Holy Basil (Ocimum tenuiflorum or Ocimum sanctum) also called tulsi. It contains a high level of the essential oil eugenol and it has been used in Ayurveda for a very long time. Native to India and it is widely cultivated in South East Asia. Also widely used in Thai cuisine.
Sow the holy basil from February onwards inside or outside from May, in small pots, or in fine seedbed.
Just cover the seeds with fine compost/soil, can be grown inside all year round, germination 10-15 days, keep the soil slightly moist, do not overwater. Basil needs a temperature of 18 Celsius and above to germinate successfully.
Transplant outside in June, to a sunny/partly shady position. Plants like slightly dry conditions and the concentration of the essential oils will be higher. More on growing basil.
Keep picking the leaves to encourage further production.
Pick the leaves just before flowering if you want to dry and keep them. To preserve the full flavour of the leaves the best is to freeze the leaves or chop the leaves and mix with water then make ice cubes with the mixture.