Ocimum basilicum var. thyrsiflora
Thai basil
Common names: Thai sweet basil, Asian basil
At a glance
- Light
- Full sun
- Spacing
- 25 cm, rows 30 cm
- Lifespan
- Annual
- Sowing
- Apr–Jun
- Harvest
- Jun–Sep
- Hardiness
- Cold damage below 8 °C
- Water need
- High
Photo: Castielli · CC BY-SA 3.0 · Source
This description was machine-translated.
Description
Thai basil, botanically Ocimum basilicum var. thyrsiflora, is the Southeast Asian form of basil. It can be recognized by its violet, angular stems, narrow, glossy green leaves with a slightly serrated margin, and purple flower spikes that stand above the foliage from July onward. The plant grows bushy and reaches 40 to 60 cm in height. Its aroma is reminiscent of anise and licorice with a fine pungency and differs clearly from Italian basil. In Vietnamese and Thai cuisine it is served fresh with pho and used to flavor curries and wok dishes. The leaves tolerate heat somewhat better than those of Italian basil, but they should still be added just before serving. On balconies and terraces it is also an attractive ornamental plant, and bees and bumblebees visit its flowers.
Care instructions
Place Thai basil in a warm, sunny, wind-sheltered spot, either in a bed or in a pot against a south-facing wall. Set young plants outside only after the Ice Saints in mid-May, when nights no longer fall below 10 °C; before that the plant stands still and becomes sickly. Water regularly in the morning directly at the roots and keep the foliage dry, since wet leaves promote powdery mildew. It does not tolerate waterlogging, so a pot needs a drainage hole. Once the plant reaches 15 cm in height, pinch out the shoot tips above a pair of leaves so it branches into a bushy form. Harvest the same way, taking whole shoot tips rather than single leaves, which keeps the plant dense. Cutting off flower buds regularly yields more foliage, though you can leave a few flower spikes standing for the bees. Young plants attract slugs; a slug collar and collecting them in the evening will protect them.
The care notes were machine-translated from German.
Garden year
SowingApr–Jun
HarvestJun–Sep
FloweringJul–Sep
Germination
- Soil temperature
- from 15 °C, ideally 24 °C
- Days to sprout
- 5 to 14 days
- Light
- Needs light to sprout
- Sowing depth
- Press in, don't cover
- How to start
- Start indoors, then plant out
Soil & site
Soil pH
Soil type
humus-rich, well-drained, nutrient-rich
Thai basil likes loose, humus-rich soil that warms up quickly in the sun. A bed with mature compost suits it well; in a pot, use good-quality herb compost and mix in some sand. Waterlogging makes the roots rot. So provide a drainage hole and a layer of gravel at the bottom of the pot, and on heavy soils work in plenty of sand. Cold, wet soil slows the plant down a lot, so it is better not to plant it out before mid-May.
Feeding
Medium feeder
Months
May–Aug
In the bed it is enough to work in some mature compost before planting. In a pot or box the soil is used up faster: from June to August, add a mild organic liquid fertiliser to the water every two weeks. Too much fertiliser makes the foliage soft and prone to fungal diseases. From September, do not feed any more.
Overwintering
Thai basil is an annual. Below about 10 °C it stops growing, the leaves become spotted or black, and frost finishes the plant at once. In the bed, you clear it away in autumn after the last harvest. Potted plants you bring in to a bright, warm windowsill in September; there they still give leaves for a few weeks, but rarely become strong again in the low-light winter. For seed, let individual flower spikes turn brown and rub out the seeds, but several basil varieties growing side by side readily cross.
Propagation
Methods
- From seed
- Cuttings
You start Thai basil from seed under cover from April. The fine seeds germinate in light: scatter them on moist seed compost, press them down and cover them with no more than a very thin layer. At 20 to 25 °C the first seedlings appear after one to two weeks; below 18 °C it takes longer or the seed rots. Prick out the seedlings as soon as the first true pair of leaves has developed, and keep them bright and warm. From the end of May you can also sow directly in the warm bed. Cuttings work as well: cut 10 cm shoot tips without flowers, remove the lower leaves and put them in a glass of water; roots form after one to two weeks.
Companion planting
Good neighbors
nightshade family (Solanaceae)
particularly well establishedYou will find that basil next to tomato and pepper improves taste and keeps whiteflies and aphids away.
For example PotatoTomatoSweet pepperCocktail tomatoEggplantCape gooseberry and 14 more species in the catalogue
Source: classic companion planting (DACH-Gartenpraxis)
cabbage family (Brassicaceae)
You will notice that the intense scent of basil, thyme, and others confuses the cabbage whitefly and keeps it away from the cabbage family.
For example White cabbageKohlrabiRadishKalebroccolicauliflower and 41 more species in the catalogue
Source: bio-gardening intercropping practice
Companion planting is partly traditional gardening lore. Where the reason is known, it is given.
Some of these explanations were machine-translated.
For your garden
Grow Thai basil yourself
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