Thyme in USDA Zone 13 is a small perennial herb from the dry Mediterranean, and like rosemary it judges the tropics by drainage rather than temperature. Winter lows stay above 60°F and frost never arrives, so cold is no threat at all — the danger is wet soil and humid air, which rot thyme's roots and turn its tiny leaves black. Gardeners who plant thyme in heavy, waterlogged ground lose it in the first wet season. Gardeners who give it a pot, a raised bed or a gritty slope get a low, fragrant mat that lives for years and gives leaves in every month of the year.
Thyme is a small plant with an outsized kitchen role: a pinch of leaves flavours roasts, soups and stews, and the plant itself is a pretty edging for a sunny bed or a pot by the door. English thyme is the classic culinary type, and it copes with Zone 13 as well as any variety, provided the drainage is right.
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 | 14–21 days |
| Days to maturity | 70–90 days |
| Sowing | both |
| Planting window | Cooler, drier months to establish; perennial once established |
| Harvest | 70–90 days to first light picking; perennial harvest after that |
| Sun | full sun |
| Soil pH | 6.0–8.0 |
| Spacing | 9–12 inches |
| Water needs | low |
| Cold tolerance | hardy |
When to plant thyme in Zone 13
Plant thyme in the cooler, drier months, so the young plant can root well before the wettest weather. With 70–90 days to a first light picking, a plant set out in the cool season is established and spreading by the time the rains build, and after that it is a perennial — no replanting needed, just trimming and feeding. Avoid starting thyme at the beginning of the wettest months, when a young plant can sit in saturated soil. The planting calendar hub shows the Zone 13 year, and December in Zone 13 is a good start for a new plant.
Starting thyme in Zone 13
Start thyme from a young bought plant or a cutting rather than seed if you want a quick result: seed germinates in 14–21 days and grows slowly, while a nursery plant is already a small, usable clump. If you do sow, scatter the tiny seed on the surface of a gritty mix and barely cover it, keep it evenly moist but never wet, and be patient. Take cuttings from a healthy plant in the cool season, strip the lower leaves, and root them in a free-draining mix. Set the young plant out in its final spot, water it in once, and then water sparingly while it establishes. A pot or raised bed is the safest home in the tropics, because you control the drainage and can move the plant under cover in the heaviest rain.
Soil, spacing, sun and water
Thyme grows best in full sun, in poor, gritty, sharply drained soil with a pH of 6.0–8.0 — it even tolerates slightly alkaline soil, which few herbs do. Rich, wet soil is the enemy: it makes soft, sappy growth that rots, while lean, gritty soil makes a compact, fragrant plant. Mix coarse sand or fine gravel into the planting hole, and use a raised bed or pot where drainage is doubtful. Space plants 9–12 inches apart so air can move between them, using the plant spacing calculator to plan. Thyme needs low water once established: water young plants until they root, then water only when the soil is dry, and water at the base in the morning so the tiny leaves stay dry.
Companion planting
Good companions for thyme include tomatoes, peppers, marigolds and cabbage, and thyme is a classic companion for brassicas, partly because its scent is said to confuse pests. Rosemary is the natural partner, sharing the same love of sun and sharp drainage, and oregano grows the same way in the same dry corner.
Pests and problems
The common pests to watch for with thyme are aphids, spider mites and whiteflies. Inspect the tiny leaves regularly and wash aphids off with a gentle jet of water, taking care not to flatten the plant. The pest identifier helper can help if you are unsure what you are seeing. In Zone 13, root rot and fungal disease from wet soil matter more than insects: a thyme plant that turns brown and dies from the centre out is usually drowning, not being eaten. Sharp drainage, wide spacing for airflow, morning watering at the base and never overwatering are the real defences, and a plant in a pot under cover in the wettest weeks often outlives one in the open ground.
Harvest and storage
Harvest thyme by snipping sprigs from the tips, starting with a light picking about 70–90 days after planting and taking more as the plant spreads. Never take more than a third of the plant at once, and pick in the morning, when the oils are strongest. The leaves are tiny, so strip them from the stem by running your fingers down it, and use them fresh or dried. For storage, thyme dries beautifully: hang small bundles in a dry, airy place out of direct sun, then strip the leaves into a jar, where they keep their flavour for months. Trim the plant lightly after flowering to keep it compact and stop it going woody in the centre, and divide or replace old, woody plants every few years. Oregano dries in exactly the same way, so the two harvests can be handled together.
Frequently asked questions
When should I plant thyme in Zone 13?
In the cooler, drier months, so the young plant establishes before the wettest weather. Once established, thyme is a perennial and needs no replanting.
Why did my thyme turn brown and die in Zone 13?
Almost always wet soil. Thyme comes from dry, rocky ground and its roots rot in waterlogged soil.
What soil and spacing does thyme need in Zone 13?
Full sun, lean gritty well-drained soil with a pH of 6.0–8.0, spaced 9–12 inches apart.
How do I harvest thyme?
Snip sprigs from the tips, never more than a third of the plant at once, and strip the tiny leaves from the stem.