Calibrated to Pick your zone and the dates re-calibrate.

The Guide Flowers Vol. 003

Zinnia

in Zone 4, this week

Zinnias are easy, cheerful flowers you grow for blooms, not for eating. They love heat and full sun, so summer is their best season. You plant the seeds outside after your last frost, once the soil is warm, and you get your first flowers in about two months. They keep blooming until the first frost in fall. The more you cut the flowers, the more the plant makes, so cutting and removing faded blooms (called deadheading, snipping off spent flowers) keeps them going. Give plants room to breathe so the leaves stay dry and healthy. Zinnia (Zinnia elegans and related species) is a warm-season, frost-tender annual in the Asteraceae family, native to Mexico. It is grown for showy blooms, not food, across a wide size range from dwarf bedding types near 6 in to cut-flower types reaching 3 to 4 ft. Sown into warm soil after frost, it reaches first bloom in roughly 60 to 70 days and flowers continuously from summer until the first fall frost. It loves heat and full sun, so summer is its peak rather than a stress period. The defining care moves are cutting and deadheading, which drive cut-and-come-again bloom, and spacing for airflow to limit powdery mildew.

Fig. 01 · Zinnia, mature Zone 4

Mature in

60-70d

from transplant

Sunlight

Full sun

6-8 hrs daily

Water

Moderate

Spacing

9-12"

between plants

Soil pH

6-7

slightly acidic

Today · in your zone

What's happening right now

July 24 · Zone 4 · Stage 01 · Germination

Off-season for zinnia in zone 4.

The season at a glance

Planting calendar

In Zone 4, zinnia can be planted May through July. Start indoors Apr 10 - Apr 24. In bloom July through September.

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

plant

too cold

indoors

plant

too late

too cold

bloom

indoors

plant out

bloom

Keep them blooming Deadhead spent blooms through the bloom window to keep new flowers coming.

Seasoned

Stagger your sowings

Succession planting

For flowers all season, plant a new small batch of seeds every 2 to 3 weeks from after the last frost into midsummer. Fresh young plants give the best flowers late in the season. Unlike cool-season crops, zinnias love the heat, so you do not stop for summer.Sow successively every 2 to 3 weeks from after last frost through midsummer to keep a steady supply of fresh, vigorous stems; older plantings decline as the season wears on even with deadheading, so younger successions carry late-summer quality. There is no heat pause: zinnias thrive through peak summer.

Every 2 weeks · sow a short new rowUp to 12 sowings a season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

sow

bloom

keep sowing

continuous bloom

The season, mapped

Seed to garden

The easiest way is to sow zinnia seeds straight into warm garden soil (about 70 °F) after your last frost, a quarter inch deep. They do not like having their roots disturbed, so direct sowing usually works best. If your season is short, you can start them indoors 4 to 6 weeks before the last frost and move them outside afterward, handling the roots gently.Zinnias direct-sow readily into warm soil (70 °F) at 1/4 in depth and are the simplest, strongest method that way, since they resent root disturbance; transplant shock can cause double varieties to throw single blooms for a spell. To gain weeks in short seasons, start indoors 4 to 6 weeks before last frost in cells, disturb roots minimally, and transplant after frost. Pinch at four leaf sets.

01
Sow indoors →
Apr 10 - Apr 24

Start about 5 weeks before your last frost
02
Transplant out →
May 25 - Jun 15

After hardening off
03

First harvest

From Jul 27

60-70 days from transplant

Start method

Both

Soil temp

70-80°F

Hardening off

7-10 days

If you started plants indoors, harden them off first: set them outside for a little longer each day over about a week so they get used to sun and wind before you plant them out.

From seed to fruit

The growing journey

Stage 01 · Germination

Germination

Days 5-10 · current stage

The first little leaves push up through the soil in about a week.Seed leaves (cotyledons) emerge from warm soil within roughly 5 to 7 days.

Keep the soil warm and damp until the seedlings come up.Keep soil warm and evenly moist; do not let it crust or dry out during emergence.

FROM PLANT · Plant seeds outside only once the soil is warm, around 70 °F. Cold, wet soil makes the seeds rot instead of sprout, so warmth matters more than the date on the calendar.Wait for soil at about 70 °F before direct-sowing; soil temperature, not the calendar date, is the real germination trigger, and seed sown into cold, wet soil rots or damps off.

