Lemongrass in Zone 9 -- plant

Subzone	Last spring	First fall	Growing days	Winter min	Fruits reliably
9a	Mar 8	Nov 24	~261	20-25°F	Yes · two seasons
9b	Feb 28	Nov 30	~275	25-30°F	Yes · two seasons

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

Give lemongrass rich, moist soil that has been improved with plenty of compost. It is a hungry, thirsty grass, so the better the soil, the bigger the clump. Make sure the spot still drains, because soil that stays soggy can rot the 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 · 6-8 hrs/day

Water

High

Spacing

3 feet

Soil

loam, sandy loam

Days to maturity

75-120 days from transplant

Soil pH

6 to 7.5

Container OK?

Yes · 3+ gal pot

Germination temp

70-85°F

In a pot

Yes, 3 gallons and up

Lemongrass grows very well in a big pot, which is the easiest way to grow it in cold areas since you can bring it inside for winter. Use a large pot (5 gallons is great) with good drainage and rich mix. Water and feed pots more often than ground plants. Divide the clump in spring when it fills the pot.Lemongrass is an excellent container plant, and in cold regions a pot is the practical way to grow it, because it can be moved indoors before frost. Use a large pot (at least 3 gallons, ideally 5 or more) to support the vigorous clump, with ample drainage holes and a rich, free-draining mix. The main tradeoffs of container culture are water and feeding: pots dry and leach faster than ground soil, so both must be more frequent. A potted clump outgrows its container within a season or two and benefits from spring division.

Pot size: 3 gallons and up; 5 gallons is comfortable
Mature size: 3 to 6 feet tall, 2 to 3 feet wide
Drainage: Drainage holes are a must. Skip the gravel layer. After watering, empty the saucer under the pot. Lemongrass drinks a lot but its roots rot if left standing in water.Drainage holes are a must. Skip the gravel layer. Empty the saucer after each watering; despite its thirst, lemongrass rots if its roots sit in standing water.
Watering: Pots dry out fast, so check container lemongrass daily in summer and water until it drains out the bottom.Container lemongrass dries out fast and needs frequent, generous watering, often daily in summer heat; water until it drains from the bottom and never let the pot stand in water.
Depth and shape: At least 10 inches deep.
Self-watering pot: Yes. Self-watering containers suit this high-water-demand grass well, keeping the reservoir topped up during hot weather. Ensure the mix wicks moisture without becoming waterlogged, and let the reservoir draw down periodically to keep the roots healthy.
Mix: A rich, moisture-retentive but free-draining potting mix, ideally amended with compost for fertility. Blend in compost for fertility; this heavy feeder benefits from an organically rich mix that still drains freely
Feeding: Feed container plants more often than in-ground clumps, since frequent watering leaches nutrients; a half-strength soluble feed every week through active growth suits them.

One to try

West Indian lemongrass (Cymbopogon citratus)The common culinary lemongrass, of Malaysian origin, grown for its thick, tender edible stalks; this is the type sold as grocery-store lemongrass and the one to grow for cooking.

Winter

To keep lemongrass over winter, grow it in a pot. Before the first frost, cut it back to a few inches and move the pot to your sunniest indoor window. Water it less and do not feed it through winter. When frost is past in spring, put it back outside. This lets you keep the same plant year after year.In any zone that frosts, a container is the standard way to carry lemongrass over winter. Before the first fall frost, cut the plant back hard (to roughly 4 to 6 inches, which also sheds pests) and bring the pot to the brightest indoor spot available; a large clump can be divided down to a smaller pot first. Kept in bright light, watered less, and unfed through winter, it holds until spring, when it can go back outside after frost. This is also how gardeners in cold zones keep a favorite plant going year to year rather than buying new each spring.

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 lemongrass

Preferred

6 to 7.5

Tolerated

5.5 to 8

Lemongrass is easygoing about soil pH. Aim for roughly 6.0 to 7.5, which is ordinary garden soil, and you will not need to make any special adjustment.Lemongrass is not fussy about pH and tolerates a wide range of soils. A preferred range of 6.0 to 7.5 keeps the full spectrum of nutrients available to this fast-growing, nutrient-hungry grass, and it will grow acceptably in mildly acidic through mildly alkaline ground. No specific pH figure is published in the Tier-1 extension guides consulted, so this range is modeled from the plant's documented tolerance of varied soils and from general practice for culinary grasses.

