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The proper winter for many of us is hardly a timely reminder that we need to be sowing tomato seeds for an early summer crop. This only applies to tomato plants destined for greenhouse cultivation. The available window for sowing tomato seeds for greenhouse cultivation is January - March.

Tomato plants that are to spend the summer outdoors do not need to be sown this early, they will have to spend a lot longer indoors before the nights are warm enough for them to go outside, so seed germination is obviously best delayed; recommended for March and April. Sow them too early, and you end up with leggy, hungry plants crying out in early spring to be put outside into a larger pot or grow bags when it is still much too cold.

Tomato seeds are very easy to germinate, a good choice to involve children with, giving them the horticultural learning and hands-on brain stimulation that they just don't get with cbeebies. Tomato seeds also carry all the characteristics of the parent fruit (apart from the F1 hybrid types) so little fingers can also be involved with squeezing the seed out of the over-ripe fruits, drying out and storing in an envelope.

You can use the following step by step guide to sowing tomato seeds:

1. Fill enough pots or trays with a good quality seed compost. Give the compost a light watering
2. Scatter the seeds thinly on top of the compost approx. 2 - 3 cm apart
3. Cover the seeds with a thin layer of compost, (approx 1.5cm) ideally applied using an old kitchen sieve
4. Firm this compost gently with a small block of wood or the back of your hand
5. Keep just moist in a room with a temperature of between 15 - 20 °C
6. Seedlings will appear within two weeks

After the seedlings appear, the room temperature can be dropped to between 12 - 15 °C. It is important not to put them on a south facing windowsill where the temperature during the day shoots up and the excessive light levels cause excessive growth and possible leaf scorch.

When the young seedlings are 2 - 3 cm tall and relatively easy to handle they can be potted on into smaller pots and kept in the house. Gradually moving them from one room to another, each time with a small drop in temperature so that you are beginning to harden them off before they go out to the greenhouse.

When March and April arrive the young plants can be transplanted into large pots or grow bags in the greenhouse. The greenhouse should be heated, especially at night to protect against frost. The minimum greenhouse temperature must be maintained at 7 - 8 °C.

When you do plant the tomato plants in their final planting positions don't be tempted to cram too many into a small place. Tomatoes are very hungry plants, one plant in a grow bag will excel and produce almost as much fruit as 3 plants planted in the same grow bag.

When the time is right I will talk about cultivating tomatoes for growing outdoors. In the meantime, crack on now and sow those tomato seeds and you can look forward to plenty of greenhouse tomatoes in June

Some tomato varieties that you might like to consider planting are:

• Tomato 'Costoluto Fiorentino'
• Tomato 'Falcorosso' F1
• Tomato 'Gardeners Delight'
• Tomato 'Moneymaker'
• Tomato 'Principle Borghese'
• Tomato 'Rio Grande'
• Tomato 'San Marzano 2'