are getting.Storage roots sizing up underground while the vines stay green and full. This is the critical window for yield: even moisture and warm soil now build root size and quality. You can carefully lift a plant to check root size toward the end of the window.
Keep the water steady while the sweet potatoes size up, which is the most important time, then start cutting back on water in the last couple of weeks. Hot weather actually helps now. In the South, watch for the sweet potato weevil.Keep moisture even and steady while roots bulk, the critical period for size and quality, then begin easing off water in the last couple of weeks. Warm soil favors bulking, so this is a strength in hot regions. Keep an eye out for the sweet potato weevil in the South.
FROM PLANT · Keep the watering steady while the sweet potatoes size up, about 1 inch a week, then ease off in the last couple of weeks. Letting the soil go dry and then soaking it now makes the roots crack. Warm weather actually helps them grow.Keep moisture even and moderate while roots bulk, about 1 inch per week, then taper off in the last 2 to 3 weeks. A dry-then-soaked swing now cracks and misshapes the roots, while warm soil favors good sizing.
FROM PLANT · In the South, watch for the sweet potato weevil while the roots are sizing, and keep the patch away from last year's bed and from stored sweet potatoes. You cannot fix tunneled roots, so clean slips and cleanup are what protect the crop.In the South and Gulf, scout for the sweet potato weevil during bulking and keep the crop away from last year's beds and stored roots. There is no rescue for tunneled roots, so sanitation and certified slips do the real work.
05
Maturity and harvest
Days 110-140
The sweet potatoes reach full size about 3 to 4 months after planting, and the older leaves may start to yellow. Unlike regular potatoes, the tops do not clearly die back, so you dig based on the calendar and, most importantly, before frost, because frost kills the vines and cold soil hurts the roots.Roots that have reached full size, about 90 to 120 days from transplanting, often with the oldest leaves beginning to yellow. There is no dramatic die-back signal as with potato; you harvest on days-to-maturity and, above all, before frost, since a hard frost kills the vines and cold soil damages the roots.
Stop watering as harvest nears. Dig on a dry day once the roots are big enough and before the first frost, loosening the soil with a fork well away from the plant so you do not stab the sweet potatoes. Handle them gently, let them dry off out of the sun, then cure them warm and humid before storing. If frost hits the vines, cut them off and dig within a day or two.Ease off watering as harvest nears. Dig on a dry day once roots reach size and before the first frost, loosening carefully with a fork well outside the plant so you do not spear or bruise roots. Handle them gently, let them dry briefly out of the sun, then cure warm and humid before storage. If frost catches the vines, cut them off and dig within a day or two.
FROM PLANT · Dig your sweet potatoes about 3 to 4 months after planting and before the first frost, because frost kills the vines and cold soil hurts the roots. Dig on a dry day with a fork, pushing it in well away from the plant so you do not stab them. If frost hits the vines, cut them off and dig within a day or two.Harvest on days-to-maturity (about 90 to 120 days) and before the first frost, since frost kills the vines and cold soil damages the roots and shortens storage. Dig on a dry day with a fork well outside the plant to avoid spearing roots. If frost catches the vines, cut them off and dig within a day or two.
FROM PLANT · Cure the sweet potatoes warm and humid, about 80 to 85°F and damp, for 1 to 2 weeks so the skins heal and the flesh turns sweet, then store them warm at about 55 to 60°F. Never put them in the fridge or anywhere below about 50 to 55°F, which ruins them.Cure the dug roots warm and humid, about 80 to 85°F at 85 to 90 percent humidity for 1 to 2 weeks, to heal the skins and convert starch to sugar (the step that makes them sweet), then store warm at about 55 to 60°F. Never refrigerate or store below about 50 to 55°F, which causes chilling injury.
Beginner
Know your soil

Your soil

Identify yours

Not sure what soil you have? Grab a small handful of damp soil from your garden bed and squeeze it. If it crumbles apart easily, it's sandy. If it holds together but breaks when you poke it, it's loam (what most vegetables want). If it stays in a hard, slippery ball, it's clay.

What this crop wants

Sweet potatoes want loose, well-drained, sandy or loamy soil that the swelling storage roots can push through easily. Light soil on raised ridges or mounds is ideal, because it drains well and gives the roots room to grow smooth and long. Heavy, wet clay is the thing to avoid: it stays soggy, rots the roots, and forces them into short, knobby shapes. If your soil is heavy, build up a ridge or a raised bed of loose mix, which also warms up faster in spring. Keep the soil slightly acidic, about pH 5.8 to 6.5. Go easy on nitrogen and fresh manure, which grow lots of leafy vine and few roots.

If your soil doesn't match

You have sandy soil

Mix 2-3 inches of compost into the top 6 inches of your bed before planting. Compost holds moisture (which sandy soil drains too fast) and adds the nutrients sandy soil tends to lack. Repeat each season. Compost breaks down over time.

You have clay soil

Mix 2-3 inches of compost AND a few inches of coarse sand or perlite into the top 6 inches of your bed. The compost feeds the plants; the sand breaks up the clay so air and water can move through. Don't add sand without compost. It can compact like concrete.

Containers and raised beds

If amending your soil sounds like too much work, or if your soil is heavy clay, full of rocks, or contaminated, build over it. A raised bed at least 12 inches deep filled with a 50/50 mix of compost and sandy loam gives you ideal growing soil with no battles. A 5-gallon container with quality potting mix does the same for one plant at a time. Both bypass your native soil entirely.

Learn more about your soil
The specs

Care guide

The numbers that matter, at a glance.

Sunlight
Full sun · 8-10 hrs/day
Water
Moderate
Spacing
12 to 14 inches
Soil
sandy loam, loamy sand
Days to maturity
90-120 days from transplant
Soil pH
5.8 to 6.5
Container OK?
Yes · 15+ gal pot
Germination temp
65-80°F
In a pot

Yes, 15 gallons and up

Sweet potatoes grow well in large containers, which is handy if your soil is heavy clay or you are short on space. Use a deep tub or grow bag of at least 15 gallons with drainage holes, fill it with loose mix, plant a slip or two of a compact bush variety, and let the vines trail. Keep the mix evenly moist but never soggy, feed lightly, and tip the container out to harvest when the leaves yellow or frost threatens.Sweet potatoes are well suited to a large container and a good option on heavy clay or in small spaces. Use a 15 gallon or larger tub or grow bag at least 12 inches deep with drainage holes, filled with a loose, free-draining mix; plant one or two slips of a compact bush variety (Vardaman, bush Porto Rico) and let the vines trail over the sides. Keep moisture even but never waterlogged, feed only lightly to avoid all-vine growth, and harvest by tipping out the container when foliage yellows or frost approaches.

