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Dec 13, 2023

How to grow tomatoes: When to plant them, how long they take to grow and the best varieties for the UK

Sow tomato seeds in a heated propagator in late winter for planting in April in

Sow tomato seeds in a heated propagator in late winter for planting in April in a greenhouse, or sow in early spring where they are to be planted outdoors once the risk of frost has passed. Seedlings are placed one per small pot and allowed to grow – ideally well-spaced so their leaves never touch to get sturdy plants.

Growing good tomato transplants is difficult without a heated greenhouse, although sunny windowsills can be used. Many gardeners prefer to buy young plants from garden centres and nurseries from mid-spring. Delay planting out until the first yellow flowers are seen – if planted before there tends to be excessive leaf at the expense of flowers and fruit.

Tomatoes need plenty of sunlight and fertile soil. Enrich soil with a bucketful of compost every square metre or a moderate dressing of general fertiliser before planting. Many, perhaps most, tomatoes are grown in growbags, but these dry out fast and large (20l) pots filled with growbag compost are easier to manage.

Bush tomatoes, ‘Red Alert’ and ‘Romello’ for example, fruit at the end of each stem, and except for a short stake to hold the central stem upright, need no support. The best quality fruits however come from cordon varieties such as ‘Shirley’ and ‘Ailsa Craig’, which when grown outdoors, are tied at intervals to a 1.2m stake with side shoots removed and then trained up the stake until four trusses of flowers have formed after which the growing tip at the top of the plant is pinched out or ‘stopped’ and the crop allowed to ripen. Greenhouse tomatoes can be allowed to grow up a string attached to the roof or a longer cane and six trusses allowed to form before stopping. Extra trusses tend not to ripen.

Potassium is needed in large quantities for tomatoes to ripen and it is worthwhile applying a potassium rich tomato fertiliser every week from when the fruits are full size and ready to ripen.

Blight disease is a menace outdoors in late summer if it turns rainy but blight resistant varieties such as ‘Crimson Crush’ or ‘Burlesque’ give fair protection.