Native to dry scrub in Africa and Asia, basil requires a lot of heat to thrive, and can be prone to downy mildew. There are many varieties to choose from, however, some of which have been bred to withstand cooler conditions.

Basil 'Dark Opal' isn't one of the easiest basil varieties to grow, but its dark purple and slightly liquorice-flavoured leaves are worth a little extra effort. Sow seeds indoors in a greenhouse or on a warm windowsill, and don't move plants outside until summer. Water plants sparingly, ideally before noon so the roots have time to dry out before temperatures decrease in the evening. Harvest leaves regularly and remove flowers to concentrate the plant's energy on leaf production.