Basil

Ocimum basilicum

Basil lives for one summer and can't stand cold. Its scented leaves last from early summer until the first cold nights. Pinch out the tips of the shoots and the plant stays bushy and leafy. It grows well in a pot in a warm, sunny spot out of the wind.

Looking after it

Water: Normal watering is right for basil. Keep the soil evenly moist. Water in the morning, at the foot of the plant rather than over the leaves. It hates having wet roots overnight. In hot weather a pot may need water every day. Feeding: It needs very little feeding. In the ground, give it none at all. In a pot, give a balanced liquid feed every few weeks in summer. Don't use tomato feed, because it pushes basil into flower.

Picking and keeping

Pick the shoot tips just above a pair of leaves, a few from each plant. New side shoots then grow from there. Pinch out flower buds as soon as they appear, so the leaves stay tender. In the fridge, basil turns black. Stand the stems in a glass of water at room temperature instead and it keeps for a few days. For longer, freeze the chopped leaves in oil or make pesto.

What can go wrong

Downy mildew. The leaves turn yellow between the veins, with a grey-purple fuzz underneath, mostly in humid weather. Water the soil in the morning and give plants room. Pull out any plants that have it.
Cold damage. The leaves turn black and limp after cold nights. Keep basil indoors until the nights stay warm. As autumn cools, bring pots in or cover the plants.
Slugs and snails. They can eat young plants overnight. Grow basil in pots, then check after dark and pick them off.

Growing facts: RHS, UC ANR and seed-company sowing guides. Basil care: RHS. pH: Clemson and University of Connecticut extension.