Verified · 1 source View

Steady hand on the hose

Watering

When & how much

Frequency

Water often. In the ground, water deeply a few times a week in hot weather; in a pot, check daily and do not let it dry out.Frequently through the warm season; in-ground clumps deeply 2-3 times per week in heat, containers often daily

Amount

Keep the soil consistently moist, never bone dry. Lemongrass drinks a lot.Keep the root zone consistently moist; this is a high-water-demand grass, so err toward generous, deep watering while ensuring drainage

Method

Water at the base of the plant, not over the leaves, to help prevent leaf diseases. In a pot, water until it runs out the bottom, then empty the saucer.Water at the base by hand or flood irrigation rather than overhead sprinklers; keeping the foliage dry limits rust and leaf blight, and base watering suits this thirsty grass. In containers, water until it drains from the bottom and empty the saucer.

Signs of trouble

Too much water

Yellow, wilting leaves and a soft, dark base even though the soil is wet mean the roots are sitting in water. Improve the drainage.Yellowing and wilting despite wet soil, soft dark stalk bases, and a soured, waterlogged root zone signal root rot from poor drainage rather than too little water.

Too little water

Browning, curling leaf tips and slow growth mean it is thirsty. Lemongrass wilts and browns quickly when it runs short of water.Leaf tips and margins browning and curling, slowed clump expansion, and thin, slow-forming stalks indicate the plant is not getting enough water, especially during hot, dry spells.

Feeding rhythm

Feeding

Frequency

every 1-2 weeks

Type

nitrogen-forward soluble

When to start

Weekly to every other week through the active summer growing season; ease off as fall approaches

Lemongrass is a hungry grass and grows fastest when fed often. Use a liquid fertilizer at about half strength every week or two through the summer. If it is in a pot, feed a bit more often, since watering washes nutrients out. Stop feeding as fall nears.Like other grasses, lemongrass is a heavy nitrogen feeder, and steady feeding drives the vigorous leaf and stalk growth that makes a productive clump. Utah State Extension recommends feeding weekly with a half-strength solution of a balanced soluble fertilizer from June through September; a nitrogen-forward all-purpose liquid every one to two weeks works similarly. Container plants need more frequent feeding than in-ground clumps because nutrients leach with each watering. Taper feeding as fall approaches so growth is not pushed into cold weather.

High nitrogen

Use a general-purpose feed higher in the first number (nitrogen)Nitrogen-forward; a balanced soluble at half strength or a higher-first-number all-purpose liquid keeps this fast-growing grass in vigorous leaf

Try balanced soluble fertilizer at half strength (as recommended for lemongrass), or a nitrogen-forward all-purpose liquid

Who grows well together

Companion planting

Lemongrass grows happily next to other sun-and-water lovers like tomatoes and peppers, and its lemony scent is a traditional way to discourage some insects. Keep it away from dry-soil herbs like rosemary and sage, which want the opposite conditions. Remember that lemongrass becomes a big clump, so give it plenty of space. Lemongrass has little formal companion-planting research behind it, but two practical points hold up. First, its essential oils (rich in citral) are documented insect repellents, which is the basis for the tradition of planting it near warm-season vegetables such as tomatoes and peppers; treat the pest-deterrent benefit as traditional rather than proven at garden scale. Second, its cultural needs are the deciding factor in placement: it demands rich soil, heavy feeding, full sun, and abundant water, so it pairs naturally with other heat-loving, well-watered crops and conflicts with lean, dry-soil Mediterranean herbs. Give a mature clump ample room, since it reaches 3 to 6 feet.

Other

Tomatoes

Lemongrass and tomatoes both want heat, sun, and regular water, so they make easy neighbors. Lemongrass's strong lemony scent is a traditional way to help keep some insects away. Just give the grass its own space, because it grows into a big clump.Lemongrass shares tomatoes' love of heat, full sun, and steady water, and its strong citrus oils are a traditional insect deterrent, so gardeners often tuck a clump at the corner of a warm-season bed. Give it room, since a mature clump is large. Traditional

Peppers

Peppers love the same heat and sun as lemongrass, so they grow well side by side. The grass's lemony scent may help keep some bugs off. Give the clump room to spread out.Peppers want the same heat, sun, and moisture as lemongrass and mature on a similar warm-season schedule, so they share a bed comfortably. The grass's aromatic oils are a traditional pest deterrent for the planting. Traditional

