Basil - Thai Basil can be sown indoors all year round. For outdoor cultivation, sow indoors from March to July and move outdoors as soon as temperatures exceed 20°C. Thai basil has narrow leaves with red stems and lilac-coloured flowers. This type of basil looks very nice in the ornamental garden or border. Thai basil has a subtle liquorice/aniseed taste to it with a hint of pepper.