March is the ideal time to start sowing tomatoes if you intend to grow from seed, or for buying plug plants for growing on. Tomatoes are not hardy and will need to be kept under glass in a warm place until later in the year for planting out late May.
If you are new to growing tomatoes, or just need a bit of advice, the sunday gardener has a step by step guide starting with How to grow tomatoes covering all the tomato growing steps, including potting on, pinching out side shoots and the all important watering and feeding regime.
Check out The Sunday Gardener's easy paperback guide " Success with Tomatoes"
Lots of video advice about growing tomatoes on the Sunday Gardener You Tube channel .