Lemongrass (Cymbopogon citratus) is an ornamental grass grown as a culinary herb. Clumps form from bulb-like bases and send up coarse, wide blades that sway in the wind. The plant is a tropical or subtropical perennial that can be grown in the ground, in containers, or even in water. Gardeners in temperate zones usually treat it as an annual, because frost kills the top growth. Since it grows fast, lemongrass can fill tight spots along fences and foundation beds where slower herbs struggle to establish.
A mature clump reaches 2 to 4 feet tall and 2 to 4 feet wide. It needs full sun, moist but well-draining soil, and a neutral to acidic pH. It is hardy in USDA zones 10 and 11 and native to Asia. The stalks show up in kitchens across Southeast Asia, and the same plant appears in aromatherapy, soaps, and candles. Keep in mind that lemongrass is toxic to pets, so place it away from dog runs and cat paths.
When and Where to Plant Lemongrass
Timing decides success more than any other factor. Wait until the danger of frost has passed, and preferably until nighttime temperatures hold at 60°F or warmer. Seeds started indoors go into flats about three weeks before the last expected frost date. Home gardeners are raising the profile of lemongrass as a dual-purpose ornamental, and the plant rewards basic site preparation at planting time.
Choosing a Planting Site
Choose a spot with at least six hours of direct sun. Soil should stay moist but never soggy, so avoid low pockets where water collects after rain. A neutral to acidic pH between 5.5 and 7.5 suits the plant well. Wind protection helps in exposed yards, because tall blades can snap in strong gusts.
Spacing and Companion Placement
Give each clump room to reach its mature width. Space plants about 3 feet apart in beds, or 2 feet apart if you plan to harvest heavily and keep the clumps small. Lemongrass pairs well with basil, ginger, and peppers, which share its sun and moisture needs.
Planting Steps
- Harden off transplants for 7 to 10 days by setting them outside for a few hours each day.
- Dig a hole twice the width of the root ball and roughly the same depth.
- Set the crown at soil level; burying it deeper invites rot.
- Backfill, firm the soil, and water thoroughly.
- Spread a 2-inch layer of mulch to hold moisture and suppress weeds.
Frost dates set the whole schedule. In zones 10 and 11, planting can happen any month, while gardeners in zones 6 and colder should wait until the soil warms in late spring. A soil thermometer reading 65°F or warmer at a 4-inch depth is a reliable go signal.
Soil, Water, and Feeding Requirements
Lemongrass is not a fussy feeder, but it responds quickly to consistent moisture and regular nitrogen. The plants grow fast from late spring through early fall, and that growth spurt needs fuel.
Soil Profile and Drainage
Loamy soil with good organic content gives the best balance of moisture retention and drainage. In heavy clay, raise the bed or amend with compost before planting. In containers, use a quality potting mix with perlite so the roots never sit in standing water.
If the native soil runs alkaline or sandy, work in compost and an organic soil acidifier a few weeks before planting. Reapply compost as a topdress each spring; the organic matter feeds the soil food web that keeps the clump green.
Watering Schedule
Aim for 1 to 2 inches of water per week during the growing season, applied at the base rather than over the leaves. In hot, dry spells, check the soil every couple of days; the clump shows stress as curled or browning leaf tips.
Signs of Overwatering
Yellow lower blades, soft stems, and a sour smell from the soil all point to excess moisture. Cut back watering and improve drainage before the bulb rots.
| Stage | Fertilizer | Rate | Frequency |
|---|---|---|---|
| Planting | Balanced 10-10-10 | 1 tablespoon per plant | At transplant |
| Active growth | High-nitrogen 21-0-0 or compost tea | Per label | Every 4 weeks |
| Midsummer | Liquid seaweed | 1 ounce per gallon | Every 2 to 3 weeks |
| Late fall | None | Stop feeding | 6 weeks before frost |
Growing Lemongrass in Containers and Indoors
Container growing solves two problems at once: it limits clump size, and it makes overwintering simple because the whole pot moves indoors. Patio growers in cold zones treat lemongrass as a mobile plant that follows the sun.
