Lemongrass

Quick facts

Category

herbs woody

Difficulty

beginner

Days to harvest

120 to 240 days

Harvest type

cut leaves, plant regrows for repeated harvests

Spacing

40 cm between plants

Environment

Temperature

18–32°C

pH

5.5 to 7

EC (hydroponic)

1.5 to 2.5 mS/cm

Daily light

18 to 28 mol/m²/day (strict, will fail outside this range)

Climate and zones

USDA zones

10 to 13 (winter low around -1°C or warmer)

Frost tolerance

frost sensitive (dies at first frost)

Season

year-round tropical (needs consistent warmth)

Viable growing environments:

• outdoor in growing season (annual)
• heated greenhouse
• indoor (heated home)
• indoor hydroponics under grow lights

USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.

Growing systems

Lemongrass works in:

• media bed (ebb and flow)
• wicking bed
• soil bed

Root mass is heavy - thin-channel systems (NFT, vertical towers) can't hold this crop mechanically, hence the system list above.

Growing media

The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (lemongrass works in the media listed below).

Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.

Nutrient demand by stage

NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.

Companion-growing notes

• High transpiration. Reservoir level will need regular top-ups during fruiting or flowering.

Aquaponics suitability

Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.

Care notes

One of the easiest tropical crops for container or hydroponic growing. Large container (10 L) or media bed. EC 1.5-2.5 mS/cm. pH 5.5-7.0. Temperature: 20–35°C (tropical; growth stops below 15°C, frost kills the plant). High light (DLI 16-25 mol/m2/day; supplemental lighting extends production in northern climates). Propagation is simple: buy fresh lemongrass stalks from a grocery store (with the base intact), place them in water until roots develop (7-14 days), then plant. Each rooted stalk develops into a clump of 10-20+ stalks within a season. Harvest individual stalks by pulling and twisting them from the outer edge of the clump. Use the bottom 10–15 cm of each stalk (the tender, pale interior); bruise it by smashing with the flat of a knife before adding to soups and curries. The clump regenerates continuously. Bring containers indoors before first frost; the plant survives winter in a bright window as long as it stays above 10°C. For Southeast Asian cooking, fresh lemongrass is one of the most valuable crops you can grow; a single clump provides year-round supply.

Further reading

• Best crops for hydroponic beginners
• The Kratky method: grow lettuce with zero electricity