FROM PLANT · Plant the seeds about a quarter inch deep. In warm soil they usually sprout in about a week. Zinnias do not like their roots disturbed, so planting straight in the ground works best.Sow at about 1/4 in depth; zinnias germinate in roughly 5 to 7 days in warm soil and resent root disturbance, which is why direct sowing is the strongest method.

Seedling

Days 10-24

Real leaves appear and the little plant starts to settle in.First true leaves develop; the plant is small and establishing roots.

Space plants about 9 to 12 inches apart and water the soil, not the leaves.Thin or space to 9 to 12 in; water at the base to keep foliage dry.

FROM PLANT · Once seedlings have a few real leaves, thin them so plants stand about 9 to 12 inches apart. Giving them room for air to move helps prevent the white powdery mildew zinnias often get.Thin or space seedlings to 9 to 12 in once they have a few true leaves; generous spacing for airflow is a primary cultural defense against powdery mildew later.

FROM PLANT · Keep the soil damp while young plants get going, and water at the base, not on the leaves. This is one of the times zinnias most need steady moisture.Keep the soil evenly moist while seedlings establish, watering at the base; this is one of the two critical moisture windows, and overhead wetting at this stage invites early disease.

Established / vegetative

Days 22-42

The plant gets bigger and bushier with more leaves.Plant grows bushier with several true-leaf sets and begins branching.

Pinch off the top above the fourth set of leaves to make it branch out.Pinch above the fourth leaf set to force branching; maintain spacing and airflow.

FROM PLANT · When plants have about four sets of leaves, pinch off the very top. This makes the plant branch out and grow bushier, giving you more and longer flower stems.Pinch the growing tip above about the fourth set of true leaves to force basal branching; pinched plants produce more numerous, longer, sturdier stems than unpinched ones.

FROM PLANT · As plants grow, keep air moving between them and keep watering the soil, not the leaves. Full sun, space, and dry leaves are what keep that white powdery mildew away, especially in humid areas.Maintain airflow and water at the base as plants fill in; full sun, spacing, and dry foliage together keep powdery mildew and leaf spot in check, sharpest where humidity is high.

Budding

Days 42-62

Flower buds start to form at the tops of the stems.Flower buds form at stem tips; stems lengthen toward bloom.

Keep the soil evenly moist and start checking for mildew and bugs.Keep moisture even at bud point; begin scouting for mildew and pests.

FROM PLANT · Keep the soil evenly moist when the first flower buds appear. Letting plants get too dry now means shorter stems and smaller flowers.Sustain even moisture as the first buds form; drought stress at bud point shortens stems and reduces bloom size, so this is the second critical moisture window after establishment.

FROM PLANT · As plants get bushy, check for the white powdery mildew or dark leaf spots, and for Japanese beetles in early summer. Removing affected leaves and easing crowding early keeps problems from spreading.Scout for early powdery mildew and leaf spot as the canopy closes and for Japanese beetles in early to midsummer; addressing crowding and removing affected leaves early limits spread.

Flowering

Days 60-70

Flowers open, about two months after planting, and keep coming until frost.Blooms open fully and continuously; first bloom is roughly 60 to 70 days from sowing and continues to first frost.

Keep cutting flowers and removing faded ones to get more blooms.Cut and deadhead regularly to drive continuous bloom; water at the base.

FROM PLANT · Keep cutting flowers and snipping off faded ones, cutting back to the next set of leaves. This tells the plant to make more flowers instead of seeds, so you get blooms all the way to the first fall frost.Cut and deadhead continuously: removing spent and cut blooms back to the next leaf node redirects energy from seed set into new flowers, driving cut-and-come-again bloom from summer to first frost.

FROM PLANT · Cut zinnias when the flower is fully open and the stem just under it feels firm, not floppy. Zinnias do not keep opening in the vase, so picking them too early gives shorter-lived flowers.Harvest stems when blooms are fully open and the stem is firm just below the flower (the wiggle test); zinnias do not open much after cutting, so cutting too early shortens vase life.

Seed saving (optional)

Days 80-105

A few flowers left on the plant dry out and form seeds.Selected heads left on the plant dry to brown and set viable seed.

Let a few flowers dry out fully on the plant before collecting their seeds.Leave chosen heads to dry fully before collecting seed; expect hybrids not to come true.

