Thai basil is a variety of sweet basil with purple stems, narrow leaves and a strong anise-liquorice scent. It holds up to heat better than Italian basil and is essential in Thai curries and Vietnamese pho.
What it is¶
Thai basil — horapha in Thai, húng quế in Vietnamese — is a variety of the same species as Italian sweet basil, selected over centuries in mainland Southeast Asia. It is easy to recognise: purple or maroon stems, smaller, narrower, slightly serrated leaves that are tougher and matt rather than glossy, and tight purple-bracted flower spikes.
It is not the same as holy basil (kaphrao), and the two are often confused in Western shops and recipes. The third common Thai basil, lemon basil (maenglak), is a different plant again, used mainly with fish and in soups, and its seeds are soaked to make the gelatinous "basil seeds" of Asian drinks and desserts.
Origins and history¶
Basil spread from India into Southeast Asia long ago, and the anise-heavy types seem to have been favoured and selected there. Beyond that, the history of this particular variety is poorly documented — it is a kitchen and market-garden plant rather than one written about by herbalists. It became familiar in the West from the 1970s onwards, as Thai and Vietnamese communities, restaurants and later supermarkets brought it to Europe, North America and Australia. Taiwanese cooks call a closely similar basil jiucengta ("nine-storey pagoda", after the tiered flower spikes) and use it generously in three-cup chicken.
Flavour and aroma¶
The dominant note is sweet anise or liquorice, much stronger than in Italian basil, backed by clove and a peppery, slightly camphor-like bite. The leaves are sturdier and their oil is less fragile, so the flavour survives a brief simmer or a toss in a hot wok that would flatten sweet basil. Raw, it is bold enough that a small handful perfumes a whole bowl of soup.
In the kitchen¶
- Curries: stirred into green and red curries, jungle curry and stir-fried curries just before serving.
- Pho and noodle soups: served raw, by the sprig, on the herb plate with bean sprouts, lime, chilli and culantro, for each diner to tear into the bowl.
- Stir-fries: aubergine, clams, squid and minced pork with chilli and garlic.
- Salads and rolls: fresh spring rolls and larb-style salads alongside mint and coriander.
- Taiwanese three-cup chicken: a large handful wilted in at the end.
Pick the leaves off the tougher lower stems. The flower buds are edible and pleasantly peppery.
📌 Pad kaphrao is not made with Thai basil
The famous Thai street dish phat kaphrao uses holy basil. Thai basil makes a tasty, sweeter version, and it is what most Western restaurants use, but it is a substitution.
Buying and storing¶
Look for firm, unwilted leaves with no black spotting and plenty of flower buds or tips. Like all basils it dislikes cold; keep it in a glass of water at room temperature, loosely covered, and use within three or four days. If you must refrigerate it, wrap it in a dry paper towel inside a bag in the warmest part of the fridge and use it within a day or two. It does not dry well; freeze leaves whole on a tray for use in curries, where appearance matters less (see freezing-herbs).
Substitutes¶
Italian sweet basil is the nearest widely available swap; add a crushed pinch of fennel seed or aniseed, or a few leaves of tarragon, to push it toward anise. Holy basil works in cooked dishes but tastes quite different — more clove and pepper, less liquorice. mint mixed with coriander gives freshness in salads and rolls, though not the aniseed note.
Pairs well with¶
Coconut milk, chilli, garlic, ginger, galangal, lemongrass, makrut lime, fish sauce, lime, coriander, mint, pork, chicken, seafood and aubergine.
Growing your own¶
Thai basil is grown exactly like sweet basil but is a little tougher and more tolerant of heat. Sow indoors at 20–25°C in spring and plant out only when nights stay above about 10°C; in cooler climates it does best in a greenhouse, conservatory or on a warm windowsill. Give it sun, free-draining compost and even moisture.
It flowers eagerly. Pinch out flower spikes and growing tips regularly for more leaves, or leave a few to bloom: bees love them and they look handsome. Cuttings of non-flowering shoots root in water within a week or two, and shop-bought bunches can often be rooted the same way (see propagating-herbs).