Sowing seeds

Although winter is still lacing gardens and allotments with a frosty edging, it shouldn't put a brake on getting busy with seed sowing, even if you have very little room to spare indoors.

This week, I've begun with my tomato seeds. It's generally reckoned that you should get going with tomatoes about seven to 10 weeks before the last frost date, and if we take an average "frost-free" date of the end of March, then now's the time to sow a few.

Too many will leave you with a forest of greenery in the house, struggling to climb out of their pots and into the garden. Sowing a few will give you a good head start, but leaves you in control of your windowsills, if the weather doesn't co-operate at the right time.

Any small pots will do for sowing tomato seeds. Reused food packaging trays are ideal, but it's important to choose the seed compost well, because it needs to be sterile. The great danger with little fragile seedlings is that they will rot through excess moisture, or succumb to pests and diseases, so avoid the thrifty use of last year's compost that has been sitting around all winter – it's bound to have picked up a few bugs.

Moisten the compost well, then pop it into the trays or pots, and then sow the seeds, about the same depth as the thickness of the seed itself. Sow two or three seeds in each position, and then cover the lot with an open plastic bag, so that it stays moist, but not damp. A warm area out of strong direct light is ideal.

Once the seedlings start to emerge, the bag can come off. They won't need watering yet, just thin them to the strongest-looking seedling per pot, and turn them daily so that they don't grow sideways towards the light.

As soon as they have got two sets of leaves, its time to transplant them into separate pots with a couple of inches' depth to spread their roots, using the same seed compost as you did before. They don't need to be fed anything more than water, as this will just make them grow weak, leggy stems.

To transplant them, use a pencil to make a space in the new container, and lift the seedling by a leaf. Now, here's the clever bit. Sink the seedling well into the hole, so that the first leaves are at soil level. This is because tomato stems will grow roots wherever there is contact with the soil, and lots of root growth will give you stronger plants to move outside later.

Warmth is needed for germination and early seedlings, but once you transplant, cool conditions, ideally about 60 °F, make for stronger growth. If you let the soil dry between waterings, this will toughen them up even more. Apparently, tomato plants also respond to being touched and breathed on, as this encourages stronger stems, too. Then, once they've grown to about 10in, they'll be ready for real soil.