Keep apart from

Shade-loving, moisture-shy herbs (rosemary, sage, thyme) Herbs like rosemary, sage, and thyme want dry, lean soil, which is the opposite of what thirsty lemongrass needs. If you plant them together, one will always be unhappy. Give the dry-loving herbs their own spot and let lemongrass have the rich, well-watered ground it likes.Mediterranean herbs want lean, dry, sharply drained soil, while lemongrass wants rich ground and constant moisture, so the two pull a shared bed in opposite directions. Keep the drought-tolerant herbs in their own drier spot. Well-grounded

Provenance tagged inline · see methodology for the labeling system Key

Harvest signals

When to pick

You can start harvesting once a stalk is about half an inch thick at the bottom, roughly a few months after planting. Pick a stalk from the outside of the clump: bend it to the side and twist and pull it off at the base, or cut it right at ground level. Cut off the grassy top and peel away the tough outer layers to get to the tender white part for cooking. You can snip leaves anytime to dry for tea.Begin harvesting once individual stalks have swelled to about half an inch thick at the base, which in a warm season is usually 75 to 120 days after planting a division or rooted start. Harvest a whole stalk rather than picking leaves: grasp an outer stalk, push it to the side, and twist and pull it free at the base, or cut it at ground level with a knife. Take the outermost stalks first and leave the clump intact to keep producing. Trim off the leafy top and peel away the tough outer layers to reach the tender inner base used in cooking; the fragrant leaves can be cut anytime for tea.

Yield

What to expect

One healthy clump can give you dozens of stalks by late summer, plus lots of leaves for tea. In warm, frost-free areas an established plant produces even more, year after year. In a short, cool season, expect a more modest first-year harvest.A single well-grown clump in full sun with rich soil and steady water can, by late summer, yield dozens of harvestable stalks and a steady supply through the season, plus abundant leaves for tea. In a frost-free climate an established perennial clump becomes a large, ongoing source. In one cool-region season a first-year plant yields more modestly, a handful to a couple dozen stalks depending on how early it was set out and how hot the summer ran.

Lemongrass is slow at first and only takes off when it gets hot, so a first-year plant does best if you start it early indoors and then feed and water it well all summer. The earlier and warmer the start, the bigger the first-year clump.Lemongrass starts slowly and only bulks up once real summer heat arrives, so the first-season harvest depends heavily on getting an early, well-rooted start into warm soil and feeding and watering it hard. In cold zones the biggest first-year lever is a head start indoors; a plant set out small into a short season stays small.

What changes yield

Heat and sun: a warm, full-sun site is the single biggest driver of clump size; cool or shaded plants make few, thin stalksWater: this high-demand grass needs deep, frequent watering to bulk up; drought thins the stalksNitrogen feeding: regular nitrogen-forward feeding drives the vegetative growth that produces harvestable stalksSeason length: frost-free zones grow a large perennial clump harvested year round, while short-season zones get one modest annual harvestHead start: in cold zones, an early well-rooted start set into warm soil greatly increases first-year yield

Verified · 2 sources View

Pick your variety

Recommended varieties

For cooking, choose West Indian lemongrass (Cymbopogon citratus), the kind sold in grocery stores with the thick, tender stalks. There is also East Indian lemongrass (C. flexuosus), which is edible too and used for oil. Watch out for citronella grass, a lookalike relative grown to make citronella oil and to repel bugs, not for eating. If you want to cook with it, make sure you are getting C. citratus.For cooking, grow West Indian lemongrass (Cymbopogon citratus), the species with the plump, tender stalk bases used in kitchens and the one usually sold fresh in stores. East Indian lemongrass (C. flexuosus) is also edible and is the main oil-crop species, with more slender stalks. The genus Cymbopogon holds dozens of species, and it is worth knowing that citronella grass (C. nardus and C. winterianus), the source of citronella oil, is a close relative that looks similar but is grown for repellent oil and ornament, not for eating. When buying a plant or a rooting stalk for the kitchen, confirm it is C. citratus.

West Indian lemongrass (Cymbopogon citratus)

The common culinary lemongrass, of Malaysian origin, grown for its thick, tender edible stalks; this is the type sold as grocery-store lemongrass and the one to grow for cooking.

East Indian lemongrass (Cymbopogon flexuosus)

Also called Cochin or Malabar grass. Native to India, Sri Lanka, Burma, and Thailand; also culinary and a major source of lemongrass essential oil, with somewhat more slender stalks.

Citronella grass (Cymbopogon nardus / C. winterianus)

A related but non-culinary species grown for citronella oil and as an ornamental insect-repellent plant; do not confuse it with edible lemongrass for cooking.

