Why herbs belong by the back door

A pot of basil on a sunny windowsill, or a row of thyme and parsley on the doorstep, saves more trips to the shops than almost anything else you can grow. Supermarket herb packs are expensive and past their best. Keeping plants within a few steps of the kitchen means you actually use them: mint in new potatoes, parsley over a salad, basil torn over tomatoes. In the UK, fresh pickings run from April to October, and with a little planning some herbs will keep going much longer.

Pots, compost and drainage

Herbs in containers live or die by drainage. One hole in the base is not enough; look for several, or drill extra. Terracotta dries out fast, which suits thyme and oregano but means more watering. Basil and mint prefer more moisture, so plastic or glazed pots suit them better.

Size matters. A 20–25cm pot (5–7 litres of compost) is the minimum for a single strong parsley, basil or mint plant. Thyme copes in 15cm, but dries out quickly in a heatwave. Use fresh, peat-free multipurpose compost; old compost can carry vine weevil and root disease. Add crocks or gravel to the bottom, then fill to within 2cm of the rim so there is room to water.

Four reliable herbs for pots

These four earn their place on any doorstep. Each has its quirks, but none is difficult.

• Basil: sow in late spring, or split a supermarket pot into three or four smaller pots. It hates cold and wet. Keep it in the sunniest, most sheltered spot, water from below where possible, and pinch out growing tips to stop it flowering — once flower buds appear, leaves turn bitter.
• Parsley: flat-leaved parsley is the most useful. Soak seeds overnight before sowing, as germination is slow. It tolerates light shade, making it ideal for a north-facing windowsill. Cut outer stems at the base rather than snipping the top. It runs to seed in its second year, so sow fresh each spring.
• Mint: keep mint in its own pot, always — in shared containers it smothers everything else. Spearmint is best for cooking. Water generously and cut it hard when tired; it bounces back with tender leaves. Full sun gives the strongest flavour.
• Thyme: common and lemon thyme are the most useful. They need full sun and sharp drainage. Mix multipurpose compost with an equal part of horticultural grit. Water sparingly — overwatering is the usual reason thyme dies in a pot. Trim after flowering to keep it bushy.

Watering, feeding and British weather

Containers dry out far faster than garden soil. In a warm spell, basil in full sun may need watering twice a day. Check by pushing a finger into the compost; if it is dry 2cm down, water until it runs from the drainage holes. Never leave pots standing in saucers of water, except mint, which tolerates it. From June to August, feed with liquid seaweed or tomato feed every two weeks. Basil, parsley and mint appreciate it; thyme needs very little, so dilute to half strength.

UK summers swing from drought to downpour. In wet weather, move pots under the eaves or onto a sheltered windowsill to prevent waterlogging, especially basil and thyme. In a heatwave, group pots to shade each other and reduce evaporation. If you are away, stand pots in a tray of water in a cool, shady spot for a few days — enough to carry most herbs through a weekend.

Pick often, and pick properly

The more you cut, the more herbs grow. Regular harvesting keeps plants bushy and delays flowering. For basil, cut a stem just above a pair of leaves; two new shoots grow from that point. For parsley and mint, take outer stems, leaving the centre to develop. Never strip a plant bare — take no more than a third at a time. Sow a second pot of basil in midsummer for a succession as the first tires. Thyme can be cut lightly all year, but leave woody stems alone; new growth comes from the soft tips.

Overwintering and next year's sowings

Thyme is fully hardy and survives winter in a pot, though it resents sitting wet. Raise the pot onto feet or bricks so water drains freely, and move it against a south-facing wall. Parsley is biennial and will flower and die in its second year, so sow fresh plants in late summer for winter pickings on a cool windowsill. Mint dies back to the compost, but the roots survive; keep the pot barely moist and it shoots again in spring. Basil is a tender annual and will not survive a UK winter unless kept in a warm, bright room. Most of us let it go and sow again in May. That is the rhythm of a kitchen herb garden — simple, generous, and always within arm's reach of the chopping board.