FROM PLANT · To save seeds, leave a few flowers on the plant and let them dry out and turn brown before you pick them. Note that seeds from hybrid zinnias will not grow into the same flower next year.To save seed, let some heads stay on the plant and dry fully to brown before collecting; zinnias are open-pollinated insect-pollinated, so seed from hybrids will not come true to type.

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

Zinnias grow in most ordinary garden soil as long as water drains away and does not pool. Mixing in a little compost helps. The main thing to avoid is soggy, waterlogged ground.

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 · 6-8 hrs/day

Water

moderate

Spacing

9-12 inches

Soil

loam, sandy loam

Days to maturity

60-70 days from transplant

Soil pH

6 to 7

Container OK?

Yes · 1+ gal pot

Germination temp

70-80°F

Soil chemistry

Soil pH for zinnia

Preferred

6 to 7

Tolerated

5.5 to 7.5

Zinnias are not picky about soil pH (how acidic or alkaline the soil is). A normal garden range around 6.0 to 7.0 is fine, and you usually do not need to change anything.Zinnias are not pH-fussy and perform across roughly 6.0 to 7.0, tolerating slightly outside that. No pH adjustment is typically warranted for them specifically.

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Steady hand on the hose

Watering

When & how much

Frequency

Keep the soil damp while seeds sprout and plants get going. After that, water deeply but less often. Grown-up zinnias handle dry spells well, so you do not need to water every day.Keep soil evenly moist through germination and establishment, then water deeply but less often; established plants are notably drought-tolerant and over-frequent shallow watering invites foliar disease.

Amount

Zinnias like about one inch of water a week, counting rain. Water deeply once or twice a week instead of a little every day. Once they are established, they handle dry spells well.Aim for roughly one inch of water per week from rain plus irrigation during active growth, applied deeply and less often rather than in frequent shallow doses; established plantings tolerate less. Deep, infrequent watering encourages deeper roots and keeps foliage dry.

Method

Water the ground around the plant, not the leaves. A soaker hose or watering can at the base works best. If leaves do get wet, water in the morning so they dry by midday. Dry leaves help prevent disease.Water at the base with drip or a soaker hose and avoid overhead wetting; if you must use a sprinkler, water in the morning so foliage dries fast. Dry leaves are the single biggest lever against powdery mildew.

Signs of trouble

Too much water

If lower leaves turn yellow, the plant wilts even though the soil is wet, or the base looks mushy, you are likely overwatering or the soil drains poorly. Wet leaves also invite disease.Yellowing lower leaves, wilting despite wet soil, and root or crown rot signal overwatering or poor drainage; persistently wet foliage also raises powdery mildew and leaf-spot pressure.

Too little water

Zinnias that are too dry wilt in the afternoon heat, look dull, and make shorter stems or smaller flowers. They are thirstiest right after planting and when the first buds form.Wilting in the heat of the day that recovers by evening, dulling leaf color, and shortened stems or reduced flower size at bud point to underwatering, most critically during establishment and at first bloom.

Feeding rhythm

Feeding

Frequency

light

Type

Balanced or low-nitrogen

When to start

At planting, then sparingly

Zinnias do not need much feeding. Mix some compost into the soil before planting and that is often plenty. Too much fertilizer, especially the high-nitrogen kind, gives you lots of leaves but fewer flowers, so go light.Zinnias are light feeders; rich organic soil plus a modest dose at planting is usually enough. Excess nitrogen pushes soft leafy growth at the expense of bloom and worsens mildew susceptibility, so favor a balanced or slightly phosphorus-leaning feed over a high-nitrogen one.

N · P · K = 10-10-10

The three numbers on fertilizer (N-P-K) are nitrogen, phosphorus, and potassium. For zinnias, pick a balanced one like 10-10-10 rather than a high first-number (nitrogen) lawn feed.A balanced ratio such as 10-10-10, or a bloom-oriented lower-nitrogen blend, suits zinnias better than a high-nitrogen lawn-type feed.

Flower care

Deadheading zinnia

Flower form

single to fully double, daisy- to dahlia-form

Deadheading means snipping off flowers once they fade. Do it regularly: cut the old bloom back to the next set of leaves, and the plant will make more flowers instead of going to seed. Cutting fresh flowers for a vase does the same job. When plants are young, pinch out the top above the fourth set of leaves to make them branch out bushier with more stems.Deadhead spent blooms back to the next leaf node throughout the season to redirect energy from seed set into new flower production and sustain cut-and-come-again bloom. Cutting for the vase serves the same function, so a working cutting garden is effectively self-deadheading. Pinch young plants at about four true-leaf sets to force basal branching and longer, more numerous stems.