Pot size
15 gallons and up; 20 gallons is comfortable
Mature size
12 inches tall
Drainage
Drainage holes are a must. Skip the gravel layer. Do not let the pot sit in a tray of water. Soggy soil rots sweet potatoes, so make sure the water drains out and empty the saucer after you water.Drainage holes are a must. Skip the gravel layer. Do not let the container stand in a saucer of water. Sweet potatoes rot in waterlogged mix, so ensure free drainage and empty any saucer after watering.
Watering
Containers dry out faster than the ground, so check daily in warm weather and keep the mix evenly moist while the sweet potatoes are forming. Do not let it swing between bone-dry and soaked, which makes the roots crack, and never let it stay waterlogged.Containers dry far faster than beds, so check the top inch or two daily in warm weather and water to keep the mix evenly moist but never waterlogged, since sweet potatoes rot in a saturated pot and crack under a dry-then-soaked cycle.
Depth and shape
At least 12 inches deep. Volume and depth matter, and so does room for the vines to spill over the sides. Use a large tub or grow bag of at least 15 gallons (20 or more is better) and at least 12 inches deep, so the storage roots have room to form. Choose a compact bush variety such as Vardaman or a bush Porto Rico for containers; full-size vining types quickly outgrow a pot. Fabric grow bags drain and aerate well and make harvest easy, since you simply tip them out.
Self-watering pot
A self-watering container can help hold the even moisture sweet potatoes want during root bulking, but it must drain freely: sweet potatoes rot in a constantly saturated reservoir, so use it carefully, never let the mix stay waterlogged, and choose a deep, roomy container and a bush variety.
Mix
Container potting mix. Use a light, free-draining potting mix amended with compost and only a modest, low-nitrogen fertilizer. Avoid heavy garden soil, which compacts and waterlogs in a container, and avoid rich nitrogen, which grows vine at the expense of roots.
Feeding
Frequent watering leaches nutrients from a container, but keep feeding restrained: incorporate a modest low-nitrogen fertilizer at planting and feed sparingly during growth, since excess nitrogen in a pot grows rampant vine and few roots.
Pot safety

Ask what your balcony or roof can carry

A balcony or roof can only hold so much weight. Before you set heavy pots there, ask a building architect what it can safely carry.Illinois Extension's guidance is to consult a building architect about weight limits before placing heavy pots on a balcony or rooftop garden. It gives no weight figure.

Never grow food in a container with anything toxic in it

Many kinds of containers can be used. Whatever you choose, keep anything toxic out of it, especially if you are growing food.Colorado State accepts nearly any container material but warns against using a container that holds toxic materials, especially for edible plants. Illinois adds that a vegetable container should be free of chemicals toxic to plants or people, and urges caution with treated lumber when growing food. If you cannot account for what a repurposed container once held, that alone is a reason to keep food out of it.

Secure hanging containers well

Fasten hanging baskets and window or rail boxes securely. Think about what is below them too, since they can drip on people or things underneath.Illinois Extension asks growers to secure hanging containers well and to think through the safety issues of hanging them. Placement matters too, since a hanging container can drip onto people or belongings below.

Soil chemistry

Soil pH for sweet potato

Preferred
5.8 to 6.5
Tolerated
5 to 6.8

Soil pH measures how acidic or alkaline your soil is, on a scale from 1 to 14 where 7 is neutral. Sweet potatoes like it slightly acidic, about 5.8 to 6.5, which is close to what most vegetables want. They are not fussy and will grow from about 5.0 up to nearly neutral, so you rarely need to change your soil much. A cheap soil test from your local extension office tells you your number, and if your soil is very alkaline, mixing in compost helps. Do not overdo lime.Sweet potatoes grow best in slightly acidic soil, roughly pH 5.8 to 6.5 (University of Georgia gives 6.0 to 6.5). They are adaptable and will crop from about 5.0 up toward neutral, so pH is rarely the limiting factor. Where soil pox and Streptomyces soil rot are a problem on susceptible varieties, growers avoid pushing the pH high and lean on resistant cultivars rather than heavy liming. Amend very alkaline ground with organic matter and confirm your starting point with a soil test before planting.

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Steady hand on the hose

Watering

When & how much
Frequency
Keep the soil evenly, moderately damp, especially right after planting the slips and later while the sweet potatoes are sizing up. Give about 1 inch of water a week, counting rain, in fewer but deeper waterings. Once the vines are growing well the plants handle dry spells fairly well, but letting the soil go dry and then soaking it while the roots form makes them crack. Cut back on water in the last few weeks before you dig.Sweet potatoes want even, moderate moisture, especially while the slips establish and again while the storage roots are sizing. Aim for about 1 inch of water per week including rain, delivered in deeper, less frequent soakings. Once well established the deep root system makes them fairly drought tolerant, but a prolonged dry-then-wet swing during root bulking causes cracked and misshapen roots. Ease off water in the last few weeks before harvest so the roots do not split and the skins firm up.
Amount
About 1 inch of water a week, counting rain, and a bit more in hot or sandy conditions. Water most attentively right after planting and while the roots are sizing. Ease off in the last couple of weeks before harvest so the sweet potatoes do not split.About 1 inch per week including rainfall, more in heat or sandy soil, concentrated at establishment and during root bulking. Do not keep the ridge waterlogged. Taper off in the last 2 to 3 weeks before harvest to reduce cracking and let the skins set.
Method
Water at the soil, keeping the ridge damp but not soggy. A layer of mulch early on helps hold steady moisture and keep weeds down until the vines spread out and shade the ground themselves.Water at the base with a soaker hose or drip line where practical, and keep the raised ridge moist but never waterlogged. A mulch helps hold even moisture and smother weeds while the vines fill in, though the sprawling canopy soon shades the ground itself.
Signs of trouble
Too much water
If the soil stays soaking wet, the sweet potatoes rot. Watch for yellowing, wilting even though the soil is wet, a sour-smelling soggy bed, and soft or split roots; if you see these, water less and fix the drainage.Constantly saturated soil rots the roots and drives soft rot and black rot; yellowing, wilting despite wet soil, a sour waterlogged ridge, and soft or cracked roots are signs to back off and improve drainage. Waterlogging is worse than short drought for this crop.
Too little water
Droopy leaves in the afternoon, dull color, and slow growth mean the plants are thirsty, which matters most just after planting and while the roots size up. The bigger problem is letting the soil go dry and then flooding it, which cracks the sweet potatoes.Wilting in the heat of the day, dull, small foliage, and slow vine growth signal too little water, most critical during establishment and root sizing. The sharper risk is an irregular dry-then-soaked cycle during bulking, which cracks and misshapes the roots.
Feeding rhythm

Feeding

Frequency
Low
Type
Low nitrogen, higher potassium
When to start
Work a low-nitrogen fertilizer into the ridge before planting; side-dress once about 4 to 6 weeks after setting slips, as the vines begin to run.

Sweet potatoes do not need much feeding, and too much of the wrong kind backfires. Mix a low-nitrogen fertilizer like 5-10-10 into the ridge before you plant, then feed once more about a month after setting the slips. Do not pile on high-nitrogen fertilizer or fresh manure: that grows a jungle of leafy vine and hardly any sweet potatoes underneath. A little compost worked into the bed is the safe way to enrich it.Sweet potatoes are light feeders and specifically want restrained nitrogen. University of Georgia suggests working in about 30 pounds of 5-10-10 per 1,000 square feet before planting, then side-dressing roughly 4 pounds of 5-10-10 per 100 feet of row about 4 to 6 weeks after transplanting. Favor a low-nitrogen, higher-potassium ratio: too much nitrogen (and fresh manure) grows lush, sprawling vine and few storage roots, while adequate potassium supports root sizing and quality.

N · P · K = 5-10-10

The three numbers on a fertilizer bag are nitrogen, phosphorus, and potassium (N-P-K). Sweet potatoes do best with a low first number, like 5-10-10, not a high-nitrogen feed. Too much nitrogen grows leaves and vines instead of sweet potatoes, so use a low-nitrogen fertilizer and some compost.Sweet potatoes are light feeders that want low nitrogen and good potassium. A blend such as 5-10-10 worked into the ridge before planting covers most home soils. Excess nitrogen drives vine at the expense of roots, and fresh manure has the same effect, so lean on a low-nitrogen fertilizer and compost rather than a balanced or high-nitrogen feed.

Try 5-10-10
Who grows well together

Companion planting

Sweet potatoes are easygoing and take up a lot of ground with their sprawling vines, so companions are mostly about using the edges of the bed. Bush beans and other legumes are a sensible neighbor because they add nitrogen to the soil. The main thing to avoid is crowding them next to other sprawling vine crops like squash and pumpkins, which fight for the same space and sunlight. Do not trust every companion chart online; many of their claims have never been tested. Sweet potatoes are undemanding neighbors but greedy for space, since a single plant can run vines many feet in every direction. The best-grounded pairing is with legumes (bush beans, southern peas), which fix nitrogen and share the bed without heavy competition. Aromatic herbs are a traditional edge planting. The clearest practical avoids are other rampant vine crops, squash, pumpkins, and melons, which compete for the same ground and light. Most companion-chart claims for sweet potato are folklore; treat them with healthy skepticism, since university reviews find little evidence behind most of them.

