Thai basil

Thai basil: plant 30 cm (12 in) apart in the row and 45 cm (18 in) between rows, 4 per square. No known bad neighbours.

Key facts

Spacing in the row	30 cm (12 in)
Between rows	45 cm (18 in)
In a 30 cm (1 ft) square	4 per square
Sun	Full sun, 6–8 hours a day
Root depth	15 cm (6 in)
Height when grown	35 cm (14 in)
Crop rotation group	Herbs, flowers and perennials
Support	None needed

Sowing and germination

How it is started	Sown straight into the bed, started in trays
Seeds per hole	3
Plants kept after thinning	1
Seeds per metre of row	12
Sowing depth	0.3 cm (0.1 in)
Soil temperature	from 18 °C, best 22–28 °C
Days to emerge	7–21 days
Light while germinating	Needs light, barely cover
Before sowing	nothing needed
When to sow	Indoors 6 weeks before the last frost; outdoors after the last frost; soil at least 16 °C

From seedling to plant

After emergence	16–22 °C; take the cover off as soon as they show
Pricking out	at 2 true leaves
Takes transplanting	Easily
Hardening off	7–10 days
Life cycle	Annual
Cold tolerance	Tender, hurt by frost
Soil	Light, sandy, free draining, pH 6–7.5
In a pot	5 L, 20 cm (7.9 in)
Watering	Water when the soil is dry two fingers down
Feeding	Little; at planting
Support and training	None needed; pinch the tips

Harvest and planning

Days to first harvest	50–70 days, from sowing
Ready when	The leaves are big enough to use
Harvest window	Picked again and again, 8–20 weeks
Typical yield	0.2–0.6 kg per plant
Botanical family	Lamiaceae
Watch out for	Aphids, powdery mildew

Plan Thai basil in your garden

Open the free planner, drop Thai basil onto a bed and see how many plants fit.

Start Planning Your Garden

Sowing and harvest

Sow indoors	Mar–Apr
Sow outdoors	May–Jun
Harvest	Jun–Sep

My dates for this crop

My country Last spring frost where I live

Give the date once and this page, the sowing calendar and the planner all follow it.

Months for a temperate climate: about a month later in the north and a month earlier in the south. Give your own last frost date for exact dates.

What to plant next to Thai basil →

From the same family

Plants of the Lamiaceae family share diseases and pests, so they follow each other in the rotation only after a break.

Grown much the same way

Crops that need about the same room and care, from another family.

Sources

The values on this page marked as checked come from these sources: spacing, sowing depth, germination, soil, timing and safety notes, each against the source named here.

Culinary Use and Culture of Herbs (from the California Master Gardener Handbook; R10/2019) — UC Cooperative Extension, Master Gardeners of Orange County for: between rows, spacing in the row; checked 2026-10-30

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