Off the vine

Storing your harvest

Room temp

Fresh stalks last a few days to a week on the counter. For longer storage, use the fridge or freezer.Whole fresh stalks keep for several days to about a week at cool room temperature. For anything longer, refrigerate or freeze. The tough stalks are far more durable than tender leafy herbs.

Fridge

Lemongrass keeps well in the fridge, about 2 to 3 weeks, wrapped or in a bag. Cold does not hurt it the way it does basil.Wrapped loosely or sealed in a bag, fresh stalks keep 2 to 3 weeks in the refrigerator. Unlike basil, lemongrass has no chilling-injury problem and refrigerates well.

Freezer

Lemongrass freezes very well. Freeze whole stalks or chop the tender part and freeze it in bags. It keeps its flavor for months. Dry the leaves for tea.Lemongrass freezes excellently and is the best way to keep a large harvest. Freeze whole trimmed stalks, or slice or mince the tender bases and freeze in bags or portioned in ice cube trays; frozen stalks keep their flavor for many months. Leaves can be dried for tea.

Verified · 1 source View

When something goes wrong

Common problems

Plant browned or killed by coldCold or frost damage

01 of 04

What happened Lemongrass cannot take cold. It gets damaged as temperatures head toward 40 °F, and frost kills the leaves. A hard freeze can kill the whole plant if it is left outside. The usual mistakes are planting it out too early in spring or forgetting it outdoors when fall frost comes.Lemongrass is fully frost-tender. Foliage is damaged as temperatures fall toward 40 °F, and frost kills the top growth outright; a hard freeze can kill an unprotected in-ground clump entirely. The common mistake is planting out too early in spring or leaving the plant outdoors into fall frost. There is no recovery of frosted top growth, though a lifted or well-mulched crown may resprout in borderline zones. Next season Wait until frost is fully past and the soil is warm to plant it out. In fall, harvest before frost and bring a potted piece indoors for winter. In cold areas, plan to grow it in a pot you can move inside.Plant out only after all frost danger has passed and the soil has warmed. In fall, harvest before first frost and lift and pot the clump (or a division) to overwinter indoors in bright light. In zones colder than about 8b, treat it as an annual or a keep-it-in-a-pot plant.

Plant is spindly with only a few stalksFew, thin stalks (too little sun or heat)

02 of 04

What happened Lemongrass in too much shade, a cool summer, or without enough water and feeding makes just a few thin stalks and barely grows. It needs full sun, heat, lots of water, and regular feeding to bulk up.Lemongrass grown in shade, in a cool-summer climate, or without enough water and food produces only a few slender stalks and expands slowly; in deep shade it can decline and die. As a heat-loving grass it needs full sun, warmth, generous water, and regular nitrogen to build the dense clump that yields thick stalks. Next season Give it the sunniest, hottest spot you have, water it a lot, and feed it through summer. In a cool-summer area, grow it in a pot in a hot spot and start it early indoors.Move it to the hottest, sunniest spot available, water deeply and often, and feed a nitrogen-forward fertilizer through summer. In cool-summer regions, grow it in a pot in a hot microclimate (against a south wall, on paving) and give it a head start indoors.

Plant yellows and rots in soggy soilYellowing and rot from waterlogged soil

03 of 04

What happened Lemongrass loves water but not soggy roots. If the soil or pot stays waterlogged, the plant yellows, wilts, and rots at the base even though it is wet. The problem is drainage.Despite its high water demand, lemongrass rots when its roots sit in waterlogged soil or a poorly draining pot. Symptoms are yellowing, wilting, and soft dark stalk bases even though the soil is wet. Drainage, not watering volume, is the failure here. Next season Grow it in soil or a pot that drains well. Water a lot, but make sure the extra water runs out and the pot never sits in a full saucer.Plant in well-drained, organically rich soil; in containers use a free-draining mix with ample holes and empty the saucer after watering. Water generously but let the excess drain freely rather than pooling.

Orange-brown spots drying the leavesRust (Puccinia nakanishikii)

04 of 04

What happened Rust is a fungus that puts yellow flecks and orange-brown spots on the leaves and dries them out. It shows up in warm, humid weather, especially on crowded plants.Lemongrass rust, caused by Puccinia nakanishikii, produces yellow flecks that redden into streaks and orange-brown pustules on the leaf undersides, drying the foliage in severe cases. It is the most notable disease of lemongrass in warm, humid regions and is worsened by crowding and prolonged leaf wetness. Next season Give plants room, divide crowded clumps, water at the base, and cut off spotted leaves. A copper spray can help if rust keeps coming back. Full sun and healthy, uncrowded plants resist it best.Improve airflow by spacing and dividing clumps, water at the base to keep foliage dry, and remove infected leaves promptly. Copper-based fungicides can be used preventively under heavy pressure. Full sun and vigorous, uncrowded plants resist rust best.

