Native to tropical Africa and Asia, sweet basil arrived in European herb gardens centuries ago and never left. It grows quickly from seed or transplant once frost is firmly behind you, reaching 4 inches to 3 feet depending on the cultivar, with soft, aromatic leaves that perfume everything around them on a warm afternoon.

Pinch the stem tips regularly and remove flower buds as soon as they form — this keeps the plant producing the tender, flavorful foliage rather than going to seed. Purple-leaved cultivars like 'Rutgers Obsession' hold their color well in the heat and pull double duty as ornamentals; try them at the front of a sunny border or paired with silver herbs in a container. Fusarium wilt and downy mildew are the real threats; seek out resistant cultivars if either has been a problem in your garden before.