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Tomatoes

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last updated Feb 27, 2014
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Tomato 'Costoluto Fiorentino' (beefsteak). Credit:Tim Sandall/RHS The Garden.

Tomatoes produce abundant delicious fruits in a range of colours, shapes and sizes. They are easily grown in gardens, greenhouses or containers and are appreciated by children and adults alike.

Sowing seed Back to top

Tomatoes are very easy to grow from seed. Alternatively you can buy tomato plants from late spring from garden centres and are a good option where you can't maintain the right conditions for germination and growing on.

Sow seed in early spring for outdoor crops, and late winter for growing in an unheated glasshouse. Seed can be expensive, but usually only a few plants are needed, and germination is usually good.

  • Fill 9cm (3½in) pot with seed or multipurpose compost
  • Level and firm the compost, then water
  • Sow seeds on the compost surface, spacing them evenly, about a finger-width apart, to prevent damping off disease
  • Cover the seed with a layer of vermiculite
  • Keep at approximately 21°C (70°F), ideally in a heated propagator, until seedlings emerge
  • Transfer seedlings to a heated greenhouse or, although less good, a sunny windowsill

Seedlings emerge after about five days. Place them in the best-possible light (such as a greenhouse) and at a temperature of around 18°C (65°F) to prevent seedlings becoming long, thin and ‘leggy’. Leggy plants produce their first flowers high up on the plant leading to a bare, unproductive lower stem.

Pricking out

Seedlings should be large enough to prick out into separate pots of multipurpose compost two weeks or so after sowing:

  • Ideally, fill pots two days before pricking out, water well, and allow to warm up to room temperature to reduce the chance of the seedlings damping off
  • Hold seedlings by their cotyledons (seed leaves) to avoid damage to the delicate stems
  • Make a hole in the compost big enough to take the roots and lightly firm the seedling in place
  • Water in with tepid water
  • Reduce the temperature to 16ºC (60ºF) when plants reach 15cm (6in) high

Growing on

Ideally, grow on in a glasshouse (or failing this, a well-lit windowsill), spacing plants so that their leaves never touch to avoid legginess. About a month after pricking out, the plants will be ready for planting into their final positions – this is indicated by the first flowers showing their yellow colour. The stress of being grown in the confines of a pot promotes flowers earlier than in less stressful positions, such as growing in the ground.

Cultivation notes Back to top

Whether you raise plants from seed or buy your plants, they can all be grown in the same way.

Planting

Plant outside in early summer. In unheated greenhouses, planting can take place in mid-spring. Set plants 40cm (16in) apart and water in well.

Watering and feeding

Roots should be kept moist but never waterlogged. Pots and grow-bags require frequent watering.

Feeding isn’t essential for soil-grown plants, but those in bags or pots benefit from regular feeding, using tomato feed and following manufacturer’s instructions.

Fruit set

Tomato flowers self-pollinate readily. However, indoor plants benefit from being gently shaken to dislodge the pollen. Misting flowers with water can help fruit set.

Harvesting

Pick fruits as required, with the calyx (stalk) still attached. When cropping slows in early autumn, green fruits can be gathered and kept in a warm, dark place to ripen.

Pruning and training Back to top

Pruning and training depends on how your tomato cultivar naturally grows. The two main growth habits are: indeterminate (also called vine or cordon) or determinate (bush) tomatoes. When you buy seed or plants, check on the label to see what growth habit the plant will be.

Indeterminate (vine or cordon) tomatoes

  • Usually trained as a cordon – one central stem supported by a cane or string. Left untrained, they produce unproductive vegetation
  • Pinch out the laterals (sideshoots) that appear between the leaf and main stem
  • Remove the tip of the main stem two leaves above the fourth truss of fruits (for outdoor plants) or the sixth truss (for indoor plants), as subsequent fruits usually fail to ripen
  • Leaves below the lowest truss still bearing fruit can be removed to help control disease. However, de-leafing is best avoided
  • Flowers and fruit are borne on trusses (stalks bearing many flowers) that grow directly from the main stem

Determinate (bush) tomatoes

  • Tie plants loosely to a 1m (3ft) cane
  • Don’t remove side shoots as this will reduce cropping
  • Bush tomatoes produce compact plants with numerous short, sideshoots that terminate in a cluster of flowers

Other growth habits

Some tomatoes, especially beefsteak types, have a habit between that of an indeterminate (vine or cordon) and a determinate (bush) type. They produce vigorous lateral shoots that often terminate in a flowering truss and, so, these are not usually removed, except to curb unruly growth. Be careful when pinching out these shoots that you preserve laterals, which will flower and bear fruit.

Cultivar Selection Back to top

There are hundreds of tomato cultivars available, these are just some of our favourites:

‘Ferline’: This is a beefsteak tomato with flavoursome, large red fruits and some resistance to tomato/potato blight. An indeterminate (vine or cordon) type.
‘Gardener’s Delight’ AGM: For small, flavoursome tomatoes, try this reliable and heavy cropping cultivar.
‘Tornado’ AGM: This determinate (bush) cultivar is hard to beat outdoors.
‘Tumbler’: A trailing tomato that can be grown in hanging baskets. A small determinate (bush) cultivar.

Links

RHS AGM Vegetables - list of all vegetables awarded the AGM (Adobe Acrobat pdf)
Article from The Garden magazine, August 2007: Tomato taste test
RHS trial results: Cherry and cherry-plum tomatoes, 2007 (Adobe Acrobat pdf)
RHS trial results: Beefsteak tomatoes, 2003 (Adobe Acrobat pdf)

Problems Back to top

In a warm summer, tomatoes are easy to grow if they are well watered. However, problems can occur, with fruit ripening, fruit splitting and cracking, leaf problems, stem problems, blossom end rot, tomato blight, tomato leaf mould and tomato viruses.

Quick facts

Common name Tomato
Latin name Solanum lycopersicum
Group Vegetable
Flowering time Summer
Planting time Spring to early summer
Height and spread Various
Aspect Sun or very light shade
Hardiness Tender
Difficulty Easy
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