Other
Bush beans
Beans are legumes that pull nitrogen from the air and leave some in the soil, which suits sweet potatoes since they want only modest nitrogen. Bush beans stay compact and can share the edge of the bed without fighting the vines for space.Bush beans and other legumes are a sensible sweet potato neighbor: they fix nitrogen and, being compact and upright, do not compete hard with the ground-running vines. The nitrogen contribution is a real mechanism; treat the pairing as a grounded tradition rather than a measured yield effect. Traditional
Aromatic herbs (dill, summer savory)
Some gardeners plant strong-smelling herbs around the edge of the sweet potato patch in the hope of confusing pests. It is a traditional idea rather than a proven one, but the herbs use the border space the vines do not need early on.Aromatic herbs at the border are a traditional pest-confusion planting with no controlled evidence behind it for sweet potato. Recorded as hedged tradition; the concrete value is filling edge space the vines reach only later in the season. Traditional
Keep apart from
Squash, pumpkins, and melons These are all big, sprawling vine crops, just like sweet potatoes. Grown side by side they smother each other and fight for the same sunlight and ground, so give each its own space in the garden.Cucurbits (squash, pumpkins, melons) are rampant ground-running vines like sweet potato, so interplanting them means two sprawling crops competing for the same ground and light. This is a habit-based space conflict, not a shared-disease risk, and the fix is simply separate beds. Traditional
Other sprawling vine crops Squash, pumpkins, and melons run vigorous ground vines that collide with sweet potato's own sprawl, shading and crowding both. Keep rampant vine crops in separate beds; this is a space-and-light conflict rather than a shared pest or disease problem. Traditional
Provenance tagged inline · see methodology for the labeling system Key
Harvest signals

When to pick

You harvest sweet potatoes by the calendar and, most importantly, before frost, not by watching the tops die back. They are usually ready about 3 to 4 months after planting, when the roots are full size; the older leaves may yellow, but unlike regular potatoes the vines do not obviously die down. Dig before the first fall frost, because frost kills the vines and cold soil hurts the roots. Loosen the soil with a fork well away from the plant so you do not stab the sweet potatoes, lift them gently, and handle them carefully because they bruise easily and the skins are thin at first. Let them dry off out of the sun, do not wash them, then cure them somewhere warm and humid for a week or two before storing. If frost hits the vines, cut them off and dig within a day or two.Sweet potatoes are harvested by days-to-maturity and, above all, before frost, not by a die-back signal. The crop is usually ready about 90 to 120 days from transplanting slips, when the roots have reached full size; the oldest leaves may yellow, but the vines do not clearly die back the way potato tops do. Dig before the first fall frost, since frost kills the vines and cold soil damages the roots and shortens storage. Loosen the soil with a fork well outside the plant so you do not spear or bruise the roots, lift them gently, and handle them carefully, since sweet potatoes bruise easily and skins are thin at harvest. Let them dry briefly out of direct sun, do not wash them, then cure warm and humid, about 80 to 85°F for one to two weeks, before storing. If a frost catches the vines, cut them off and dig within a day or two so rot does not travel down into the roots.

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Yield

What to expect

About 3 to 6 sweet potatoes, roughly 1 to 2 pounds, from each plant when things go well, though it varies a lot with the variety and the season. A row gives you something like a pound or more per foot on a good site.Roughly 3 to 6 storage roots, about 1 to 2 pounds, per plant in good conditions, varying widely with variety, season length, and care. By the row, a home crop often runs about 1 to 1.5 pounds per foot of row on a good site.

A sweet potato planting is ready all at once, about 3 to 4 months after planting, and you dig it when the roots are sized and before frost. It does not keep producing after that, so cure and store the crop, which lasts for months.A sweet potato planting matures over a single window, about 90 to 120 days, and is dug once when the roots reach size and before frost. It is not a repeat-harvest crop; for a longer supply, cure and store the crop, which keeps for months, or in frost-free regions stagger plantings. Sweet potatoes are grown fresh each year from slips, so your first crop can do as well as any later one. What matters is good slips, a long warm season, loose well-drained ridges, steady water, and going easy on nitrogen.Sweet potatoes are grown fresh from slips each season, so there is no first-year-versus-later difference as with perennials; results depend on certified slips, a long warm season, loose well-drained ridges, even moisture, and restrained nitrogen.

What changes yield
Season length and warmth: sweet potatoes need about 90 or more warm, frost-free days, and a short or cool season caps yield.Nitrogen balance: excess nitrogen grows vine at the expense of storage roots.Even moisture during bulking: drought-then-flood cycles cut yield and crack the roots.Certified, disease-free and weevil-free slips: virus or weevil brought in on slips undercuts the crop from the start.Well-drained ridges: waterlogged, heavy soil rots roots and forces short, knobby shapes.
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Pick your variety

Recommended varieties

Pick a variety for your area and how long your season is. In cooler, shorter-season gardens, choose the fastest kinds (Georgia Jet, Beauregard, Centennial) and warm the soil with black plastic. Where summers are long, bigger keepers like Jewel and Covington do well and store for months. If nematodes are a problem, pick a resistant variety like Covington or Centennial. For a pot or a small bed, the compact bush type Vardaman is ideal. There are also white, purple-skinned Japanese, and purple-fleshed types to try. Always buy certified disease-free slips, not sprouts off a grocery-store sweet potato.Choose by maturity and your climate. In short-season and northern gardens, lean on the fastest orange types (Georgia Jet, Beauregard, Centennial) and warm the soil with black plastic. Where the season is long, higher-yielding keepers like Jewel and Covington size up and store well. Covington and Centennial carry useful root-knot nematode resistance, and Sumor is a Fusarium-wilt-resistant option where that disease occurs. For containers or tight beds, the compact bush type Vardaman saves space. Beyond the standard orange types, there are pale-fleshed heirlooms, purple-skinned Japanese types (Murasaki), and deep-purple-fleshed varieties. Always start from certified disease-free and weevil-free slips.

Beauregard
Orange-fleshed, fast and high-yielding (about 90 to 100 days), widely adapted and a reliable first choice.
Covington
Orange, rose-skinned, excellent storage and root-knot nematode resistance (about 95 to 110 days).
Centennial
Classic orange, root-knot nematode and wireworm tolerant, good for shorter seasons (about 90 to 110 days).
Georgia Jet
Very fast (about 90 to 100 days), a top pick for short northern seasons.
Jewel illustration
Jewel
High-yielding orange keeper, longer season (about 120 to 135 days).
Vardaman
Compact bush habit, space-saving and good for containers (about 100 days).
Murasaki and other Japanese types
Purple skin, pale flesh, nutty flavor, nematode resistant (about 100 to 120 days).
O'Henry
Creamy white-fleshed sport of Beauregard.
Off the vine

Storing your harvest

Room temp
After curing, keep sweet potatoes in a cool but not cold spot, ideally around 55 to 60°F, in the dark with some airflow, where they last for months. A normal warm room is fine for a couple of weeks but shortens their life, so keep a few on the counter and store the rest somewhere cooler like a pantry or cellar.Once cured, sweet potatoes are best kept at warm room-to-cellar temperatures, roughly 55 to 60°F in a dark, well-ventilated spot, where they hold for months. Ordinary heated-room temperatures (68 to 75°F) are fine for a few weeks but shorten storage and can encourage sprouting; keep only what you will use soon on the counter and store the rest in a cooler pantry or cellar.
Fridge
Keep sweet potatoes out of the fridge. When they get colder than about 50 to 55°F they get damaged: they taste off, stay hard in the middle even after cooking, and rot faster. This is different from most vegetables. Store them in a cool pantry or cellar around 55 to 60°F instead, never the refrigerator.Do not refrigerate sweet potatoes. Below about 50 to 55°F they suffer chilling injury: the flesh develops off-flavors, hard cores that will not soften when cooked, internal browning, and a greater tendency to rot. This is the opposite of many vegetables. A cool pantry or cellar near 55 to 60°F, never the refrigerator, is the right place for raw sweet potatoes.
Freezer
Do not freeze raw sweet potatoes. Freeze them only after cooking, like baked or mashed, and they keep for several months.Raw sweet potatoes do not freeze well. Freeze only after cooking (baked, mashed, or as prepared dishes), where they keep for several months.
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When something goes wrong