Verified · 7 sources View

The usual suspects

Pests & diseases

Pests

Spider mites (indoor and hot, dry conditions)

P · 01

Symptoms Tiny specks and a faded, dusty look on the leaves, sometimes with fine webbing. This shows up mostly on plants kept indoors over winter.Fine stippling or a dusty, faded look on the leaf blades, sometimes with fine webbing, most often on plants overwintered indoors or grown hot, dry and dusty. As feeding builds, the speckling runs together and the whole blade looks washed out. Cause Spider mites are tiny pests that love warm, dry indoor air. They tend to appear on lemongrass that is overwintering inside.Spider mites (Tetranychidae) thrive in the warm, dry, low-airflow conditions of a heated indoor room, which is exactly where potted lemongrass spends the winter. They are far less of a problem on well-watered outdoor clumps. Organic treatment Spray the leaves hard with water to knock the mites off, then repeat every couple of days for a week. If they hang on, use insecticidal soap or horticultural oil and coat both sides of every blade, since these only work where they land.Rinse the foliage with a strong jet of water, repeating over about a week, and treat what survives with insecticidal soap or horticultural oil, covering both faces of the blades. Neither product has any residual, so coverage is what decides the result. Do not spray in heat over 90°F, and do not spray a plant that is already short of water; burn risk climbs on both. Prevention Water lemongrass steadily instead of letting it dry out, and rinse dust off the leaves. Mites are mainly an indoor winter problem on this plant, so check the blades when the pot comes inside and again every few weeks through the winter.Keep the plant watered rather than letting it swing dry, and keep dust off the foliage, since UC IPM names water stress and dusty conditions as what favors mites. The risk window is the indoor winter, so start looking the blades over when the pot comes inside and keep checking through the heating season, when this pest is most likely to appear.

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.

Even watering

Do not let lemongrass go dry. Mites build up fastest on a plant that has been left short of water, and they like hot, dusty air, so keeping this thirsty grass watered takes away the condition they do best in. A pot standing beside a driveway collects the dust as well, so rinse it off when you water.UC IPM puts the two drivers side by side: mites prefer hot, dusty conditions, and plants under water stress are highly susceptible. That is convenient here, because lemongrass is a heavy water user anyway, so the irrigation that builds a thick stalk is the same irrigation that holds mite pressure down. The stretch to watch is winter indoors, where a heated room supplies the hot, dry, dusty air and a pot in low light is easy to leave dry.
Water spray

Wash the mites off with a strong jet of water. This is Utah State's own advice for lemongrass, it costs nothing, and it is the first thing to try. Take an indoor pot to the shower or the sink and run the water along both sides of every blade.Both anchors lead with water: USU says to spray the plant with a forceful jet to knock the mites off, and UC IPM says regular forceful spraying often reduces numbers adequately on its own. So treat it as a repeated habit over a week or so, not one pass. Long blades make thorough coverage easier than on a bushy crop, since you can run the stream up each face of the blade. Outdoors, do it in the morning: rust needs wet leaves to infect, so a clump left soaked into the evening is doing the rust a favor.
Beneficial predators

Outdoors, other small hunters usually keep mites in check for you at no cost. The quickest way to lose that help is a broad insecticide, which kills the helpers along with the mites, so leave an outdoor clump to sort itself out unless it is really suffering.UC IPM records that spider mites have many natural enemies that often limit their numbers in gardens, especially when they are undisturbed by pesticide sprays. Set that beside USU's scoping of this pest as mostly an indoor plant problem and the shape of the risk is clear enough: the outdoor clump has that pressure working on it and a windowsill pot does not. It argues for restraint outdoors, and against expecting the same free help from the plant in the house.
Insecticidal soap

When rinsing alone stops holding the mites down, move up to insecticidal soap. Anything the spray misses survives, so coat both faces of the blades instead of misting over the top of the clump. Pick a mild day under 90°F, and water a dry plant well before you spray, because soap scorches foliage that is hot or thirsty.USU names insecticidal soap as its treatment for this pest, and UC IPM offers soap or oil once water alone is not enough. There is no residual, so coverage and repetition decide the outcome, and a narrow upright grass sheds a light spray easily, which is the practical reason a first pass under-performs. The two label limits both raise burn risk: skip a day hotter than 90°F, and skip a plant that is already short of water.
Horticultural oil

