Seedlings

Put them in the sun during the day and bring them in at night until all danger of frost has passed. Check out the estimated last frost date in your area.

Tomatoes like lots of light and a constant mild temperature.
They hate cold, windy, wet weather (a bit like an English summer ... just joking!), too much watering and poor light levels. As the plants grow transplant them into bigger pots.

Some gardeners use grow lights to supplement the daylight hours or extend them. This is a good idea if you want to sow early and have tomatoes early, but it can be a bit expensive in energy bills.

Sowing Seeds

Sow a few seeds in a small pot (3.5 inch) just below surface 1/8 inch deep. Place pot in a saucer of water for a minute or two and cover with cling film. Use seed compost because it holds more moisture and is best for the fine roots of seedlings.

Keep in a warm place (18-21C) and as soon as the seedlings appear, put them in a light position (not too warm, around 16-18C) to stop them from becoming too leggy.

After their first true leaves are growing, transplant the seedlings into individual small pots so that the seed leaves are just above the soil level.

Use potting compost because it contains the mixture and nutrients suitable for young plants. It’s also a good idea to add a little of the seed compost to the transplant mixture as this will help the roots become established.