Common problems

Big vines but few sweet potatoesLots of vine but few sweet potatoes
01 of 05
What happened The plants made a jungle of leafy vine but few sweet potatoes. This usually comes from too much nitrogen, over-rich soil, too much shade, or a season too short and cool for the roots to size up.The plants grew lush, sprawling vine but set few or small storage roots. The usual causes are too much nitrogen (which favors foliage over roots), overly rich or heavily manured soil, too much shade, or a season too short and cool for roots to bulk. Next season Use less nitrogen and a low-nitrogen fertilizer like 5-10-10, skip fresh manure, give full sun, and grow on ridges. In cooler areas, warm the soil with black plastic and pick a fast variety so the roots have time to grow.Cut nitrogen and use a low-nitrogen feed such as 5-10-10, avoid fresh manure, give full sun, and grow on ridges. In short-season areas, warm the soil with black plastic and choose a fast variety so roots have time to bulk.
Cracked or lumpy sweet potatoesCracked, knobby, misshapen roots
02 of 05
What happened The sweet potatoes came out cracked or lumpy because their growth started and stopped, usually from the soil going dry and then wet again, from heavy clay they could not grow through smoothly, or from root-knot nematodes.Roots grew cracked, knobby, or misshapen from a stop-and-start growth pattern: a dry spell followed by a surge of water, heavy clay soil that resists smooth expansion, or root-knot nematode galling. Uneven moisture during bulking is the most common cause. Next season Keep the watering steady while the roots grow and ease off before harvest, loosen heavy soil with compost or grow on ridges, and use a nematode-resistant variety if knots and cracks keep happening.Hold even moisture through bulking and taper off before harvest, loosen heavy soil with organic matter or grow on ridges and raised beds, and use nematode-resistant varieties where galling is the cause.
Sweet potatoes went bad in storageOff-flavor, hard core, or rot in storage
03 of 05
What happened The sweet potatoes tasted off, stayed hard in the middle even after cooking, or rotted in storage. This usually happens when they were kept too cold (like in the fridge) below about 50 to 55°F, or were not cured warm and humid first.Stored roots developed off-flavors, hard cores that would not soften when cooked, internal browning, or rot. The usual cause is chilling injury from storing (or refrigerating) below about 50 to 55°F, or skipping the warm, humid curing step that heals skins and sets a protective layer. Next season Cure the roots warm and humid (about 80 to 85°F) for 1 to 2 weeks right after digging, then store them around 55 to 60°F in the dark. Never put them in the fridge or anywhere below about 50 to 55°F, and do not store damaged ones.Cure warm and humid (about 80 to 85°F, 85 to 90 percent humidity) for 1 to 2 weeks right after harvest, then store at about 55 to 60°F in the dark. Never refrigerate or store below about 50 to 55°F, and do not store bruised or diseased roots.
Tunneled, bitter sweet potatoesTunneled, bitter roots (sweet potato weevil)
04 of 05
What happened The sweet potatoes were full of small holes and dark tunnels and tasted bitter, even the parts that looked okay. That is the sweet potato weevil, whose grubs tunnel the roots and make them bitter. It is the worst sweet potato pest, especially in the South.Roots came up riddled with small holes and dark, spongy tunnels, with a bitter taste and off odor even where damage looked light. This is the sweet potato weevil, whose larvae mine the roots and induce bitter terpenes; it is the most serious sweet potato pest, worst in the South and Gulf. Next season Plant certified weevil-free slips, move the patch far from last year's bed and from where you store sweet potatoes, and clean up every leftover root after digging, because the weevil lives on in them. Harvest on time.Start with certified weevil-free slips, rotate well away from last year's beds and from stored roots, and remove every cull and volunteer root after harvest, since the weevil survives in them. Harvest promptly rather than leaving roots in infested soil.
Sweet potatoes stayed smallSmall roots from too short a season
05 of 05
What happened The sweet potatoes stayed small because the warm season was too short: cold soil at planting, a late start, a cool summer, or an early frost gave them too little time to size up. This is common in cooler northern and coastal gardens.Roots stayed small because the warm-season window was too short: slips set into cold soil, a late start, a cool summer, or an early frost cut the growing period below the 90 or more warm days the crop needs to bulk. This is the common outcome in marginal northern and cool-coastal gardens. Next season Pick the fastest varieties (Georgia Jet, Beauregard, Centennial), warm the soil with black plastic, plant as soon as the soil is truly warm, and use the sunniest, most sheltered spot to give them the longest possible season.Choose the fastest varieties (Georgia Jet, Beauregard, Centennial), warm the soil with black plastic, plant as soon as the soil is reliably warm, and give the sunniest, most sheltered spot to stretch the effective season.
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The usual suspects

Pests & diseases

Pests
Sweet potato weevil
P · 01
Symptoms Small holes and dark, spongy tunnels inside the sweet potatoes, which you usually find only when you dig or slice them. Even a little feeding makes the roots taste bitter and smell off, so they are no longer good to eat. The beetle itself is a slim, ant-like weevil with a long snout, reddish legs, and a shiny blue-black body. It is the worst sweet potato pest, especially in the Deep South.Small holes and dark, spongy tunnels running through the storage roots, found when you dig or cut them. Even light feeding triggers a chemical reaction that gives the roots a bitter taste and an off, turpentine-like odor, ruining them for eating. The adult is a slender, ant-like weevil, about a quarter inch long, with a dark head and snout, reddish legs, and a metallic blue-black body; you may see chewing on stems and leaves. This is the single most serious pest of sweet potato, worst in the Deep South and Gulf. Cause A small weevil called the sweet potato weevil. Its grubs tunnel through the sweet potatoes and stems, and the plant reacts by turning bitter, so even lightly damaged roots are ruined. It rides in on infested slips and survives in leftover sweet potatoes in the ground, and it keeps damaging the crop even after harvest in storage.The sweet potato weevil (Cylas formicarius, family Brentidae). Larvae do the principal damage by mining tunnels through the storage roots (and stems), leaving them riddled with cavities, spongy, and darkened; the feeding induces bitter terpenes even at low levels. It breeds continuously in warm climates, spreads mainly on infested slips and in leftover roots, and continues to damage the crop in storage. Organic treatment You cannot fix sweet potatoes that are already tunneled, so throw them out. The whole game is prevention: plant only certified weevil-free slips, and clean up every leftover or volunteer sweet potato in the ground after harvest, because the weevil lives on in them. Dig your crop on time instead of leaving it in the soil, and do not plant next to last year's bed.There is no rescue for tunneled roots; discard them. Control is prevention: start only with certified weevil-free slips, and practice strict sanitation, removing and destroying every leftover, cull, and volunteer root that can harbor the weevil between crops. Harvest promptly once the crop matures rather than leaving roots in infested soil, and keep new plantings away from last year's beds and from stored roots. Prevention Start with certified weevil-free slips, not saved sweet potatoes. Move the patch to a new spot each year, well away from where sweet potatoes grew before and away from where you store them. After you dig, clean up every leftover and volunteer root, because the weevil survives in them. Harvest on time rather than leaving the crop in the ground.Buy certified, weevil-free slips rather than saving your own or using field-run roots. Rotate sweet potatoes well away from last year's beds and from any sweet potato storage, since the weevil moves only short distances. Remove all volunteer and cull roots after harvest, harvest promptly, and in badly infested areas grow on a strict rotation with a fallow break. Certified slips plus sanitation carry nearly all of the control.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Garden sanitation

    After you dig, go back over the bed and collect the roots you missed, the culls you set aside, and any volunteers, meaning plants that sprout on their own from a root left behind. Destroy the lot rather than leaving it in the ground, because the weevil keeps living and breeding in those roots between crops. Sweet potatoes that are already tunneled cannot be salvaged, so they go out with them.Left-behind, cull and volunteer roots are the reservoir that carries this weevil from one crop to the next, so stripping them out is most of the control that is actually available. Tunneled roots have no rescue: larval mining induces the bitter terpenes even at low feeding levels, so grade them out and destroy them rather than holding them back.