A light horticultural oil smothers mites just as the soap does, and it asks the same thoroughness: every blade, top and bottom. Settle on one product rather than alternating them, and keep it off a plant that is hot or short of water.UC IPM's phrasing is soap or oil, so this is an alternative rather than a step up. Oil clings a little longer, which suits an indoor plant that cannot easily be carried out for repeated rinsing. The same restrictions apply, nothing above 90°F or on stressed foliage, and leave at least 30 days between an oil spray and any sulfur while the plant is in leaf, the interval this entry's own UC IPM note gives; check the oil label, since some specify longer.

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

Diseases

Lemongrass rust

D · 01

Symptoms Rust begins as tiny yellow spots that stretch into brown stripes running along the leaf, and on the underside those stripes break open into dusty, cinnamon-brown spots. Badly hit leaves brown and die early. It rarely kills the plant, and CTAHR says leaves from a rusted plant are still safe to dry for tea or to use in cooking.Rust starts as tiny, light yellow spots that lengthen into brown, stripe-like lesions running with the veins on both sides of the blade. On the lower surface those lesions erupt into dark, cinnamon-brown pustules. Where lesions run together they form large leaf spots or blighted areas and the leaves die early. Defoliation can be heavy, but CTAHR records that the disease is normally not fatal to the plant. Cause A fungus called Puccinia nakanishikii. It needs the leaves to be wet to get in, and warm, humid, rainy weather is what suits it. Spores blow in on the wind or splash up in rain and watering, and they can live on fallen leaves.Rust caused by the fungus Puccinia nakanishikii, documented for growers by the University of Hawaii's CTAHR in PD-57. High rainfall, high humidity and warm air favor it. Spores travel on wind, splashing rain and irrigation water, and infect leaves that are wet or moist during periods of very high humidity; they may also survive on infected or fallen leaves. PD-57 reports the disease from Hawaii, California and New Zealand, and notes it may be established in other places where lemongrass is grown. Organic treatment Trim off the badly rusted leaves and throw them out, and do not spread them under the plant as mulch, because the spores can live on them. Put the water on the ground rather than over the leaves, and thin a crowded clump so air moves through it. There is no spray worth recommending here: only one product is registered for this disease in Hawaii, and CTAHR says even that one has not been tested there.Culture is the control here. Cut back or thin the diseased leaves so clean regrowth can come, destroy what you cut instead of laying it around the clump as mulch, water at the base rather than overhead, and open the planting up so leaves dry faster. There is no spray to recommend: PD-57 records exactly one fungicide product registered for lemongrass rust in Hawaii, a neem-oil product, and says plainly that no published research there has evaluated it. A Darluca mycoparasite has been found in rust pustules in coastal California, but PD-57 does not know whether it controls anything, so it is not something to buy or count on. Prevention Buy a clean plant, give the clump room in an open, airy spot, keep weeds down around its base, and water at the soil so the leaves dry quickly. Clear away any rusted leaves you cut instead of leaving them lying under the plant.Start clean: PD-57's first line of defense is not to buy or pass on rusted plants, which matters for a crop that moves around as divisions and rooted stalks. Then site and space for dry leaves, a relatively dry or well ventilated spot, clumps not planted close together, and weeds kept down so humidity does not build inside the canopy. Water at the base, and keep diseased trimmings away from the plant, since spores can survive on fallen leaves.

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.

Clean planting stock

The cheapest control is not bringing the disease home in the first place. CTAHR's advice is not to buy or pass on rusted plants, so turn the leaves over before you accept a division or a potted plant, and refuse one carrying dusty brown spots rather than trimming them off and hoping.PD-57 lists 'do not purchase or distribute rusted plants' among its management practices, and it carries more weight here than it would on a seed crop: lemongrass travels as divisions, potted plants and rooted grocery stalks, which move living leaf tissue and any pustules on it. Inspect both faces of the blades on anything arriving, and remember the same rule applies when you hand a division to a neighbor.
Airflow and spacing

