Why a balcony is a brilliant place to grow food

Even a modest balcony can supply pickings for months. The key is light. Most fruiting crops — tomatoes, strawberries, peppers — need at least six hours of direct sun a day, so a south or west-facing railing is prime territory. East-facing spots are gentler and suit salad leaves and herbs, which can bolt or scorch in fierce afternoon heat. A north-facing balcony is not hopeless either; leafy crops such as rocket, spinach, parsley and mint will manage in bright shade, just more slowly.

Wind is the other consideration. Tall buildings funnel it, drying compost and snapping stems. Grouping pots together, fixing them low and using a screen or trellis of climbing nasturtiums will calm things considerably.

Pots, compost and getting the basics right

Size matters more than style. Small pots dry out fast and restrict roots, so choose the biggest containers your space will take.

• Salad leaves and herbs: 15–20cm deep, ideally a wide trough for cutting.
• Tomatoes: 30–40cm per plant, or a grow bag with three plants.
• Strawberries: 20–25cm deep, with three or four plants in a 30cm pot.
• Mint and other spreaders: always their own pot, or they will take over.

Every container needs drainage holes and a layer of broken crocks or gravel at the base; a saucer underneath protects the neighbours below and holds a little water in summer. Always use good-quality peat-free compost. Peat-free blends dry out a touch faster than the old peat-based types, so mix in some home-made compost or worm compost for body, or a handful of water-retaining granules, and top-dress with a gravel mulch to slow evaporation. A loam-based compost is worth the extra for permanent herbs such as rosemary and thyme.

Fast crops: salads and herbs

Nothing rewards a small space like cut-and-come-again leaves. Sow rocket, mizuna, mustard, spinach and loose-leaf lettuces thinly in a trough, cover lightly, and start cutting when leaves are 5–8cm tall. Take the outer leaves and the plant keeps producing. Sow a fresh pinch every three weeks from March to August for a continuous supply.

Herbs are generous, too. Basil needs warmth and sun — sow after the last frost and pinch out the tips to keep it bushy. Flat-leaf parsley and chives crop for months in part shade and often survive winter. Thyme, oregano and rosemary prefer a grittier, leaner mix and less water than the rest. Coriander sulks and bolts in high summer, so sow it in spring and again in late August.

Tomatoes and strawberries in containers

Tomatoes are the classic balcony crop. Choose a cordon variety for a large pot and pinch out the side shoots, or a bush type for a hanging basket or smaller container. Plant one per 30cm pot, burying the stem deeper than it was in its original pot to encourage roots, and tie the growing stem to a sturdy cane. Water evenly — irregular watering causes split skins and blossom end rot — and never let the compost dry right out.

Strawberries work beautifully in pots and planters, and three or four plants will crop for two or three years before they need replacing. Alpine and wild strawberries are easy from seed and give small, intensely flavoured fruits over a long season. Tuck straw or a piece of matting under the berries to keep them clean and lift them away from slugs, and peg down runners into small pots of compost to make free new plants.

Watering, feeding and keeping plants healthy

From June onwards, expect to water daily, and twice on hot, breezy days — containers simply have no reserve. Water in the morning if you can, so foliage dries before evening. Rainwater collected in a butt or lidded container is better for plants than tap water, and far better for the environment.

Feeding is what separates a tired balcony from a productive one. Compost nutrients run out after roughly six weeks of watering and cropping.

• Leafy crops and herbs: a general-purpose liquid feed every fortnight.
• Tomatoes, peppers and strawberries: a high-potash tomato feed every week once flowers set fruit.
• Autumn: stop feeding and let plants wind down naturally.

Pests will find you, but rarely in numbers that demand drastic action. Blast aphids off with a jet of water, pick off caterpillars by hand, and grow flowers among the edibles — calendula, nasturtium, borage and chives all bring in hoverflies and ladybirds that do the work for you. It looks better, too.

Small changes, genuinely sustainable

Container growing is already a low-impact way to eat, but a few habits make it more so. Reuse what you have — yoghurt pots for seedlings, old tins and crates lined and drilled for herbs, fabric bags for tomatoes. Make your own compost in a sealed bin, or keep a wormery for kitchen scraps, which cuts waste and feeds your pots for free. Collect rainwater, avoid peat, and sow pollinator-friendly flowers alongside the vegetables.

Come autumn, most pots can stay outside if they are raised on feet to prevent waterlogging and moved against a sheltered wall. Chard, winter lettuce, corn salad and land cress sown under a cheap cloche or on a bright windowsill keep the harvest going through the dark months — and by February you will be itching to sow again.