  2. Crop rotation

    Put the new patch on fresh ground, away from last season's bed and away from wherever you keep sweet potatoes stored. The weevil travels only short distances on its own, so distance from both of those sources buys you real protection. Where it is a bad problem locally, keep to a strict rotation and give the ground a fallow break.Site the planting at a distance from both the previous bed and any sweet potato storage, since the adult disperses only short distances and spreads mainly on infested slips and in roots left in the soil. Under heavy regional pressure the guidance is a strict rotation with a fallow break rather than a one-bed shuffle.

  3. Prompt harvest

    Dig the crop as soon as it is mature instead of letting it sit in the ground. Each extra week in infested soil is more time for the grubs to bore into roots you meant to eat.Lift at maturity rather than holding the crop in the bed. Feeding accumulates for as long as the roots stay in infested soil, and the weevil breeds continuously in warm climates, so the length of that exposure is the variable you control.

No spray for this one. Prevention is the control.

Wireworms and root-feeding beetle larvae
P · 02
Symptoms Narrow holes and shallow tracks drilled into the sweet potatoes, found when you dig them. They are made by hard, shiny soil worms (wireworms) and the grubs of cucumber and flea beetles. You do not see anything above ground; you find the little tunnels and pits at harvest, and damaged roots do not store as well.Narrow holes and shallow, winding grooves bored straight into the storage roots, leaving pinhole punctures and tracks that downgrade quality and open the door to storage rots. The culprits are slender, shiny, hard-bodied wireworms (click beetle larvae) plus the larvae of cucumber beetles and flea beetles (the wireworm, Diabrotica, Systena complex). There are no useful aboveground signs; the damage is found at harvest. Cause Wireworms are the larvae of click beetles; they live in the soil for years and are worst in beds that were lawn, grass, or corn not long ago. The larvae of cucumber beetles and flea beetles do similar damage, moving into the soil to nibble the sweet potatoes as they grow.Wireworms are click beetle larvae that live in the soil for several years and are most numerous in ground recently in sod, grass, or corn. The same root-scarring complex includes larvae of spotted and banded cucumber beetles (Diabrotica) and flea beetles (Systena), which move into the soil to feed on the developing roots through the season. Organic treatment You cannot fix roots that are already tunneled, so cut out the bad spots and eat those first instead of storing them. Dig the crop on time rather than leaving it in the ground, where the worms keep boring, and keep grassy weeds down.There is no rescue for scarred roots; trim damaged areas and use those roots first rather than storing them. Harvest promptly once the crop matures rather than leaving roots in infested soil, where feeding accumulates. Keeping the ground worked and free of grassy weeds reduces the habitat these larvae favor. Prevention Do not plant sweet potatoes in a bed that was grass, lawn, or corn in the last year or two, where wireworms are worst. Rotate your crops, work the soil, pull grassy weeds, and dig on time. If wireworms keep ruining a bed, use a raised bed with clean soil.Avoid planting sweet potatoes in ground that was recently pasture, lawn, or corn, where wireworm numbers peak; extend the interval between grass and a root crop. Rotate, keep the soil well worked, control grassy weeds, and harvest on time. Where wireworm history is bad, grow elsewhere or in clean raised-bed soil.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Crop rotation

    Keep sweet potatoes out of a bed that was lawn, pasture, or corn in the last year or two. That is where wireworms, the hard shiny larvae of click beetles, are thickest, and the grubs of cucumber beetles and flea beetles chew the roots in much the same way. Rotate the patch around the garden, and if one bed keeps giving you scarred roots, grow the crop elsewhere or in a raised bed of clean soil.Wireworm populations peak in ground recently out of sod, pasture or corn, so lengthen the interval between grass and a root crop instead of following one with the other. Diabrotica and Systena larvae work the same roots alongside them. Where a bed has a bad history, move the planting off it or use clean raised-bed soil.

  2. Clearing the weeds that host it

    Pull the grassy weeds in the bed and along its edges. Grass is the cover these soil grubs favor, so taking it out makes the ground less hospitable to them.Grassy weeds sustain the habitat this larval complex prefers, so clearing them from the bed and its margins removes standing cover next to the developing roots.

  3. Prompt harvest

    Dig on time rather than leaving the crop in the ground to size up a little more. The boring keeps adding up for as long as the roots sit in soil that holds these grubs, and pitted roots do not keep well afterward.Damage accumulates with time in infested ground, so lifting at maturity caps it. It also matters for what follows, since the punctures and grooves are openings the storage rots use.

  4. Off-season tillage

    Work the bed over once the crop is out, and keep working it in the seasons that follow. Wireworms stay down in the soil for years, so treat this as something you do repeatedly rather than a single pass that settles it. Working the soil has costs of its own, so see this method's cautions before making it a habit in a no-dig bed.Cultivation breaks up the soil habitat these larvae occupy. Wireworms persist in the ground across several years, so this is a multi-season lever, and it works alongside keeping the grassy cover down rather than in place of it.

No spray for this one. Prevention is the control.

Flea beetles
P · 03
Symptoms Lots of tiny holes in the leaves, as if peppered with shot, made by little dark beetles that hop away when you come near. Young slips are hurt most; big, healthy vines shrug it off. The grubs in the soil can also scar the sweet potatoes.Tiny dark beetles that jump when disturbed and chew many small round shot-holes in the leaves. Heavy early feeding on young transplants stunts growth; the soil-dwelling larvae also scar the developing storage roots. Established, vigorously running plants usually outgrow light foliage feeding. Cause Small beetles called flea beetles that spend winter nearby and jump onto young sweet potato plants. They do the most harm to freshly set slips and in warm, dry spells, and their grubs can scar the roots underground.Several species of small flea beetles that overwinter nearby and move onto young sweet potato foliage in spring and early summer. They are worst on small, slow transplants and in warm, dry weather; their larvae contribute to the root-scarring complex below ground. Organic treatment Keep young slips growing strong with steady water and they usually outgrow the damage as the vines take off. A row cover protects them early on, and clearing weeds and old plant debris takes away their winter hiding spots.Healthy, well-watered transplants usually outgrow flea beetle feeding once the vines run. Floating row cover protects young plants during the vulnerable first weeks; remove it as the vines begin to sprawl. Clearing weeds and old crop debris reduces the shelter they overwinter in. Prevention Move the patch to a new spot, pull weeds, and cover the young slips until they are established and the vines start to run. Plants that are well watered handle flea beetles much better than struggling ones.Rotate away from last year's beds, keep the area weed-free, and protect freshly set slips with row cover until they are established and running. Vigorous, evenly watered transplants tolerate feeding far better than stressed ones.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Crop rotation

    Start the patch somewhere other than last year's sweet potato bed. These beetles pass the winter close to where they fed, so fresh ground means fewer of them finding your slips in spring.Adults overwinter nearby and move onto young foliage in spring and early summer, so siting the planting away from the previous bed lowers the number arriving on freshly set slips.

