Grow tomatoes in pots on a sunny patio

Why a sunny patio is perfect for tomatoes

Tomatoes are sun-worshippers, and in the UK the warmest, most sheltered spot in the garden is often a paved patio against a south-facing wall. That trapped heat and reflected light is exactly what these plants crave, and it ripens fruit a good fortnight earlier than an exposed veg patch. Growing in pots also gives you complete control over the compost, so you can sidestep the soil-borne problems that plague open-ground growing.

The trick is choosing the right varieties. Forget the tall cordon types that need staking, tying and endless side-shoot removal. On a patio you want bush, also called determinate, varieties. They stay compact, produce a heavy crop in one generous flush, and need almost no pruning. Look for 'Tumbling Tom' in red or yellow for hanging baskets, 'Maskotka' and 'Garden Pearl' for cherry-sized fruit, 'Red Alert' for early ripening, and 'Totem' or 'Roma' if you fancy a paste tomato for sauces. All of these will happily crop in a 10 to 15 litre pot on a patio.

Pots, compost and the right spot

Size matters more than you might think. A tomato's roots want room to roam, and cramped roots mean small fruit and constant watering. One plant per pot, and a pot of at least 10 litres for cherries and 15 to 20 litres for larger bush types. Terracotta looks lovely but dries out fast, so glazed ceramic, plastic or fabric grow bags are more forgiving. Whatever you choose, it must have drainage holes at the bottom.

Use a peat-free multipurpose compost with added John Innes, or mix your own with a couple of handfuls of garden compost and a slow-release fertiliser. Add a handful of perlite or grit for drainage. Never use old compost from last year's pots — it will have lost its structure and may harbour disease.

Position your pots somewhere that gets at least six hours of direct sun a day, ideally against a wall that soaks up heat. A bit of shelter from strong wind helps too, since tall plants in pots can topple. If your only option is a slightly shaded corner, lean towards cherry varieties, which cope with less light than the beefsteaks.

Planting up and supporting

Sow seed indoors in late February or March, or buy young plants from a garden centre in May if you would rather skip the windowsill stage. Harden plants off for a week before moving them outside, and wait until the risk of frost has passed — usually the end of May in the south, early June further north.

When planting, bury the stem up to the first set of leaves. Tomatoes will grow roots along that buried stem, giving you a sturdier plant. Water the pot thoroughly before and after planting, and leave a 2cm gap between the compost surface and the rim so you can water without it running straight off.

• Push a sturdy cane or a ring of three canes into the pot for support, even on bush types.
• Mulch the surface with gravel, bark or even torn-up newspaper to slow evaporation.
• Space pots at least 30cm apart so air moves freely between them.

Watering and feeding for a generous crop

Irregular watering is the number one reason patio tomatoes disappoint. When the compost dries out and then floods, the fruit splits and the plant struggles to take up calcium, which causes the black sunken patch of blossom end rot. Aim for consistently moist, never sodden. In hot weather that can mean watering twice a day, morning and early evening, checking by pushing a finger into the top few centimetres of compost.

Feeding is just as important. From the moment the first tiny green tomatoes appear, switch to a high-potash tomato feed and apply it once a week, following the dilution on the bottle. Before that, the slow-release fertiliser in the compost is plenty. Overfeeding with a general-purpose feed gives you masses of leafy growth and very little fruit, so resist the urge to be generous.

A few practical habits make a real difference:

• Water in the morning where possible, so foliage dries before evening and blight has less chance to take hold.
• Feed after watering, never onto dry compost, which can scorch roots.
• In very hot spells, stand pots in a shallow tray of water for half an hour to let them drink their fill.

Pinching, pests and small problems

Bush varieties need very little intervention. You may remove the odd side shoot to keep the plant open, and pinch out the growing tip once four or five trusses have set fruit, which directs energy into ripening rather than more leaves. Remove any yellowing lower leaves to improve airflow.

Watch for greenfly and whitefly, particularly in still, humid weather. A strong jet of water from a spray bottle dislodges them, and planting a few marigolds or basil alongside your pots encourages natural predators. Outdoor tomatoes in the UK are far less troubled by blight than those in a damp greenhouse, but if you spot brown patches spreading on leaves, remove affected foliage immediately and keep the plants well ventilated.

Harvesting and making the most of the season

Pick fruit when it is fully coloured and gives slightly to a gentle squeeze — flavour develops on the plant, not on the kitchen windowsill. Cherry types ripen in waves from midsummer, and regular picking encourages more to set. If the weather turns cool and wet in September, bring any remaining green tomatoes indoors and ripen them on a sunny sill next to a ripe banana, or turn them into chutney.

At the end of the season, tip spent compost onto the flower beds or into the compost bin rather than reusing it, and clean your pots ready for next year. With two or three well-chosen bush plants on a warm patio, you can reasonably expect a couple of kilos of tomatoes from a space no bigger than a doormat — and there are few pleasures in a small garden quite like picking your own for a summer salad.