Lemongrass is one of the few herbs that genuinely loves Zone 12. This tall, lemon-scented grass is a staple of Thai and Vietnamese cooking, a useful tea plant, and — unlike the Mediterranean herbs — a true tropical perennial that grows bigger and better the hotter and wetter it gets. In the tropics it needs almost no encouragement: plant it once and it will be with you for years.
Like every crop in the tropics, lemongrass rewards gardeners who work with Zone 12's seasons — the cooler, drier months and the hot, wet months — rather than against them. The planting calendar hub gives the Zone 12 picture month by month, and our guide to when to plant lemongrass in Zone 11 shows how the timing shifts in a cooler zone.
Zone 12 at a glance
USDA Zone 12 covers the warmest, most tropical parts of the United States — Hawaii, Puerto Rico, Guam and the U.S. Virgin Islands. Winters are warm, with average winter lows of 50 to 60°F, and the growing season never really ends.
Zone 12 is frost-free year-round: there is no average last spring frost and no average first autumn frost. That means you plant by heat and by the wet and dry seasons, not by frost dates. These are USDA zone averages, not exact figures for any one garden — always check your local extension service and the forecast before planting.
| Detail | Zone 12 guidance |
|---|---|
| Average winter low | 50 to 60°F |
| Average last spring frost | Frost-free (no frost dates) |
| Average first autumn frost | Frost-free (no frost dates) |
| Days to germination | 10–21 days |
| Days to maturity | 90–120 days |
| Sowing | start indoors |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 24–36 inches |
| Water needs | moderate |
| Cold tolerance | tender |
When to plant lemongrass in Zone 12
Plant lemongrass in Zone 12 in spring or early summer, at the start of the warm, wet season, when the soil is warm and rain will help young plants root. Because Zone 12 is frost-free, with winter lows of 50 to 60°F, lemongrass is a perennial here — plant it once and it grows year-round, with no replanting needed. Stalks from the grocery store root in 10–21 days, and plants reach harvest size in 90–120 days. There is no frost date to work around; check your local extension service for the best local planting window. See the Zone 12 March planting guide for what else to plant that month.
Starting lemongrass in Zone 12
Start lemongrass indoors from seed, or far more reliably from stalks and divisions. Seed germinates in 10–21 days but is slow and variable; most gardeners start with fresh stalks from the market — trim the tops, stand the bases in water until roots appear, then pot them up. Or divide an established clump in spring, replanting divisions with roots attached. Space plants 24–36 inches apart: a single clump can grow four feet tall and three feet wide in a season. Give lemongrass a permanent spot, because a mature clump is hard to move.
Soil, spacing, sun and water
Lemongrass needs full sun and rich, moist, well-drained soil with a pH of 6.0–7.0. It is a hungry grass, so dig in plenty of compost before planting and feed through the growing season. Water needs are moderate — keep the soil evenly moist, especially while plants establish, and water in dry spells; lemongrass sulks in drought but rots if it sits in standing water. A thick mulch holds moisture and suppresses weeds around the clump.
Companion planting
Good companions for lemongrass include tomatoes, peppers, marigolds and cabbage. Its strong citrus scent is said to confuse pests, and it makes a useful windbreak or edging plant at the sunny side of a vegetable bed. Keep lemongrass away from low, shade-sensitive plants, which its tall clump will crowd out. The companion planting finder can suggest combinations for your whole bed.
Pests and problems
The common pests to watch for with lemongrass are aphids, slugs and cutworms. Aphids cluster on young shoots — wash them off with a strong jet of water. Slugs nibble young growth in wet weather, so keep mulch pulled back from the crown. Cutworms can sever young transplants at soil level, so protect new plantings with a cardboard collar. Lemongrass is otherwise one of the toughest plants in a Zone 12 garden, and its scent puts off many pests on its own.
Harvest and storage
Harvest lemongrass 90–120 days after planting, once clumps are well established. Cut outer stalks at the base with a sharp knife, taking the thick, pale lower stem — that is the part you cook with. Never take more than a third of a clump at once. The tender inner core is used fresh in cooking, while the leaves make a fragrant tea, fresh or dried. Divide crowded clumps every two to three years in spring to keep them vigorous, and replant the divisions. Use the herb drying calculator to work out drying times for your harvest.
Dividing lemongrass in Zone 12
A lemongrass clump doubles in size every year in Zone 12, and after two or three years the centre can go woody and unproductive. Dig the clump up in spring, split it into divisions with a sharp spade, and replant the healthiest outer pieces 24–36 inches apart. The divisions will root fast in warm soil and rain.
Give spare divisions to neighbours — every gardener in Zone 12 wants lemongrass, and a single clump can supply a whole street. Potted divisions also make excellent gifts, and a pot by the kitchen door keeps fresh stalks within reach all year.
For a related crop, see our guide to when to plant stevia in Zone 12.
Frequently asked questions
When should I plant lemongrass in Zone 12?
Plant in spring or early summer, at the start of the warm, wet season. Lemongrass is a perennial in frost-free Zone 12 — plant once and it grows year-round. Stalks root in 10–21 days and plants reach harvest size in 90–120 days.
Is lemongrass perennial in Zone 12?
Yes. With winter lows of 50 to 60°F and no frost, lemongrass survives winter easily and grows year-round. It only dies back if temperatures drop unusually low.
How big does lemongrass get?
A single clump can grow four feet tall and three feet wide in a season in Zone 12, so space plants 24–36 inches apart and give it a permanent spot.
Can I grow lemongrass from shop-bought stalks?
Yes — it is the easiest way. Trim the tops, stand the bases in water until roots appear, then pot them up and plant out once rooted.