  2. Garden sanitation

    Clear the spent vines and old crop debris out at the end of the season. That leftover growth is what the beetles shelter in over winter.Crop residue left standing in the bed is overwintering shelter, so a clean-up once the vines are finished cuts how many adults are on hand when the next planting goes out.

  3. Clearing the weeds that host it

    Keep the weeds down in the bed and around its edges through the season. Weedy cover gives flea beetles somewhere to hole up, so a clean edge makes the patch less inviting.Weeds are named alongside crop debris as the shelter this pest carries over in, so clear the ground before slips go in and hold the margins clean afterward.

  4. Floating row cover

    Cover freshly set slips with a floating row cover, a light fabric that lets sun and rain through while keeping insects off. Leave it on through the first weeks, when the peppering of small round holes does the most harm to a small plant, and take it off as the vines start to sprawl. Slips kept well watered and growing strongly tend to shrug off the leaf feeding once they are running.Cover at transplanting and hold it through establishment, the window when shot-hole feeding on limited leaf area actually stunts the plant, then pull it as the vines begin to run. Vigorous, evenly watered transplants tolerate the same beetle numbers far better than stressed ones, which is why the cover is a temporary measure. Avoid laying it over ground that carried a crop from the same family last season, or emerging soil pests can be trapped underneath with the planting.

No spray for this one. Prevention is the control.

Whiteflies and the viruses they spread
P · 04
Symptoms Tiny white flying insects that scatter in a cloud when you brush the leaves, clustered underneath with a sticky film. Their feeding is minor, but they can pass on plant viruses that mottle and curl the leaves and cut your harvest. A plant that catches a virus will not get better.Clouds of tiny white, moth-like insects that lift off the foliage when disturbed, clustered on leaf undersides with sticky honeydew and sooty mold. The bigger problem is not their feeding but the viruses they transmit (such as sweet potato feathery mottle virus and sweet potato leaf curl virus), which mottle, curl, and stunt the foliage and erode yield over time; virus-infected plants do not recover. Cause Whiteflies are tiny sap-sucking insects, and as they move from plant to plant they carry sweet potato viruses. The viruses, more than the bugs, are the real concern, which is why it is best to plant certified, disease-tested slips instead of saving your own.Whiteflies colonize sweet potato foliage and, as they move plant to plant, transmit sweet potato viruses. Virus pressure, not the feeding itself, is the main reason to manage them, and it is the reason growers are advised to start from certified, virus-tested slips rather than saved or field-run material. Organic treatment Plant certified, disease-tested slips so the patch starts clean. A few whiteflies are fine, because helpful bugs usually keep them in check; for heavy clusters, spray them off with water or use insecticidal soap. Pull and throw away any plant that clearly has a virus.Start with certified, virus-tested slips to keep virus out of the patch. Tolerate light whitefly numbers, since beneficial insects often control them; a strong spray of water or insecticidal soap knocks down heavy colonies on the leaf undersides. Remove and destroy any plant showing clear virus symptoms. Prevention Buy certified slips, avoid harsh sprays that kill the helpful bugs, keep weeds down, and pull out any virus-looking plant right away. Do not save slips from a patch that had virus, because it comes back with them.Use certified slips, encourage beneficial insects by avoiding broad-spectrum sprays, control nearby weeds that host whiteflies and virus, and rogue out virus-symptomatic plants promptly. Do not save and replant slips from a patch that showed virus, since it carries over.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Clearing the weeds that host it

    Clear the weeds around the patch and keep the edges tidy. Weeds nearby can hold both whiteflies and the plant viruses they carry, so removing them takes away the launching pad.Nearby weeds host the vector and the viruses together, so clearing them and holding the margins clean reduces the reservoir feeding new introductions into the planting.

  2. Garden sanitation

    When a plant clearly has a virus, with mottled, curled leaves and stunted growth, pull it out promptly and get rid of it. A plant that has picked up a virus does not recover, so leaving it in the row just gives the whiteflies something to carry the virus away from.Rogue symptomatic plants without waiting. Infected plants do not recover, so one left standing is a source the vector can acquire from and move down the row.

  3. Water spray

    Where the whiteflies have built into heavy clusters, a strong jet of water aimed under the leaves knocks them off. Do it early in the day so the foliage dries again.A forceful spray directed at leaf undersides dislodges dense colonies where they sit and costs nothing; light numbers are worth leaving alone. Spray early enough for the foliage to dry, since a long wet period favors disease.

  4. Beneficial predators

    Put up with a few whiteflies. Helpful insects usually hold their numbers down on their own, and the harsh sprays that would wipe out the whiteflies take those helpers with them.Resident natural enemies commonly keep whitefly numbers below the level worth acting on, so tolerate light populations and stay off broad-spectrum materials, which remove the predators doing that work.

  5. Insecticidal soap

    For heavy clusters the water jet has not handled, insecticidal soap is the next step. It only acts on what it wets, so coat the undersides of the leaves directly. Keep it off drought-stressed plants and do not spray it above 90°F.Contact soap works on dense colonies on the leaf undersides, so coverage decides the result and it does nothing to what it misses. It also kills soft-bodied beneficials it wets directly, so treat the infested foliage rather than the whole patch, and avoid it on water-stressed plants or above 90°F. Note UC IPM's moderate acute rating for potassium salts of fatty acids, and wear gloves, long sleeves and eye protection when mixing and spraying, since many consumer labels do not print it.

The bottom rungs are products with label rules: timing, pollinators, and days to wait before harvest. Before you spray →

Diseases
Fusarium wilt (stem rot)
D · 01
Symptoms Lower leaves yellow and wilt, often on one side of the plant, and the vine is stunted; if you slit a stem near the base you see brown streaks inside. Badly affected plants wilt and die before making sweet potatoes. It usually comes in on infected slips or from the soil.Yellowing and wilting that starts on the lower leaves and progresses up the vine, often on one side, with stunting; a lengthwise cut of the stem near the base shows a brown, discolored streak in the water-conducting tissue. Plants may collapse before making a crop. It moves up from infected slips or through the soil. Cause A soil fungus (Fusarium oxysporum) that gets into the roots and stem and clogs the plant's plumbing. It lives in the soil for years and rides in on infected slips, and it builds up if you grow sweet potatoes in the same spot again and again.The soilborne fungus Fusarium oxysporum, which enters through the roots and stem base and plugs the vascular tissue. It survives for years in the soil and is carried on infected slips, so it builds up where sweet potatoes are grown repeatedly in the same ground. Organic treatment You cannot cure an infected plant, so pull it and throw it away (do not compost it). There is no spray fix; you prevent it with clean slips, resistant varieties, and rotating the bed.There is no cure for an infected plant; remove and destroy it. Management is preventive and variety-based: it is controlled by clean slips, resistant cultivars, and rotation, not by a spray. Prevention Plant certified, disease-free slips and choose a wilt-resistant variety if this has been a problem. Do not grow sweet potatoes in the same bed year after year, and never save slips from a patch that wilted.Start with certified, disease-free slips and grow Fusarium-resistant varieties (such as Sumor or other wilt-resistant releases) where the disease occurs. Rotate sweet potatoes out of an infected bed for several years, and do not save slips from a patch that showed wilt.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Clean planting stock

    Buy certified, disease-free slips. This fungus rides in on infected slips, so the planting material is the piece you settle before anything reaches the bed. If a patch wilted on you, do not save slips off it for next year.Certified slips close the route into ground that is still clean, since the pathogen travels on planting material as well as surviving in soil. Propagating from a patch that showed wilt carries it forward, so that stock is not worth keeping.

  2. Resistant varieties

    Where the wilt has turned up before, grow a variety bred to resist it, such as Sumor. There is no spray that fixes this one, so the variety you pick at buying time does more than anything you can do later in the season.Wilt-resistant releases such as Sumor are the durable lever on ground where the fungus is established. With no curative material available, cultivar choice and clean stock carry the program between them.

