Why a balcony is a brilliant growing space

Even the smallest balcony can produce a surprising amount of food. A couple of metres of railing, a sunny corner, and a few well-chosen pots are enough to keep you in salad leaves from May to October, with tomatoes, herbs and chillies thrown in for good measure. The trick is to work with the space you have rather than fighting it, and to choose plants that actually enjoy growing in containers.

Balconies have their own microclimate. They are often warmer than the garden below, sheltered from frost by the building, and they drain quickly because air moves around the pots. That is good news for heat-lovers like tomatoes, basil and chillies, and it means you can start earlier in spring than you might expect. Get the basics right and a balcony becomes one of the most productive little plots in the house.

Choose compact crops that earn their place

Space is precious, so every pot should be pulling its weight. Trailing and dwarf varieties are your friends here, because they crop heavily without needing height or a huge root run.

• Tomatoes: look for bush or tumbler types rather than tall cordon varieties. A single plant in a 10-litre pot will happily trail over the edge of a railing planter.
• Salad leaves: loose-leaf lettuce, rocket and mizuna are cut-and-come-again crops. Sow a pinch every fortnight and you will never be short of a sandwich filling.
• Radishes: ready in as little as four weeks, which makes them perfect for filling gaps between slower crops.
• Chard and spinach: the colourful stems of rainbow chard look wonderful in a pot and you can harvest outer leaves for months.
• Herbs: basil, parsley, mint and chives all thrive in containers and cost far less than supermarket bunches.
• Chillies and dwarf French beans: compact, handsome plants that crop generously in a warm, sheltered spot.

Avoid maincrop potatoes, sweetcorn, brassicas and anything described as a large pumpkin. They need space and time you simply do not have on a balcony.

Pick containers that do some of the work for you

Self-watering containers are the single best investment for a balcony garden. They hold a reservoir of water at the base, which the compost draws up through a wick, so plants stay evenly moist for days rather than hours. This matters enormously in summer, when a terracotta pot in full sun can dry out by mid-morning.

If you would rather use what you have, any container will do provided it is big enough and has drainage holes. As a rough guide, aim for at least 10 litres per tomato plant, 5 litres for a lettuce or chilli, and 3 litres for herbs. Line terracotta with a plastic inner pot if you want to slow evaporation, and always use saucers or pot feet so drips do not annoy the neighbours below. Bear in mind that wet compost is heavy, and check your balcony's weight limits if you plan to go large.

Position pots to catch the best light

Most vegetables want six hours of direct sun a day, but few balconies offer that everywhere. Spend a day watching where the light falls: a south-facing balcony will be bright from morning to evening, an east-facing one gets gentle morning sun, and a west-facing one comes into its own in the late afternoon. North-facing balconies still work, but stick to leafy crops like lettuce, spinach and mint.

Put your sun-hungry tomatoes, chillies and basil in the brightest spot, and rotate pots every week or two so plants do not lean permanently towards the light. Railing planters are ideal for trailing tomatoes and strawberries, while a small tiered shelf lifts pots up where low walls or railings cast shade. In high summer, a little dappled shade during the fiercest afternoon sun actually helps lettuce and spinach from bolting.

Watering, feeding and coping with wind

Balcony plants dry out fast, so water in the morning when you can, and check self-watering reservoirs every couple of days in hot spells. Rain rarely reaches pots tucked under an overhang, so do not rely on the weather.

Container compost runs out of nutrients quickly. Start with a good peat-free multipurpose compost, then feed tomatoes, chillies and beans with a liquid tomato feed every week or two once flowers appear. Leafy crops need less — a dilute general feed every fortnight is plenty.

Wind is the quiet killer. It snaps stems, dries leaves and topples pots. Fix a lightweight windbreak of bamboo screening or fine netting to the railing, secure tall plants with a cane, and choose heavier pots over featherweight ones.

A simple rhythm to keep it going

Start sowing hardy salad leaves and radishes from March, and hold off on tomatoes and basil until late May, once nights are reliably warm. Keep sowing little and often rather than all at once, and you will have a steady supply instead of a glut followed by nothing.

Refresh spent compost by mixing in a little new material and a handful of slow-release feed, and reuse it for leafy crops. Growing your own on a balcony cuts food miles, plastic packaging and grocery bills all at once — and it turns a plain stretch of concrete into somewhere you will genuinely want to sit with a cup of tea.