Lemongrass is a tropical grass that feels right at home in Zone 9: it loves heat, grows into a tall, arching clump within a season, and gives you fresh stalks for Thai cooking and tea from summer until the first frost. In most of Zone 9 it behaves as a tender perennial — it may survive a mild winter, but a hard freeze can cut it to the ground, so many gardeners treat it as a warm-season annual and replant each spring.
One plant is usually plenty. A mature clump can be several feet wide, so give it space, and wear gloves when harvesting — the leaf edges are sharp.
Zone 9 at a glance
USDA Zone 9 covers the warmest parts of the southern United States, including much of Florida, southern Texas, southern Louisiana, southern Arizona and coastal California. Winters are mild, with average winter lows of 20 to 30°F, and the growing season runs nearly all year.
The average last spring frost in Zone 9 is Jan 30–Feb 15, and the average first autumn frost is Dec 1–15. These are USDA zone averages drawn from NOAA frost records, not exact dates for any one garden — always check your local extension service and the forecast before planting tender crops outside.
| Detail | Zone 9 guidance |
|---|---|
| Average winter low | 20 to 30°F |
| Average last spring frost | Jan 30–Feb 15 (average/range) |
| Average first autumn frost | Dec 1–15 (average/range) |
| 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 9
Plant lemongrass in Zone 9 after the average last frost — from March through May, once nights are reliably warm — so plants have the whole hot season to grow. Plants mature in 90–120 days to a first harvest of usable stalks, and seed germinates in 10–21 days, though most gardeners start from nursery plants or divisions, which are faster. The average last spring frost is Jan 30–Feb 15 and the average first autumn frost is Dec 1–15 — USDA zone averages, not exact dates, so check your local extension service and the forecast before planting tender crops outside. Lemongrass is tender: the first frost will brown the leaves, though the crown often survives a mild Zone 9 winter and regrows in spring. In the coldest parts of Zone 9, lift a division into a pot in autumn as insurance.
Work back from the frost dates rather than from a calendar date: the planting calendar hub gives the Zone 9 picture month by month. The month guides for March in Zone 9 and April in Zone 9 show what else is happening at planting time.
Starting lemongrass in Zone 9
Start lemongrass from nursery plants, divisions, or fresh stalks bought for cooking — a stalk with a firm base will root in water within a couple of weeks. If you start from seed, sow indoors in pots of seed-starting mix, keep the soil warm and moist, and be patient — germination takes 10–21 days and seedlings grow slowly at first. Harden plants off for a week before setting them out, and plant only after the last frost, when nights are warm. Space plants 24–36 inches apart: a lemongrass clump grows fast and wide in Zone 9 heat. Plant it in a large pot or a defined bed edge, since it can crowd out neighbours.
Soil, spacing, sun and water
Lemongrass needs full sun and rich, moisture-holding soil with a pH of 6.0–7.0. Dig in plenty of well-rotted compost before planting — it is a hungry grass and pale, thin growth usually means it needs feeding. Space plants 24–36 inches apart so air can move through the clump. Water needs are moderate: keep the soil evenly moist, especially in summer heat, and water deeply at the base. Mulch thickly to hold moisture and keep roots cool. Lemongrass grows well in a large pot on a sunny patio, which also lets you move it under cover if a cold snap is forecast.
Companion planting
Good companions for lemongrass include tomatoes, peppers, marigolds and cabbage, and lemongrass itself is a useful companion — its scent is said to deter pests, and it makes a good windbreak at the edge of a vegetable bed. Basil is another warm-season plant that shares the sunny Zone 9 bed, and our guide to when to plant basil in Zone 9 shows how its timing lines up with lemongrass. Rotate annual crops each year, but lemongrass is a clump-forming perennial — choose its spot with the long term in mind, and keep it away from delicate herbs it might shade. 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, though a vigorous clump is rarely troubled. Aphids cluster on young growth — wash them off with water. Slugs nibble young shoots, especially after rain; hand-pick them after dark. Cutworms can sever young seedlings at soil level; a cardboard collar helps. In Zone 9, cold is a bigger threat than any pest — a hard freeze can kill the crown, so mulch thickly in autumn or lift a division into a pot.
Harvest and storage
Harvest lemongrass 90–120 days after planting, once stalks are at least half an inch thick at the base. Pull or cut outer stalks at ground level, peel away the tough outer leaves, and use the pale, tender base for cooking. Pick little and often — regular harvesting keeps the clump productive. Use stalks fresh, or chop and freeze them, or dry the leaves for tea. In Zone 9, harvest through summer and autumn; before the first frost, cut the clump back and mulch thickly, or lift a division into a pot to overwinter indoors.
Frequently asked questions
When should I plant lemongrass in Zone 9?
Plant after the average last frost, from March through May. Plants mature in 90–120 days. It is tender — frost browns the leaves, though the crown often survives a mild Zone 9 winter.
Will lemongrass survive winter in Zone 9?
Often, yes — the crown usually survives mild winters (average lows 20 to 30°F) and regrows in spring. In the coldest spots, lift a division into a pot in autumn as insurance.
How do I start lemongrass?
Easiest from a nursery plant, a division, or a fresh cooking stalk rooted in water. Seed germinates in 10–21 days but is slower and less reliable.
How much space does lemongrass need?
A lot — 24–36 inches between plants. A mature clump can be several feet wide, so give it a large pot or a defined bed edge.