  3. Crop rotation

    Avoid growing sweet potatoes in the same bed season after season, which is how the fungus builds up. Once a bed is infected, keep the crop off it for several years before you come back.The fungus survives for years in soil and accumulates under repeated sweet potato cropping, so an infected bed wants a multi-year break rather than a single season off.

  4. Garden sanitation

    There is no way to cure a plant once it is wilting, so pull it, take it out of the garden, and bin it instead of composting it.An infected plant does not recover, so lift and destroy it rather than composting. That keeps infected tissue out of what returns to the bed, though it does not clear a soil population already there.

No spray for this one. Prevention is the control.

Root-knot nematode
D · 02
Symptoms Plants that are stunted and wilt easily even with water, and sweet potatoes that come up cracked, bumpy, and rough-skinned with little knots on them. The damage is worst in sandy soil and hot regions. You usually see it clearly only when you dig the roots.Stunted, off-color, wilt-prone vines above ground, and below ground storage roots that are cracked, bumpy, and galled, with small knots and rough, split skin that downgrade quality and storage. The southern root-knot nematode is the main species, and damage is worst in sandy soils and warm regions. Cause A microscopic soil roundworm (the southern root-knot nematode) that attacks the roots and makes them crack and knot. It lives in the soil and feeds on many crops, so it builds up when you grow the same kinds of plants in one spot over and over.The southern root-knot nematode (Meloidogyne incognita), a microscopic soil roundworm that invades the roots, causing galling and the cracked, bumpy roots that grade out. It persists in the soil and on many hosts, so it builds up where susceptible crops are grown repeatedly. Organic treatment You cannot fix roots that are already cracked and knotted. Instead, prevent it: grow a nematode-resistant variety, rotate the bed to different crops, and build up the soil with compost. In hot climates, covering moist soil with clear plastic through the summer can knock the numbers down.There is no rescue for galled, cracked roots. Management is preventive: grow nematode-resistant varieties, rotate to non-host or less-susceptible crops, and keep the soil high in organic matter. Solarizing the bed in the hot months and cover cropping can lower populations over time. Prevention Grow a nematode-resistant variety like Centennial or Covington, rotate your crops so sweet potatoes and their susceptible cousins are not in the same bed each year, and add plenty of compost. Start with certified, clean slips.Choose root-knot-resistant varieties (such as Centennial, Covington, or other resistant releases), rotate away from susceptible hosts on a multi-year cycle, and raise soil organic matter. Start with certified, clean slips so you do not introduce new populations.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Clean planting stock

    Begin with certified, clean slips. Root-knot nematodes are microscopic worms that live in the soil, and clean planting material keeps you from importing a fresh population into a bed that does not have one yet.Certified slips keep a new Meloidogyne population from arriving on planting material, which is the introduction route settled at purchase rather than in the bed.

  2. Resistant varieties

    Grow a variety with root-knot resistance, such as Centennial or Covington. In sandy soil and a warm region, where the cracking and knotting run worst, this choice does the most work.Resistant releases such as Centennial and Covington are the leading lever, and they matter most in the sandy soils and warm regions where southern root-knot nematode pressure and the resulting galled, split roots are heaviest.

  3. Crop rotation

    Rotate the bed so sweet potatoes and the other crops these worms feed on are not sitting in the same ground each year, and work cover crops into the sequence, which can bring numbers down over time. They feed on many kinds of plants, so rotation lowers the pressure rather than clearing the bed.Rotate to non-host or less susceptible crops on a multi-year cycle. The wide host range is why a short rotation returns little, and cover cropping through the off years contributes to a gradual decline rather than a reset.

  4. Soil solarization

    In a hot climate, cover the moist, cleared bed with clear plastic through the summer months. The trapped heat drives the numbers down in ground you already know is infested. It needs a genuinely hot, sunny stretch to accomplish anything.Solarizing infested ground through the hot months is the in-soil knockdown available here, run between crops rather than as routine practice. It depends on a sustained hot, sunny stretch; under cool or cloudy conditions the soil may not reach working temperatures.

No spray for this one. Prevention is the control.

Black rot
D · 03
Symptoms Dark, sunken, round spots on the sweet potatoes, firm and greenish-black to brown, and the affected part can taste bitter. It also shows as dark patches on the lower stems. It gets worse in storage and comes in on infected slips or from the soil.Round, dark, sunken lesions on the storage roots that are firm and greenish-black to dark brown, sometimes with a bitter taste in the affected tissue; on the lower stems it shows as dark cankers. It spreads in storage and in the field from infected slips and contaminated soil, and it is a major cause of cull and storage loss. Cause A fungus (Ceratocystis fimbriata) that gets into the roots and stems through cuts and bruises, lives in the soil and on old plant debris, and rides in on infected slips. It likes warm, damp conditions and keeps spreading on stored sweet potatoes.The fungus Ceratocystis fimbriata, which infects roots and stems through wounds, survives in soil and crop debris, and is spread on infected slips and by handling. Warmth and moisture favor it, and it continues to develop on stored roots. Organic treatment You cannot cure an infected sweet potato, so throw out affected ones and never store damaged roots. The fix is prevention: clean slips, gentle handling, curing right after harvest, and keeping tools and bins clean.There is no cure for infected roots; discard them and do not store blemished ones. Management is preventive: clean slips, careful handling to avoid wounds, prompt curing, and sanitation. Prevention Use certified, disease-free slips, rotate the bed, and handle the sweet potatoes gently so you do not bruise them, since the fungus enters through cuts. Cure the crop right after digging and clean up leftover roots.Start with certified, disease-free slips from clean stock, rotate out of infected beds, handle roots gently to avoid the wounds the fungus enters through, and cure the crop promptly after harvest. Discard cull and volunteer roots that carry the fungus over.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Clean planting stock

    Buy certified, disease-free slips from clean stock. This fungus travels on infected slips, so what you plant is the first place to stop it.Ceratocystis fimbriata moves on infected slips as well as persisting in soil and debris, so certified stock shuts the route that arrives with the planting material.

  2. Crop rotation

    Move the crop off a bed where black rot has shown up. The fungus survives in the soil and in old plant debris, so replanting in the same ground sets the new crop straight back down on it.The fungus carries over in soil and crop residue, so rotate off an affected bed rather than planting back into standing inoculum.

  3. Garden sanitation

    Gather up the culls and any volunteer sweet potatoes left in the bed after digging and destroy them, since they are what carries the fungus over to the next crop.Cull and volunteer roots hold the fungus over alongside soil and residue, so remove and destroy them rather than leaving or turning them under.

  4. Cure and store the harvest

    Handle the roots gently as you dig and carry them, because this fungus gets in through cuts and bruises, so a rough harvest opens the door for it. Cure the crop right after digging, pack it into clean containers, and keep blemished roots out of storage, since the rot goes on developing on sweet potatoes in the bin.Wounds are the infection court, so gentle lifting and handling are the operative control, followed by prompt curing. Warmth and moisture favor the fungus and it continues to develop on stored roots, so keep damaged or spotted ones out of the bin and use clean containers. Take the curing and storage conditions from sweet potato guidance rather than from another root or bulb crop.

No spray for this one. Prevention is the control.