Who grows well together

Companion planting

Zinnias are mostly planted to help other crops. They are one of the best flowers for attracting bees and butterflies, so gardeners plant them next to or around vegetables (like tomatoes, squash, and beans) to bring in pollinators and helpful bugs that eat pests. Open, flat, single flowers feed pollinators best. There is no plant you need to keep zinnias away from. The only thing to watch is crowding: packing them tightly against bushy, disease-prone plants traps damp air and makes powdery mildew (a white coating on leaves) more likely, so give them room for air to move. Zinnia's companion role inverts the usual framing: it is the crop you place to benefit others. As one of the best annual pollinator magnets, especially for butterflies, it is interplanted between vegetable rows or as a border to pull bees, hoverflies, and predatory insects toward fruiting and cucurbit crops, and it doubles as a trap crop that can draw Japanese beetles and aphids off more delicate plants. Tall, single, wide-faced blooms with prominent disc florets serve pollinators better than dense doubles. There is no biologically antagonistic companion to avoid; the only caution is spacing. Crowding zinnias against dense, disease-prone neighbors traps humidity and raises shared powdery-mildew pressure, so site for airflow rather than avoiding any particular plant.

Other

Tomatoes

Zinnias draw bees and helpful predator insects that improve tomato pollination and pest control when planted nearby.With tomatoes, zinnia's contribution is mostly beneficial insects rather than pollination, since tomatoes self-pollinate. Zinnia's nectar draws hoverflies, lacewings, and parasitic wasps whose larvae prey on aphids and other soft-bodied pests that bother tomatoes, and the bold blooms can pull some pests onto the zinnias instead. Site them at the bed edge as an insectary strip; expect predator support and color, not a direct pollination boost. Traditional

Cucurbits (squash, melon, cucumber)

Squash, melons, and cucumbers need insects to move pollen to make fruit. Zinnias bring in the bees that do that job.This is zinnia's strongest vegetable pairing, because cucurbits depend on insect pollination, squash and melon flowers need several bee visits to set fruit properly, and zinnia is a reliable, long-blooming bee and butterfly magnet right through the cucurbit fruiting window. More pollinator traffic means better fruit set and fewer aborted or misshapen fruits. As a bonus, zinnias can also draw cucumber beetles and aphids onto themselves. Plant them in nearby rows so the pollinators they pull in spill over onto the crop. Well-grounded

Beans

Zinnias bring in bees and helpful bugs without crowding beans for food, since beans make their own nitrogen.Beans gain mostly from the beneficial insects zinnia brings in. The nectar supports parasitic wasps and predators that help manage bean beetles and aphids, and the flowers add pollinator traffic and structural diversity to the planting. Beans are largely self-pollinating, so the value here is predator recruitment and habitat rather than pollination. Keep zinnias to the edges so they do not shade lower bush beans. Traditional

Corn

A traditional pairing: zinnias planted near corn draw in pollinators and helpful insects.Corn benefits the least directly of zinnia's partners, since corn is wind-pollinated and gets nothing from added bee traffic. What zinnia offers is general garden-ecosystem support, drawing predators and parasitoids that prey on aphids and caterpillars, including corn pests like corn earworm to a degree, plus color and diversity. Treat this as a loose, habitat-level pairing rather than a targeted one. Traditional

Provenance tagged inline · see methodology for the labeling system Key

Cutting for the vase

When to cut

Cut zinnias for a vase when the flower is almost fully open. Test the stem first: hold it and give a gentle shake. If it stands up straight and stiff, it is ready to cut. If the flower flops over, wait a day or two. Cut in the morning and put the stems straight into clean water. Cut flowers usually last a week or longer indoors.Harvest for the vase when the bloom is nearly but not fully open and the stem is firm from the cut point to just below the flower head; a stem that stays rigid when gently shaken is ready, a floppy one is not. For longest vase life, cut before the small true flowers (the disc florets) emerge at the center. Cut in the cool of morning into clean water. Typical vase life is one week or more.

