Why a sunny balcony is a brilliant spot for tomatoes

Tomatoes are Mediterranean plants at heart, and a balcony gives them much of what they crave: shelter, warmth and reflected light. A south-facing wall bounces heat back onto the plants and holds it overnight, which keeps growth steady and helps fruit colour up properly. Aim for at least six hours of direct sunshine a day. East-facing spots can work on the strength of morning sun, but south and west are reliably better.

Wind is the quiet enemy of container growing. It dries compost within hours, snaps brittle stems and keeps pollinating insects away. Tuck pots into a corner, behind a railing, or screen them with bamboo roll if your balcony is exposed. Just as important, leave a gap between pot and wall so air can move around the foliage — good airflow is one of the simplest ways to keep disease at bay.

Choose compact varieties for pots

Not every tomato suits container life. Tall cordon varieties will grow, but they need staking, tying and regular pinching. Bush and trailing types are far more forgiving, especially if you are new to this.

• Tumbling Tom — a trailing cherry type that spills happily from a railing pot or hanging basket.
• Gardeners' Delight — a classic cordon cherry, sweet and generous, perfectly happy in a 15-litre pot with a cane.
• Losetto or Crimson Crush — blight-resistant choices, worth having if your summer turns damp.
• Shirley — a dependable medium-sized cordon for a sheltered, sunny corner.
• Marmande — big, beefsteak flavour, but give it the largest pot you can find and feed it well.

Raising plants from seed gives you the widest choice; sow indoors in late February or March in a warm, bright spot. If you would rather skip that stage, young plants appear in garden centres from late April. Whichever route you take, read the label for the words determinate (bush) or indeterminate (cordon), because it changes how you look after them.

Containers, compost and drainage

Size matters more than anything else. A tomato crammed into a tiny pot will dry out constantly, suffer blossom end rot and reward you with a handful of fruit. Give each plant a container of at least 10 to 15 litres, and go bigger if space allows — 20 to 30 litres is not excessive for a beefsteak. Depth is the measurement that counts, so a deep pot beats a wide shallow one every time.

Use a peat-free multipurpose compost and fork through a couple of handfuls of garden compost or well-rotted manure for body and moisture retention. Drainage is non-negotiable: check for holes, add a layer of grit or broken crocks at the base, and stand pots on feet or bricks so surplus water can escape freely. Terracotta dries out faster than plastic, while a light-coloured plastic pot keeps roots cooler on a scorching afternoon.

Planting out and giving support

Wait until the risk of frost has passed — usually mid to late May across most of the UK, and a week or two later in the north. Harden young plants off over a week or so by moving them outside for a few hours each day before leaving them out permanently.

Plant deeply. Bury the stem up to the first set of leaves, having removed those leaves first. Tomatoes produce roots along the buried stem, and that extra root run makes a noticeably stronger plant. Water thoroughly after planting and keep the compost evenly moist for the first fortnight.

Cordons need a cane or a sturdy string support, tied with soft twine in a loose figure-of-eight so the stem is never pinched. Bush varieties need little more than a short stick, and trailing types can simply be left to spill over the side of their pot.

Watering and feeding: the routine that makes the difference

Irregular watering is the number one cause of split fruit and leathery brown patches at the base of tomatoes. Little and often is the rule. On a hot balcony, a fruiting plant may need water twice a day. Check by pushing a finger a couple of centimetres into the compost; if it feels dry, water until it runs from the base.

Water in the morning where you can, straight onto the compost rather than over the leaves, and keep foliage dry to reduce disease risk. A saucer beneath the pot helps in a heatwave, but empty it if it stays full for long, as soggy roots invite trouble.

Begin feeding with a high-potash tomato fertiliser once the first truss of flowers has set small fruits. Feed weekly at the strength on the bottle, and continue through the season. In late summer, when you want the remaining fruit to colour and flavour up, ease off the feed and let the compost dry slightly between waterings — that gentle stress concentrates flavour wonderfully.

Pinching, ripening and the harvest

On cordon tomatoes, pinch out the side shoots that appear in the join between leaf and main stem — the plant's armpits. Left alone, they turn your neat plant into a leafy tangle with far fewer tomatoes. Once five or six trusses have set, pinch out the growing tip to stop it stretching upwards and to push energy into swelling fruit.

Remove a few of the lowest leaves as the season goes on. It improves airflow, lets light reach ripening trusses and makes watering easier. In a wet August, blight can sweep through outdoor tomatoes quickly, which is where those resistant varieties earn their keep.

Fruit is ready when it is fully coloured and pulls away with a gentle twist. Taste one before you pick the lot — flavour is at its peak in the first day or two after full colour. At the end of the season, any green tomatoes can be ripened indoors on a sunny windowsill beside a ripe banana, or cooked down into chutney. Either way, nothing from a balcony pot tastes quite like it.