Scurf and storage soft rot
D · 04
Symptoms Scurf is dark brown to black blotches on the skin of the sweet potato; it does not rot the inside, but it makes the roots look poor and dry out faster in storage. Soft rot turns bruised or too-cold roots into a soft, wet, smelly mush in the bin. Both are worst on damaged roots that were not cured or were stored wrong.Scurf shows as brown to blackish blotches on the skin surface that do not penetrate the flesh; it is a cosmetic, skin-quality problem that also increases moisture loss and shrinkage in storage. Bacterial and fungal soft rots turn wounded or chilled roots into a soft, wet, sometimes foul mush in storage. Both are worst on bruised, poorly cured, or improperly stored roots. Cause Scurf is a skin fungus that comes in on infected slips and lives in the soil. Soft rot is caused by bacteria and fungi that get into bruised roots, especially when the sweet potatoes were not cured or were stored too cold or too wet.Scurf is caused by the fungus Monilochaetes infuscans, carried on infected slips and in soil, and confined to the skin. Storage soft rots are caused by bacteria and fungi (including Rhizopus) that enter through wounds and are favored by bruising, poor curing, and cold or damp storage. Organic treatment You cannot fix scurf or soft rot. Scurfy sweet potatoes are still fine to eat once peeled, but soft, rotting ones should be thrown out. Prevent both with clean slips, gentle handling, curing, and proper warm storage.There is no rescue for scurfed or rotting roots; scurfed ones are safe to eat after peeling, but soft-rotted ones are discarded. Management is preventive: clean slips, careful handling, prompt curing, and correct warm storage. Prevention Plant certified, clean slips, rotate the bed, and be gentle with the sweet potatoes so you do not bruise them. Cure them warm and humid right after digging so the skins heal, then store them warm (not in the fridge), and never store damaged roots.Use certified, scurf-free slips, rotate out of infected beds, and handle roots gently to avoid wounds. Cure the crop warm and humid right after harvest to heal skins, then store warm (never cold or wet), and do not store bruised or diseased roots.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Clean planting stock

    Plant certified, scurf-free slips. Scurf is a skin fungus that arrives on infected slips and then stays in the soil, so clean planting material is where you head it off.Monilochaetes infuscans is carried on slips and persists in soil, so certified scurf-free stock is what keeps it out of a bed that is still clean.

  2. Crop rotation

    Rotate out of a bed where scurf has appeared, because the fungus stays behind in that soil.Rotate off infested ground. With the fungus soil-resident and confined to the skin, rotation and clean stock are the two levers that act before the crop is ever lifted.

  3. Cure and store the harvest

    Be gentle digging and carrying the roots, because bruises and cuts are where the soft rots get in. Cure them warm and humid right after digging so the skins heal over, then keep them somewhere warm rather than cold or wet; a refrigerator is too cold for sweet potatoes, and chilled roots break down into soft rot. Set bruised or spotted ones aside to eat first instead of storing them, since one rotting root spreads to what it touches. Scurf blotches sit on the skin, so peeling takes care of them.Curing warm and humid straight after harvest heals the wounds the soft rots enter through; hold the cured crop warm rather than cold afterward, since chilling and wet are what tip a bruised root into a soft breakdown. Take the temperatures from sweet potato guidance rather than from an onion or garlic crop, where cold storage is right and would injure this one. Grade out bruised, cut and spotted roots to use first rather than binning them. Scurf itself stays superficial, costing skin quality and moisture loss in storage rather than the flesh.

No spray for this one. Prevention is the control.

Verified · 5 sources View
Seasoned
Where to plant next year

Crop rotation

Move your sweet potatoes to a different spot each year and do not put them back in the same bed for about 3 to 4 years. This keeps soil diseases, nematodes, and the sweet potato weevil from building up. Planting after beans or peas is great, since those add nitrogen. Avoid beds that were just lawn, grass, or corn, where wireworms live.Rotate sweet potatoes on a 3 to 4 year cycle, keeping them out of a bed for several seasons to break the buildup of Fusarium wilt, black rot, scurf, root-knot nematode, and the sweet potato weevil. Following a legume (which adds nitrogen) or a clean, non-host crop is ideal. Avoid planting into ground recently in sod, grass, or corn, which harbors wireworms, and avoid heavily manured beds, which favor rampant vine and soft rots.

Family
Convolvulaceae
Years between
3 years
in the same bed
Avoid following
Do not grow sweet potatoes where you grew sweet potatoes in the last few years, because soil diseases and the sweet potato weevil pile up. Also avoid beds that were lawn, grass, or corn recently, where wireworms live and damage the roots, and skip beds with fresh manure or lots of nitrogen, which grow leaves instead of roots. Wait about 3 to 4 years before sweet potatoes go back in a bed.Do not plant sweet potatoes where sweet potatoes grew recently, which builds up soilborne Fusarium wilt, black rot, scurf, and the sweet potato weevil. Also avoid following ground recently in pasture, lawn, or corn, where wireworms are numerous and scar the roots, and avoid heavily manured or high-nitrogen beds, which grow vine over roots. Where root-knot nematode is present, keep sweet potatoes out of beds that grew other susceptible hosts. The standard guideline is a 3 to 4 year gap before sweet potatoes return to a bed.
Plant after
Legumes such as beans and southern peasSmall grains such as rye or wheat as a cover cropBrassicas such as cabbage and broccoliLeafy greens
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In the app · pre-launch

When plant taps you on the shoulder

The plant app sends a timely reminder at every critical moment of your sweet potato season. The wording adjusts to whichever you pick: beginner or seasoned. Here are three you'll see in Zone 9.

p
plant
3 weeks after last frost
Time to plant sweet potato slips Time to plant sweet potato slips
Plant your sweet potato slips once all frost is past and the soil has warmed to about 65°F, usually a few weeks after your last frost. Set them 3 to 4 inches deep and about 12 to 14 inches apart on ridges or mounds. Set certified slips out once all frost danger is past and the soil is above about 65°F, usually a few weeks after your last frost. Plant 3 to 4 inches deep, 12 to 14 inches apart on ridges, rows about 3 feet apart.
p
plant
10 days after planting date
Keep your new slips watered Keep new slips watered
Sweet potato slips droop for the first few days, which is normal, then perk up as they root. Keep the soil damp for the first week or two, and replace any slip that does not recover. Newly set slips often wilt for several days, then recover as they root. Keep the soil evenly moist for the first week or two, and replace any slip that fails to take.
p
plant
5 weeks after planting date
Vines are spreading now Vines are running, ease off nitrogen
As the vines spread and cover the ground, keep weeds down until they take over, and feed only a little, with a low-nitrogen fertilizer. Too much nitrogen now grows leaves instead of sweet potatoes. As the vines run and cover the bed, keep weeds down until the canopy closes and feed only lightly with a low-nitrogen fertilizer. Too much nitrogen now grows vine at the expense of roots.
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Every date, temperature, spacing, and recommendation on this page is sourced from university cooperative extension publications, peer-reviewed agricultural research, NOAA climate data, and direct extension calendars. Where claims are softer (traditional gardening wisdom not formally documented), we say so.

Research-backed Documented in cooperative extension publications or peer-reviewed research
Well-grounded A known agronomic principle, but not formally tested for this specific pair
Traditional Time-tested gardening wisdom, limited formal research support
Last reviewed
July 2, 2026
Data version
crops_data_final · v1.0 · schema 2.9
Sources cited on this page
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Verified entries
Companion-planting claims tagged inline · zone dates verified against 5+ extensions
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  • University of Minnesota Extension umn_ext
  • University of Maryland Extension umd_ext
  • Cornell Cooperative Extension cornell_ext
  • Iowa State University Extension iastate_ext
  • Michigan State University Extension msu_ext
  • NC State Extension ncsu_ext
  • Penn State Extension psu_ext
  • U. of Illinois Urbana-Champaign Extension uiuc_ext
  • UC Davis Postharvest Center ucd_postharvest
  • Texas A&M AgriLife Extension tamu_agrilife
  • Virginia Cooperative Extension 426-331 vce_426_331
  • Piedmont Master Gardeners piedmont_mg
  • UGA Vegetable Garden Calendar uga_calendar
  • Clemson Home & Garden Information Center clemson_hgic
  • UC IPM Statewide IPM Program uc_ipm
  • NOAA 1991-2020 Climate Normals noaa_normals

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Vol. 003 · Sweet Potato · plant.lifestyle