Holy basil

Holy basil: how do you recognise it?

Habit

Bushy subshrub about 50 cm tall and 30 cm wide, with hairy, square stems. An annual here.

Leaves

Oval, 2–5 cm, slightly hairy with a toothed edge; green (‘Rama’) or purple (‘Krishna’); in opposite pairs.

Flowers

Small pink-purple to lilac flowers in whorls on long spikes, from July to September; they attract bees.

Scent and flavour

Peppery, with a hint of clove and mint; sharper than sweet basil.

Roots

Fibrous and shallow; in a pot it needs a pot at least 20–25 cm wide.

Flowering: July–September · Harvest and fruit: July–September · Sowing: March–May · Plants: May–June · Pruning: June–August

Why grow it?

• A distinctive, peppery fragrance with a hint of clove and mint, different from sweet basil.
• Suits Thai stir-fries (kaphrao) and teas, fresh or dried.
• An attractive ornamental with green or purple leaves and pink-purple flower spikes that attract bees.
• Easy to grow in a pot on a sunny windowsill, in a conservatory or on a warm terrace.
• Quick to grow from seed: within a few months you have a full plant.

Holy basil: where does it grow best?

• Full sun and warmth: a sunny, sheltered spot, a conservatory or a sunny windowsill.
• Humus-rich, loose, free-draining soil; sand or loam, acid to chalky.
• Moderately moist: do not let the soil dry out and do not keep it soggy.
• Sheltered from wind and cold nights; it needs at least 5 °C and does best above 15 °C.
• Space plants 25–30 cm apart; in a 20–25 cm pot, one plant per pot.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Normal

Size

0.5 m tall, 0.3 m wide

Hardiness

Frost tender: overwinter indoors (above 5 °C)

Goes well with

• Chilli pepper: Likes the same warmth and goes in the same Thai dishes.
• Lemongrass: A second Asian herb for a pot on the terrace.
• Sweet basil: Side by side in separate pots for different dishes.

Holy basil: when and how to plant it?

Plant in May–June.

1. Sow in March–May indoors at 20–25 °C. The seeds are very small: press them onto moist seed compost and barely cover them. They come up in 1–2 weeks.
2. Prick out the seedlings when they have two true leaves and put them in small pots in a bright, warm place.
3. In May get them used to the outdoors gradually and put them outside only after mid-May (after the Ice Saints), when nights are warmer than 10 °C.
4. Plant them 25–30 cm apart or in 20–25 cm pots, at the same depth as in the pot.
5. Water in generously straight away and spread a thin layer of mulch around the plant.

Care

Water

Regularly, in the morning at the base; keep the soil lightly moist but never wet. Do not water over the leaves.

Feeding

Sparingly: a little organic liquid feed every 3 weeks. Too much fertiliser gives soft leaves with less aroma.

Pinching out

Pinch out the tips regularly, above a few leaves: this gives a bushy plant and new leaves.

Harvesting

Pick the leaves in the morning and never take more than a third of the plant at once. Use them fresh in dishes; for tea you can dry the leaves.

Flower spikes

Let some flower for the bees; if you want leaves, pinch them out.

Tip: Grow it in a pot on a sunny windowsill or in a conservatory and pinch out the tips regularly. Pick the leaves fresh for stir-fries or dry them for tea.

Holy basil: when to prune it?

Pruning months: June–August.

When: From June to August pinch or snip out the tips regularly, as soon as the plant is 15–20 cm tall.

How:

• Pinch out the tip of each shoot, just above a pair of leaves.
• Remove flower spikes if you mainly want to harvest leaves; this keeps the plant bushy.
• Never harvest more than a third of the plant at once.
• Towards the end of the season, let a few spikes flower for the bees and for seed.

Caution: It is an annual here and dies at the first frost. Harvest everything before the first night frost.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

March–May indoors at 20–25 °C, the seeds barely covered. Keep the seed compost lightly moist and warm.

Cuttings

In August–September cut a tip of 8–10 cm, remove the lower leaves and stand it in a glass of water; roots form in 1–2 weeks. Pot up the cuttings for the windowsill.

Holy basil: how does it get through the winter?

Hardy to 5 °C: protect in harsh winters.

• Not hardy: here it is an annual and dies at the first frost. It needs at least 5 °C and grows best above 15 °C.
• In September harvest everything before the first night frost.
• To keep it indoors: in September put a potted plant or cuttings on a warm, very bright windowsill (15–20 °C) and water moderately. It grows more slowly in the short days.
• Keep seed from a healthy plant in a dry, cool place for the next sowing.

Diseases and pests

• Cold damage: Leaves turn black or drop below 10 °C. Keep it warm and put it outside only after mid-May; bring it indoors on cold nights.
• Downy mildew: Yellow patches on the leaves and a grey-purple fuzz underneath, especially in damp summers. Water at the base, space plants widely and remove affected plants.
• Aphids and whitefly: On young shoots, especially indoors. Spray off with water, use yellow sticky traps or rub them off.
• Root rot: Yellow, limp leaves from wet roots, especially in winter. Use free-draining compost, a pot with holes and do not overwater.

Through the year

• March: Sow indoors at 20–25 °C.
• April: Sow and prick out. Keep somewhere bright and warm.
• May: Last sowing. After mid-May, harden off gradually and plant out.
• June: Plant out. Pinch out tips and start harvesting.
• July: Harvest. Pinch out flower spikes if wanted. Water.
• August: Harvest. Let some flower for the bees. Take cuttings.
• September: Last harvest. Bring cuttings or potted plant indoors.
• October: Harvest everything before the first frost. Clear away.

Edible and useful

Leaves (July–September)

Cut the leafy tips from July to September; pinch out the flower buds so the plant keeps making leaves. Holy basil (tulsi) tastes spicy and peppery, of cloves and mint. In India it is drunk as a tea; in Thailand it is stir-fried in a hot dish (pad kra pao).

Storing

The leaves are best fresh; they keep for a few days with the stems in a glass of water on the worktop (not in the fridge, where they turn black). For tea, dry the leaves on a rack somewhere warm and shady and keep them in a closed jar.

Caution: In normal amounts, tulsi tea is safe for most people. Do not drink it during pregnancy, and take care with blood thinners or diabetes medication; if in doubt, ask your doctor. Holy basil is not hardy and likes warmth: put it outside only after mid-May, preferably in a pot in a sunny, sheltered spot.

Eating and using is at your own risk: see the terms of use.

Recipes

• Tulsi tea (Tea · 2 cups · 10 min)
• Spicy holy basil stir-fry (pad kra pao) (Dish · 2 people · 20 min)

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The word tulsi is often translated as ‘the incomparable one’; in India the plant is regarded as sacred and grows in pots near houses and temples.
• The species used to be called Ocimum sanctum; sanctum means ‘holy’ in Latin.
• In Thailand it is called kaphrao and is the basis of the famous stir-fry pad kaphrao.