Rust needs the leaves to stay wet, so give the clump an open spot with moving air, leave room around it, and keep weeds down at its base. CTAHR asks for all three: a relatively dry or well ventilated site, clumps not packed together, and weeds controlled, because weeds crowding the base hold humidity in among the leaves.PD-57 names leaf wetness as the infection requirement: spores land on wet or moist leaves and infect during periods of very high humidity. Three of its eight practices act on that single variable, siting in a relatively dry or well ventilated area, avoiding large numbers of clumps planted close to one another, and keeping weeds under control to lower relative humidity inside the canopy. A mature clump gets large, so the spacing decision is made once at planting and is awkward to revisit later.
Water at the base

Put the water on the ground, not over the leaves. CTAHR's instruction is to keep overhead watering to a minimum, because the spores need wet leaves to get in and a sprinkler both wets them and splashes spores around.PD-57 names wind, splashing rain and irrigation water as how spores move, and wet or moist leaves under very high humidity as what infection needs, so overhead irrigation supplies the transport and the condition at once. Basal or flood watering suits this crop anyway. Worth knowing the limit: it governs only the water you control, and wind-carried spores and rainfall sit outside it, which is why the siting decision above does more in a wet summer.
Garden sanitation

Cut out the badly rusted leaves and take them away from the plant. CTAHR says to prune, cut back or thin diseased plants so clean new growth can come, to destroy what you remove, and specifically not to lay it around the plant as mulch, because the spores can survive on fallen leaves.PD-57 pairs the cut-back with a warning that is easy to skim past: spores may survive on infected or fallen lemongrass leaves, so diseased trimmings used as mulch put the inoculum straight back under the clump. Periodic cutting back also lets disease-free regrowth come, which fits a crop harvested by cutting whole stalks anyway. Expect it to lower the load rather than clear it, since wind moves spores between plants regardless of how clean yours is.

No spray for this one. Prevention is the control.

Leaf blight

D · 02

Symptoms Reddish brown spots on the tips and edges of the leaves, and leaves that dry out sooner than they should. If the marks instead run down the middle of the blade and rub off dusty and brown from the underside, that is rust, not this.Reddish brown spots appear at the leaf tips and along the margins, and affected leaves dry out early. The location is what separates this from rust, whose lesions run with the veins down the blade and break open into cinnamon-brown pustules on the underside. Extension guidance goes no further than that, so a leaf browning in some other pattern is worth a second look rather than an assumption. Cause Nobody has pinned down what causes it. Utah State lists leaf blight on lemongrass without naming the fungus behind it, and no other extension guide consulted names one either.Utah State lists leaf blight among the diseases of lemongrass but names no organism, and no other extension source consulted identifies one either, so there is no published cause or weather driver to give for it. Treat an unfamiliar browning as unidentified until you have looked at where on the leaf it sits. Organic treatment Pick off the blighted leaves. That is Utah State's own advice and it is the whole treatment. Its other option, a registered fungicide, only applies once the disease has been positively identified, and nobody has identified what causes this one.Hand removal is the response. Utah State offers two options, taking the blighted leaves off by hand or spraying a registered fungicide, and it makes the spray conditional on the disease being positively identified. With no source naming the organism, that condition is not one a home grower can meet, so removal is where this stops. Cut affected stalks at the base as you would for harvest and take the leaves out of the bed. Prevention There is no specific prevention published for this one. Utah State's guidance is that lemongrass stays generally free of pests and diseases when it is grown correctly, so feed and water the clump well and look the leaves over whenever you cut a stalk.No source consulted publishes conditions that favor this blight or a practice that prevents it, so there is no specific prevention step to give. What is published is broader: USU's line is that lemongrass is generally free of pests and diseases when it is grown correctly, which puts the weight on ordinary good culture, rich and well-drained soil, steady water, and looking the clump over each time you cut stalks.

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.

Garden sanitation

Pick the blighted leaves off by hand. That is Utah State's own instruction for this one, and with the browning starting at the leaf tips and edges it is easy to see which leaves to take. Cut a badly affected stalk out at the base and carry it away from the bed rather than dropping it there.USU gives two options for leaf blight, hand removal of blighted leaves or a registered fungicide, and it conditions the spray on the disease being positively identified. No source consulted names the organism behind it, so that condition is not one a home grower can meet, which leaves hand removal as the whole practical response. Taking the tissue as it browns also keeps your own eye trained on the difference from rust: rust runs down the blade with the veins and erupts into cinnamon-brown pustules underneath, while this stays at the tips and margins.

No spray for this one. Prevention is the control.

