Why a patio pot makes a perfect salad patch

You do not need a vegetable patch to eat something you have grown yourself this summer. A few containers against a sunny wall will happily produce bowlfuls of loose-leaf lettuce, crisp radishes and the slender spring onions that lift a sandwich into something worth sitting down for. All three are shallow-rooted, quick to mature and generous in the picking, which makes them ideal for the smallest of spaces — a doorstep, a balcony, or the paving outside the kitchen door. You pick only what you need, minutes before eating, so nothing wilts in the fridge and nothing is wasted.

Containers that last — and tread lightly

Almost any sturdy container will do, provided it has drainage holes. A depth of 15-20cm is plenty for lettuce and spring onions; give radishes 20-25cm if you want well-formed roots rather than small, woody ones. Width matters more than depth with leafy crops, because you will be sowing little patches rather than single specimens.

Before buying anything new, look at what you already own. Old washing-up bowls, wooden crates lined with hessian, terracotta pots and sturdy buckets can all be drilled and pressed into service. Reusing what exists is the most sustainable choice in container growing, and it often looks better than a matched set. If you do buy, terracotta and untreated wood are breathable and last for years. Raise pots onto feet or broken tiles so water drains freely and there is less damp shelter underneath for slugs.

The right compost for crops you will eat

Use a peat-free multipurpose compost. Peat bogs are among our most effective carbon stores and home to rare plants and insects, and modern peat-free mixes perform just as well for salad once you get used to watering them a little more often.

Mix in a couple of handfuls of garden or worm compost. It holds moisture and feeds the soil life in the pot, so you water less in July. Avoid filling containers with garden soil alone: in a pot it compacts, drains badly and stifles roots. Salads are light feeders, so a fortnightly dose of diluted comfrey or tomato feed once you begin cutting is usually all they need.

What to sow, and how deep

Sow thinly and cover lightly — salad seed is small and needs only a centimetre or so of compost over it.

• Loose-leaf lettuce — 'Salad Bowl', 'Red Salad Bowl' or 'Lollo Rossa'. Scatter over the surface, cover with about 1cm of compost and firm gently. Space plants 15cm apart for full heads, or 5-8cm if you will cut them young. Germination takes 7-10 days.
• Radishes — 'Cherry Belle' or 'French Breakfast'. Sow in short rows about 2-3cm apart, 1cm deep, and thin to 5cm. Ready in as little as three to four weeks.
• Spring onions — 'White Lisbon' is the reliable classic. Sow 1cm deep in drills 10cm apart, thin to 2-3cm, and pull as needed from eight weeks. 'Ishikura' is worth trying for autumn sowings.

Keep the compost moist while seeds germinate, and shade pots on hot afternoons. Radishes sown in midsummer heat bolt and turn woody, so give them afternoon shade or wait for cooler weather.

Little and often: succession sowing

The secret of a long salad season is not one big sowing but several small ones. Rather than filling every pot in April, sow a fresh 30cm pot of lettuce every two to three weeks from March to September, with a pinch of radishes and a short row of spring onions alongside. That way something is always at the picking stage and nothing arrives all at once.

In midsummer, move pots to a spot with morning sun and afternoon shade. From late August, sow winter-hardy varieties and keep them under a cloche or against a warm wall to carry on cropping into the colder months.

Harvesting, watering and inviting the wildlife in

Water in the morning, aiming at the compost rather than the leaves, and use rainwater from a butt wherever you can. Damp foliage overnight invites mildew; dry compost invites bolting. Check pots daily in hot spells, as they dry out far faster than a border.

Harvest loose-leaf lettuce by taking the outer leaves and leaving the crown to regrow, or cut the whole plant 3cm above the base for a second flush. Pull radishes when they reach the size of a ten-pence piece; leave them longer and they turn pithy. Spring onions can be pulled as babies or left to thicken.

A few small choices will bring wildlife in:

• Let one or two lettuces run to flower. Their small yellow blooms are a magnet for hoverflies, whose larvae devour aphids.
• Keep a shallow dish of water with pebbles in it for bees.
• Skip slug pellets. Patrolling at dusk with a torch, or sinking a beer trap, deals with most problems and protects the ground beetles and thrushes working on your behalf.
• Spread spent compost on the borders at the end of the season rather than binning it — it is still full of life.

Start with one pot, one packet of seed and a sunny corner, and you will be eating your own leaves within a month.