Lemongrass in USDA Zone 13 is one of the best-matched plants in this whole series, because lemongrass is a tropical grass and Zone 13 is the tropics. Winter lows stay above 60°F, the zone is frost-free year-round, and the warm, humid conditions that defeat Mediterranean herbs are exactly what lemongrass wants. It grows year-round, fast and lush, and a single clump can become a large, fountain-like plant that gives stalks for cooking and leaves for tea in every month of the year.
Lemongrass is the essential flavouring for Thai, Vietnamese and Caribbean cooking, with a bright citrus scent and no bitterness, and it is also a handsome ornamental grass for a sunny corner. It needs space — a mature clump can be waist-high and a metre across — so give it room, or grow it in a very large pot. Plant it once, and in Zone 13 it will look after itself for years.
Zone 13 at a glance
USDA Zone 13 is the hottest zone in the system, with average winter lows above 60°F, covering tropical places such as Puerto Rico, Hawaii and Guam. It is frost-free all year, so there is no last spring frost and no first autumn frost to plan around. Zone 13 has no frost dates to work from, so plant by heat and by the wet and dry seasons instead. These are zone averages, not promises for any one garden — check your local extension service.
| Detail | Zone 13 guidance |
|---|---|
| Winter low | Above 60°F |
| Frost | Frost-free year-round (no last or first frost dates) |
| Days to germination | 10–21 days |
| Days to maturity | 90–120 days |
| Sowing | start indoors |
| Planting window | Year-round; thrives in Zone 13 heat and humidity |
| Harvest | 90–120 days to first cutting; cut stalks continuously after that |
| 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 13
Plant lemongrass year-round in Zone 13 — there is no wrong month, because the zone is frost-free and lemongrass loves heat and humidity. Set a new clump out whenever you are ready, and with 90–120 days to a first cutting it will be established and harvestable within a few months, then keep growing indefinitely. The most useful calendar for lemongrass in the tropics is a maintenance one: divide an overgrown clump every year or two, cut back dead leaves in the cool season, and harvest stalks whenever the kitchen needs them. The planting calendar hub shows the Zone 13 year, and June in Zone 13 is a good picture of lemongrass at full vigour.
Starting lemongrass in Zone 13
Start lemongrass from a young bought plant or from a division of an established clump — both are fast and reliable, and they guarantee the culinary type. Seed germinates in 10–21 days but grows slowly, and seed-grown plants are variable, so most gardeners start with a plant. You can also root a fresh stalk from the market: trim the top, stand the base in water until roots appear, then pot it up. Set the young plant out in its final spot, water it in well, and keep it watered while it establishes. Give it room from the start, because a lemongrass clump expands steadily and will crowd its neighbours within a year.
Soil, spacing, sun and water
Lemongrass grows best in full sun, in rich, well-drained soil with a pH of 6.0–7.0. It is a hungry grass, so dig in plenty of well-rotted compost before planting and feed it again each year, and it will grow faster and thicker for it. Space plants 24–36 inches apart — a mature clump is large — using the plant spacing calculator to plan. Lemongrass needs moderate water: steady moisture keeps it lush, and it wilts and thins out if it dries for long, so water at the base in the morning and mulch thickly to hold moisture. In the wettest months it will look after itself; in a dry spell, water it like a vegetable, not like a Mediterranean herb.
Companion planting
Good companions for lemongrass include tomatoes, peppers, marigolds and cabbage, and lemongrass earns its place at the edge of a vegetable bed because its strong citrus scent is said to confuse some pests. Basil is a good neighbour in the warm-season garden, and mint in its own pot nearby makes a good partner for a tropical herb corner.
Pests and problems
The common pests to watch for with lemongrass are aphids, slugs and cutworms. Inspect the clump regularly, wash aphids off with a strong jet of water, and pick slugs by hand in the evening. The pest identifier helper can help if you are unsure what you are seeing. Lemongrass is a tough, vigorous plant and usually outgrows minor trouble, but in Zone 13 the most common problem is not a pest at all — it is a clump that has grown too large, gone woody in the centre, or been left undivided for years. Cut out dead leaves, divide the clump in the cool season, and replant the strongest outer pieces in fresh, compost-rich soil.
Harvest and storage
Harvest lemongrass by cutting stalks at the base, starting with a light cutting about 90–120 days after planting and taking more as the clump grows. Choose thick, pale stalks from the outside of the clump, cut them low with a sharp knife, and trim off the leafy top and the tough outer layers to reach the tender, pale heart — that is the part you cook with. The leaves can be used fresh for tea or dried, and they are fragrant in the garden even when you are not harvesting them. For storage, stalks keep for weeks in the fridge, and they freeze well chopped or whole. Divide an overgrown clump every year or two, replanting the strongest pieces, and a Zone 13 lemongrass clump can feed a kitchen for years. Spaghetti squash grows well at the edge of the same warm-season garden.
Frequently asked questions
When should I plant lemongrass in Zone 13?
Any time — lemongrass grows year-round in Zone 13 because the zone is frost-free and lemongrass is a tropical grass that loves heat and humidity.
How much space does lemongrass need in Zone 13?
A lot: 24–36 inches between plants, and a mature clump can be waist-high and a metre across.
What soil and spacing does lemongrass need in Zone 13?
Full sun, rich well-drained soil with a pH of 6.0–7.0, spaced 24–36 inches apart.
How do I harvest lemongrass?
Cut thick, pale stalks at the base with a sharp knife, trim off the leafy top and tough outer layers, and use the tender pale heart.