Root rot (overwatering in poor drainage)

D · 03

Symptoms The plant yellows, wilts, and rots at the base even though the soil is wet. The roots turn soft and dark. This comes from soil that stays soggy.Neither cited guide describes symptoms, so what follows is the general pattern of a root rot rather than anything published for lemongrass: yellowing, wilting and collapse of stalks despite wet soil, with soft, dark, decayed roots and stalk bases. It shows up when a thirsty plant is grown in soil that stays waterlogged, especially in a container that does not drain. Cause Lemongrass loves water but hates sitting in it. If the soil or pot does not drain, the roots rot.Lemongrass is a heavy drinker that still rots in ground which stays saturated, and the two are not in conflict: what does the damage is soil that never drains, not the amount you pour on. Illinois Extension frames it as keeping the soil moist without overwatering, and UC Master Gardeners of Santa Clara County as watering into well-drained soil. No source names an organism for lemongrass; the general cause is the soilborne fungi and water molds that need saturated pore space to move and infect, and a pot whose outlet is blocked or standing in water is where they usually get it. Organic treatment Fix the drainage, because there is no spray for this. Repot a container plant into fresh mix in a pot with plenty of holes, never let the pot stand in water, and keep watering well once the extra water can run out.There is nothing to spray for this. The response is to fix the drainage: lift a pot out of its standing saucer, repot into a mix that drains freely and a pot with ample holes, or move a bed planting to ground that sheds water. Keep watering generously once the water can get away, since the crop's need for water is not what caused the problem. Prevention Grow lemongrass in soil or a pot that drains well. Water it a lot, but make sure the extra water can run out and the pot never sits in a full saucer.Plant in well-drained, organically rich soil; in containers use a free-draining mix and pots with ample holes, and empty the saucer after each watering. Water deeply and often, but let the excess escape.

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.

Improve drainage

Give lemongrass ground or a pot that actually drains. Illinois Extension puts it plainly: water as needed to keep the soil moist, but do not overwater, because that leads to root rot, and in a pot use one with plenty of drainage holes and a proper potting mix. The rule to hold on to is water a lot and drain fast, not water less.Both cited guides carry the same two-part instruction from different directions, Illinois to keep the soil moist without overwatering, UC Master Gardeners of Santa Clara County to water into well-drained soil, which is why drainage rather than volume is the variable to act on for a grass that drinks this heavily. The container is the usual failure, since drainage holes only help if the water can leave the pot. There is a second payoff for the same decision: CTAHR asks for well-drained soil in a relatively dry or well ventilated place specifically to shorten leaf wetness after rain, so siting for drainage lowers rust pressure at the same time.

No spray for this one. Prevention is the control.

Verified · 5 sources View

Seasoned

Where to plant next year

Crop rotation

Lemongrass is a grass that lives for years in one spot, so you do not move it around each season like a vegetable. Plant it in a sunny, rich, well-drained place and divide the clump every few years to keep it strong.Lemongrass belongs to the true grass family, Poaceae, unrelated to the mints, carrots, or nightshades of a typical vegetable rotation. Because it is a perennial clump held for several years and divided to renew, it sits outside the annual crop-rotation cycle. The practical placement rule is simply full sun, rich soil, and good drainage; every few years, lift and divide the clump to keep the center vigorous.

Family

Grass family (Poaceae)

Avoid following

Lemongrass is a perennial that stays in one place for years, so you do not rotate it like an annual vegetable. Just give a new clump a sunny, rich, well-drained spot.As a long-lived perennial clump, lemongrass is not part of an annual rotation; it holds its spot for years and is renewed by division rather than replanted each season. If starting a new clump, simply choose a sunny, rich, well-drained site.

Plant after

Any well-drained, fertile, sunny site (perennial; not rotated annually)

Verified · 2 sources View

Read the full methodology →

Spot a data point that doesn't match your experience? Submit a correction; accepted corrections earn full author credit on the page.

Lemongrass

What's happening right now

Your zone, at a finer grain

Planting calendar

Planting calendar

Planting calendar

Planting calendar

Planting calendar

Planting calendar

Planting calendar

Planting calendar

Planting calendar

Seed to garden

The growing journey

Your soil

Identify yours

What this crop wants

If your soil doesn't match

Containers and raised beds

Care guide

Yes, 3 gallons and up

Soil pH for lemongrass

Watering

Feeding

Companion planting

When to pick

What to expect

Recommended varieties

Storing your harvest

Common problems

Pests & diseases

Crop rotation

When plant taps you on the shoulder

Common questions

Got a question we missed?

Share a tip

Report a problem

Methodology & sources

Growing notes, weekly.