October 10, 2024, 11:19 am | Read time: 6 minutes
Thai basil is becoming increasingly popular. Although it may seem exotic, the herb, which tastes of aniseed and licorice, can also be grown in our country. Read below how to grow it and what to look out for.
Thai basil is a collective term that essentially refers to three types of basil that are used in Thai cuisine: Horapa or Horapha (Ocimum basilicum var. thyrsiflora), Maenglak (Ocimum citriodorum) and Krapao (Ocimum tenuiflorum or Ocimum sanctum). Horapa basil is a slightly sweet aromatic herb that tastes of aniseed and licorice. This article is about this Thai basil, the most commonly used in Thailand. Maenglak basil tastes mildly of lemon and is therefore also known as lemon basil, while krapao basil tastes of cloves and allspice when slightly warmed. It is also known as Indian basil.
It is unclear where Thai basil originally comes from. However, it is thought to originate from India or Southeast Asia. Thai basil belongs to the basil genus, which comprises around 60 species and is a member of the labiate plant family.
Appearance and growth
Thai basil is a perennial, upright-growing, and densely branched semi-shrub that can grow up to 80 centimeters tall. The purple-colored stems usually have dark green leaves with clearly visible veins. Between June and August, Thai basil displays its pink-violet to purple-red flowers.
Sowing and planting Thai basil
Thai basil can be sown directly or grown in advance. Indoor cultivation should begin at the end of March at the earliest. If the plant is sown directly outdoors, this should not be done till the weather warms mid-May. Thai basil is a light germinator, so the seeds should not be covered with soil at all or only minimally. If you press the seeds down firmly on the soil, they will not float away so quickly when watered. At a temperature of around 20 degrees and slightly moist soil throughout, the seeds will germinate within two weeks.
Pre-grown or purchased young plants can be moved outdoors from mid-May when frost is no longer expected. The optimum planting distance is around 20 centimeters.
Location and soil
Thai basil needs a sunny and warm location protected from rain and wind. It can also be planted in a bed, but cultivation in a container is easier. The soil should be nutrient-rich, well-drained, humus-rich, and sufficiently moist. Waterlogging should be avoided at all costs.
Tomatoes, cucumbers, and zucchini make good bed neighbors. Bad neighbors include other labiates such as lemon balm, sage, and thyme.
Varieties
- Thai basil ‘Siam Queen’ is an award-winning variety with a peppery aniseed aroma. It has dark green leaves and purple flowers that appear from June.
- Thai basil ‘Chang’ is a sweet and aromatic variety with glossy, rich green leaves, red stems, and purple-pink flowers.
Thai basil care
Thai basil is relatively easy to care for. Find out below what you can do to keep the plant vital and productive for as long as possible.
Watering
The soil should never dry out completely, as Thai basil loves slightly moist soil throughout. However, you should not overdo it with watering, as permanently wet soil is not good for the plant.
Fertilization
Unlike most other herbs, Thai basil is quite hungry for nutrients. If it is given a slow-release fertilizer or compost when it is planted, it will not need much more during the season.
Potted plants mainly require further fertilization with slow-release fertilizer, compost, or multiple but less concentrated fertilizers. If the plant is grown in a bed, it can usually manage without additional fertilization.
Pruning
Thai basil should be pruned or harvested as regularly as possible. You can find out what to look out for when pruning in the “Harvesting” section below.
Propagation
If you want to propagate the plant, you can do this by sowing or using cuttings. The basil seeds are collected shortly before the first frost and stored until sowing the following spring. You can find out what to look out for when sowing in the section “Sowing and planting Thai basil” above.
To propagate cuttings, use shoots that are around ten centimeters long and have not yet flowered. The lower half of the leaves are removed and placed in a glass of water. If the water is changed regularly, the shoots will root within a few days.
Overwintering
The spice plant is not hardy and should be brought indoors when temperatures fall below 12 degrees. It is best kept in a bright place at 15 to 18 degrees through the cold season. Even in its winter quarters, it needs to be watered regularly and occasionally given a little fertilizer.
Repotting
After overwintering, the plant should be repotted in a larger pot.
Toxicity
The plant is considered non-toxic. Nevertheless, it is recommended not to consume the herb in excess.
Alternatives
Basil ‘Black Thai’ is a columnar basil that can grow over a meter tall. The dark red leaves have the aniseed-like taste of Thai basil.
Bee friendliness
The flowers of Thai basil are a sought-after source of food for bees and other insects.
Diseases and pests
The plant is susceptible to various fungal diseases, especially in warm, humid summers. Infected shoots should be cut off immediately and then disposed of.
The most common pests that basil has to contend with are snails. Snail collars, for example, can prevent snails from attacking the plants. Coffee grounds, which are also a good fertilizer for Thai basil, can also deter snails.
Harvesting and storage
Thai basil can be harvested as soon as it has produced enough leaves that are strong and lush green. The biggest mistake when harvesting is to pluck individual leaves from the shoots. It is better to cut off the tips of the shoots above a pair of leaves that are not yet lignified.
The leaves taste best fresh. If you want to preserve them, you can simply freeze them.
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Use in the kitchen
The plant has a sweet licorice and aniseed-like flavor. It is mainly used in curries, soups, and sauces and is only added shortly before the end of the cooking time. Thai basil should not be cooked with the dish as it loses its aroma very quickly. It can also be used raw, for example, in salads.