Start by reading your balcony properly

Before you buy a single pot, spend a week watching how the light moves across your space. A south-facing balcony that catches six or more hours of direct summer sun will grow tomatoes, peppers, cucumbers and beans with real enthusiasm. East or west-facing spots, with four to six hours, suit salad leaves, herbs, chard, beetroot and most root crops. A north-facing balcony is the hardest brief, but it is not hopeless: think leafy greens, mint, parsley and rocket rather than anything that needs to ripen fruit.

Wind matters as much as sun. Even a third-floor balcony can funnel gusts that snap stems and dry compost out within hours. Notice whether your space is sheltered or exposed, and whether rain ever reaches the pots at all. Many balconies are effectively under a roof, which means every drop of water will come from your watering can.

Finally, check the practical limits. Weigh up how much load your balcony can take before you fill it with heavy containers, and keep the heaviest pots close to the wall or over a supporting beam rather than out at the edge. If you are unsure, ask your landlord, managing agent or a structural engineer. A 30-litre pot of damp compost can weigh well over 20kg, so it adds up quickly.

Plan the layout before you plant

Even a modest balcony, say 1.2 metres by 2 metres, gives you nearly two and a half square metres of growing space. That is enough for a genuine supply of cut-and-come-again leaves, herbs and a few fruiting crops if you plan it deliberately.

• Use height as well as floor space. A tiered shelving unit, a wall-mounted trough or a sturdy railing planter can double your usable area. Just remember that high pots dry out faster and are harder to reach with a can.
• Group by need. Put sun-lovers together in the brightest spot and shade-tolerant salad crops in the cooler corner. This makes watering and feeding far simpler.
• Leave a working gap. You need somewhere to stand, kneel and set down a trug. Aim for at least 60cm of clear floor.
• Keep a clear route to the tap. If you have to carry water through the flat, a small water butt or a lidded container on the balcony will save your back.

Crops worth their footprint

On a balcony, every pot has to earn its place. Prioritise crops that are expensive to buy, taste noticeably better home-grown, or keep producing over a long season.

• Salad leaves: cut-and-come-again mixes, rocket, mizuna and loose-leaf lettuce. Sow little and often for a near-continuous supply.
• Herbs: basil, parsley, coriander, chives, thyme and mint. Mint needs its own pot or it will invade everything else.
• Tomatoes: choose compact bush or determinate varieties for containers. A single plant in a 25–30 litre pot will crop heavily without needing tall supports.
• Dwarf French beans and mangetout: productive, attractive and far less fuss than climbing types. They also fix nitrogen in the compost.
• Chard and kale: pick outer leaves for months, and both tolerate a little shade and wind.
• Radishes, spring onions and beetroot: quick, compact and ideal for filling gaps between slower crops.
• Chillies, strawberries and new potatoes: the luxury items that taste best straight from the plant.

Pots, compost and drainage

Size really does matter. Small pots dry out, heat up and stunt plants, so go as large as your space and budget allow. A rough guide: salad and herbs in 5–10 litres, chard and beans in 10–15 litres, tomatoes, peppers and potatoes in 25–40 litres.

Terracotta looks lovely but dries out quickly; glazed ceramic holds moisture better; fabric grow bags are light and air-prune roots beautifully. Whatever you choose, it must have drainage holes. Add a 2–3cm layer of gravel or crocks at the base, then stand pots on feet or small blocks so water can escape freely rather than pooling under them.

Use a good peat-free multi-purpose compost, and mix in around 20 per cent perlite or coarse grit for drainage. For crops that will sit in the same pot all summer, a soil-based compost gives better structure and holds nutrients for longer. Top up with a mulch of compost or gravel to slow evaporation.

Watering, feeding and succession sowing

Balcony compost dries out fast, so check it daily in summer, ideally in the morning. Push a finger in to the second knuckle: if it feels dry, water until it runs from the base. Watering little and often is far better than a weekly deluge, and a self-watering container or a simple drip system takes the anxiety out of a weekend away.

Compost nutrients run out after roughly four to six weeks. From then on, feed weekly with a balanced liquid fertiliser, switching to a high-potash tomato feed once flowering begins. Crops in small pots need this more often than those in large ones.

Succession sowing is the secret to a steady harvest rather than a single glut. Sow a small tray of salad every two to three weeks from March to August, and re-sow gaps as soon as a crop finishes rather than leaving bare compost sitting idle.

Keeping plants healthy and cropping

Check plants twice a week, looking under leaves and at new growth. Aphids and whitefly are the usual culprits; a firm jet of water or a squirt of diluted washing-up liquid deals with light infestations. Fine mesh netting keeps cabbage white butterflies off brassicas and offers a little wind protection too.

In dry, hot spells, red spider mite can take hold, so mist foliage occasionally and keep plants well watered. Tomatoes and peppers benefit from a gentle tap of the stem at midday, or a quick tickle with a soft brush, to move pollen between flowers.

Pick regularly — the more you harvest, the more the plant produces. A few pots managed attentively will give you something fresh for most of the year, and there is real pleasure in stepping outside with a pair of scissors to gather dinner.