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. Grafting your own or buying grafted plants is another way to raise tomatoes.
Sow seed in late March to early April for outdoor crops, and in mid March 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.
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
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.