Bloom yield

What to expect

One cut-flower zinnia can give you dozens of flowers over the summer if you keep cutting, often a stem or more each week at its peak. The small bedding types make lots of little flowers for color rather than for cutting.A single cut-flower zinnia, pinched and cut regularly, yields dozens of stems over a season, often a stem or more per week per plant at peak; dwarf bedding types produce more, smaller blooms for color rather than cutting.

Zinnias flower the same year you plant them, usually about two months after sowing. There is no waiting year. Plant in spring and you will have flowers from summer until the first frost.Zinnias bloom the first season from seed, typically about 60 to 70 days after sowing, so there is no establishment year; a spring sowing flowers from summer to first frost.

What changes yield

Cultivar type: tall cut-flower varieties yield long stems for the vase; dwarf bedding types yield more, smaller blooms for color.Cutting and deadheading cadence: frequent cutting drives cut-and-come-again production; neglected plants set seed and slow.Pinching: pinched plants branch and yield more, sturdier stems than unpinched single-stem plants.Spacing and airflow: adequate spacing sustains healthy foliage and longer productive life by limiting powdery mildew.Season length: a longer frost-free season and successive sowings extend total stem yield into fall.

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Pick your variety

Recommended varieties

If powdery mildew (a white coating on leaves) is common where you garden, the most important choice is the variety: Profusion and Zahara types resist it and stay healthy in heat and humidity. For tall flowers to cut and put in a vase, pick double-flowered types like Benary's Giant or State Fair. For pots and small spaces, the compact Profusion and Zahara types are easiest. Flat, open, single flowers with an obvious center are the best for feeding bees and butterflies.Variety choice is the highest-leverage disease decision: the interspecific hybrid series Profusion and Zahara (Zinnia x marylandica) are bred for powdery-mildew and leaf-spot resistance and hold up in hot, humid conditions where tall Zinnia elegans types mildew. For cutting, the tall fully double elegans types (Benary's Giant, State Fair, Queen, Oklahoma) give the best stems and vase performance; for beds, borders, and containers, the compact resistant hybrids are the low-maintenance pick. Single and semi-double, wide-faced blooms with prominent centers serve pollinators best.

Benary's Giant

tall, large fully double dahlia-form, premier cut flower

State Fair Mix

tall, large blooms, vigorous

Queen Lime / Queen series

tall, muted designer tones, cut flower

Oklahoma series

tall, smaller flor-quality double blooms, strong stems

Profusion series

interspecific Zinnia x marylandica, powdery-mildew and leaf-spot resistant, compact

Zahara series

interspecific Zinnia x marylandica, disease-resistant, compact, low-maintenance

Cactus-flowered / Giant Cactus

quilled, shaggy petals

Thumbelina

dwarf bedding, container and edging

In the vase

Vase life

Zinnias are flowers for a vase, not food to store, so there is nothing to refrigerate or freeze. To make cut flowers last, trim the stem ends, pull off any leaves that would sit under the water, and use a clean vase with fresh water. Keep them out of hot sun. They usually stay nice for a week or more.Zinnia is a cut flower, not a stored edible, so the refrigerate and freeze fields do not apply. For vase life, recut stems on arrival, strip leaves below the waterline, use clean water with floral preservative, and keep blooms out of direct sun and away from ripening fruit. Expect one week or more.

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When something goes wrong

Common problems

Leaves got a white, powdery coatingWhite powdery coating on leaves (powdery mildew)

01 of 06

What happened A fungus called powdery mildew spread on the leaves. It thrives when plants are crowded, the air is humid, and leaves stay wet.Powdery mildew took hold, favored by humidity, cool nights, crowding, and wet foliage. It is the signature zinnia foliar disease. Next season Give plants more room next time so air moves between them, water the soil instead of the leaves, and try resistant types like Profusion or Zahara.Space plants generously for airflow, water at the base, site in full sun, and choose interspecific resistant series such as Profusion or Zahara where mildew pressure is high.

Plants grew tall and spindly with few flowersTall, leggy plants with few blooms

02 of 06

What happened The plants were not pinched, or got too much high-nitrogen feed, so they grew tall and leafy instead of full and flowery.Unpinched plants and too much nitrogen drive single-stem, leafy growth at the expense of branching and bloom; low light also reduces flowering. Next season Next time, pinch the tops when plants are young to make them bushy, go easy on fertilizer, and plant in full sun.Pinch above the fourth leaf set to force branching, keep nitrogen modest, and grow in full sun.

