Sow your tomato seeds in March or April, approximately 6-8 weeks before the final frost of the winter, or earlier if you're growing your tomatoes in a greenhouse. Sprinkle the seed thinly onto good quality seed compost.
Cover with 1.5mm of compost and water lightly with a fine-rose watering can.
If you're only growing a few plants, sow two seeds into a 7.5cm (3") pot. Keep the compost moist, but be careful not to over-water as wet conditions can encourage "damping-off" disease, and other mould problems. At a temperature of 21 degrees celsius, tomato seeds usually germinate in 7 to 14 days. After germination remove the smaller plant.
Pot on the tomato seedlings as soon as they're big enough to handle. Hold the plants by the leaves, taking care not to touch the stems, and transplant them into 7.5cm (3in) pots. Protect the plants from frost, cold winds, and draughts which might kill them.
Tomato plants need a lot of water and feed if they're to produce a bountiful crop. For best results, water little and often. Some gardeners leave a few filled watering cans to warm in their greenhouse so the water is not shockingly cold from the tap or water butt.