Pick a pot at least 12 inches deep and 12 inches wide; those simple profile standards give the bulb room to expand and keep the clump from tipping in wind.
Container Mix and Drainage
Use a potting mix amended with perlite or coarse sand. The pot needs drainage holes, and the saucer should be emptied after watering. A light-colored pot stays cooler in summer and reduces root stress.
Containers dry out faster than garden beds, so check the pot every day during summer heat. Water until it runs from the drainage holes, then let the top inch of mix dry before the next watering.
Indoor Growing Conditions
Indoors, lemongrass wants the brightest window you have, ideally south-facing. Supplement with a grow light for 12 to 14 hours per day in winter. A humidity tray or occasional misting keeps leaf tips from browning in heated rooms.
Repotting and Dividing
Repot every one to two years in early spring. When the clump fills the pot, divide it into sections of three to four stalks and replant the divisions in fresh mix.
Harvesting, Pruning, and Propagation
Harvest begins once stalks reach about half an inch thick, usually 8 to 10 months after planting in warm zones and sooner in the first season for plants started from large divisions. A vigorous clump is a high-profile addition to any border, and regular cutting keeps it that way.
How to Harvest
- Choose outer stalks that are at least half an inch thick.
- Cut at soil level with a sharp knife.
- Trim away the leaf blades and keep the pale bulbous base.
- Rinse, slice, and use fresh, or freeze the lower sections.
Fresh stalks keep for about two weeks in the refrigerator when wrapped in a damp paper towel. For longer storage, slice the pale bases and freeze them, or dry the leaves for tea. The tough outer layers still hold flavor after months in the freezer.
Pruning and Division
Cut the whole clump back to 6 inches in late fall or early spring to clear dead blades. Every two to three years, lift the clump and discard the woody center, replanting the healthy outer pieces.
Propagating by Division
Division is the fastest way to multiply lemongrass. Slice the clump with a shovel, keeping three to four stalks per division, and replant immediately at the same depth.
Pests, Diseases, and Common Problems
Lemongrass has few serious enemies, but a handful of issues show up in gardens and on windowsills. A few pitfalls to avoid include planting in shade, letting the root zone dry out, and skipping fall cleanup, since each invites a specific problem.
Fungal Issues
Rust appears as orange pustules on the leaves, usually when airflow is poor or foliage stays wet. Blight causes brown spots that spread from the leaf tips. Improve spacing, water at the base, and remove affected blades promptly.
Indoor Pests
Spider mites and aphids move in when plants come indoors for winter. Knock them off with a strong spray of water, or treat with insecticidal soap, and quarantine new plants for a week before placing them near other houseplants.
Yellowing leaves indoors usually mean the plant is root-bound, under-watered, or sitting too far from light. Check the roots first, then adjust watering and move the pot closer to the window before reaching for fertilizer.
Prevention Checklist
- Plant in full sun with 3 feet between clumps.
- Water at the base, not over the leaves.
- Remove dead or spotted foliage weekly.
- Inspect indoor plants before bringing them inside.
Overwintering and Cold-Climate Care
In zones 10 and 11, lemongrass stays in the ground year-round. Everywhere else, plan a winter strategy before the first frost. Moving a clump from garden to container is a clean profile transfer: dig wide, keep the root ball intact, and pot it immediately.
Overwintering Options
- Grow it as an annual and replant each spring.
- Move potted plants indoors to a bright window.
- Dig clumps, trim blades to 6 inches, and store bare-root in a cool garage at 40 to 50°F.
- In zones 8 and 9, cut back and mulch heavily with straw or leaves.
Zone 7 gardeners can try leaving a well-mulched clump in the ground with a heavy straw cover, but potted backups are safer. A container plant brought indoors costs nothing and guarantees next season’s supply.
Spring Revival
Bring stored clumps out after the last frost, water deeply, and feed with a balanced fertilizer. Divisions taken in spring establish fast and fill a bed by midsummer.
From a single division, one clump can supply stalks for tea, curries, and broths all season. Keep the soil consistently moist, cut often, and divide before the center dies out, and lemongrass becomes one of the easiest tropical herbs to grow in almost any climate.