Young seedlings fell over and diedSeedlings collapsed at the soil line (damping-off)

03 of 06

What happened A fungus rotted the seedlings at the base, usually because the soil was too cold and wet when they were planted.Damping-off, a fungal collapse at the stem base, struck seedlings sown into cold, wet soil or kept too wet. Next season Wait until the soil is warm, around 70 °F, before planting, and do not keep the soil soggy.Wait for soil at about 70 °F before sowing, avoid overwatering, and ensure good drainage.

Frost killed or damaged the plantsPlants blackened by frost

04 of 06

What happened Zinnias cannot handle frost. A late spring frost or the first fall frost will damage or kill them.Zinnia is frost-tender; frost at either end of the season, planting out too early in spring or the first frost in fall, kills or damages plants. Next season Plant only after your last frost in spring, and know that the first frost in fall ends the zinnia season.Direct-sow or transplant only after all frost danger has passed, and expect plants to end with the first fall frost.

Few or no seeds sproutedSeeds failed to come up

05 of 06

What happened Cold soil is usually why zinnia seeds do not sprout well. Planted too early in cool soil, they come up poorly or rot.Cold soil is the usual cause of poor zinnia germination; seed sown before soil reaches about 70 °F germinates slowly, erratically, or rots. Next season Wait for warm soil around 70 °F, plant a quarter inch deep, and keep it damp until they sprout.Wait for warm soil (about 70 °F), sow at 1/4 in, and keep evenly moist during emergence.

Bugs chewed the flowers and leavesFlowers and leaves chewed (Japanese beetles)

06 of 06

What happened Japanese beetles, which love zinnias, chewed the flowers and leaves in early summer. Aphids and tiny spider mites can also show up.Japanese beetles, which favor zinnia as a host, skeletonize foliage and feed on blooms in early to midsummer; aphids and spider mites can also build up. Next season Pick beetles off in the early morning and drop them in soapy water; do not use beetle traps, which draw more in. Spray aphids and mites off with water or insecticidal soap.Hand-pick beetles at dawn into soapy water and avoid pheromone traps, which concentrate them; hose off or use insecticidal soap for aphids and mites.

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The usual suspects

Pests & diseases

Pests

Aphids

P · 01

Japanese beetles

P · 02

Spider mites

P · 03

Diseases

Powdery mildew

D · 01

Alternaria and bacterial leaf spot

D · 02

Seasoned

Where to plant next year

Crop rotation

Rotating zinnias is not as important as it is for vegetables, but it still helps. Plant them in a different spot each year if you can, and clean up old, diseased leaves at the end of the season so problems do not carry over.Rotation matters less for a fast-growing ornamental annual than for heavy-feeding vegetables, but moving zinnias to a fresh bed each year and clearing infected debris at season end limits carryover of powdery mildew and leaf-spot inoculum.

Family

Asteraceae

Years between

1 years

in the same bed

Avoid following

Zinnias are in the daisy family (Asteraceae). If they had a lot of disease, do not plant them, or other daisy-family flowers, in the same spot the very next season. Give the bed a year with a different kind of plant.As an aster-family (Asteraceae) annual, avoid following zinnia immediately with other susceptible asters where soilborne or foliar disease has built up; rotate the bed to an unrelated family for a season if powdery mildew or leaf spot was heavy.

Plant after

legumesleafy 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 zinnia season. The wording adjusts to whichever you pick: beginner or seasoned. Here are three you'll see in Zone 4.

plant

Last frost arrives

Time to plant zinnias

Your last frost has passed, so you can plant zinnia seeds outside once the soil feels warm, about a quarter inch deep.

plant

Established arrives

Pinch your zinnias now

Your zinnias should have about four sets of leaves now. Pinch off the tops so they grow bushier with more flowers.

plant

Flowering arrives

Time to cut and deadhead

Your first flowers are opening. Keep cutting them and snipping off faded ones to get more blooms all season.

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Seasoned

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If you've grown this crop and you see a date, a temperature, a companion claim, or a recommendation that doesn't match your experience, tell us. Real growers' corrections make this guide better for the next person.

How we built this guide

Methodology & sources

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

June 15, 2026

Data version

crops_data_final · v1.0 · schema 2.9

Sources cited on this page

16 publications

Verified entries

Companion-planting claims tagged inline · zone dates verified against 5+ extensions

See all sources cited on this page

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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