Growth potential: As the ground softens up and temperatures become less harsh, it's time to get those early crops bedded in

There's little advantage, unless you are a commercial grower trying to catch an early market, in sowing crops too soon. But if March is kind and the soil warms up and dries out you should this month be able to sow broad beans, cabbage and calabrese, chrysanthemum greens, curly endive, kale, land cress, lettuce, spring onions, parsley, parsnips, peas, radish, spinach and plenty of cut-and-come-again crops: mizuna, komatsuna and red mustard, mibuna, oak-leaf lettuce, saladini, pak choi, rocket and Texsel greens (a type of brassica). Cut-and-come-again crops do well in large tubs. So do land cress, radishes and parsley. The rest produce the best crops in open ground.

But before you launch into an orgy of seed sowing, think carefully how you might best use your space. Brassicas, for instance, tie up ground for a very long time. There is a strong case for ordering young plants instead. Marshalls offer 16 plants each of the cauliflower 'Baldo Delicious', the calabrese 'Marathon' and the spring cabbage 'Excel' for £8.95 (delivery mid- to late March). That's more expensive than seed, but you'll get as many greens as you'll probably want to eat and will have skipped the most nerve-wracking part of raising the crop. Where pigeons are a problem, you may still have to cover the young plants with fleece or netting.

Broad beans are often sown in October or early November so that they crop early in May. This is always a gamble and in this last cold, wet winter, the beans may have rotted rather than sprouted. There's plenty of time to sow again though, setting the beans 5cm deep and 20cm apart in a double row 50cm apart. You can also sow the beans in deep trays (I used greengrocer's wooden trays lined with newspaper) and set them out when they've grown into young plants. They stutter a bit as they find their bearings, but in many ways this is a safer way to get your crop. I like 'Stereo' (Marshalls £1.95) because you can eat the whole pods, mangetout style, as well as shelling the beans. Remember to pinch out the tops of the plants when 4-6 pods have set on the stem below. You can use the green tops in a stir-fry or a risotto.

Garlic is another crop that is traditionally planted in the autumn, to give the bulbs the longest possible growing season before they are lifted in July. But like bean seeds, garlic cloves may have rotted in cold, wet soil this winter. Rust, their greatest enemy, is also prevalent in wet conditions. But you can plant garlic in early March and still hope for a decent crop by July. Set individual cloves 15cm apart in rows 30cm apart, burying them pointed end up so the tufty bit at the top is only just under the surface of the soil.

There are three different kinds of garlic. Elephant garlic (Allium ampeloprasum) produces huge cloves with a mild flavour. It's terrific roasted whole with parsnips, but is a completely different species from ordinary garlic (A. sativum) which can be sorted into hard-neck and soft-neck kinds. Hard-neck varieties such as 'Lautrec Wight', 'Purple Moldavian' and 'Purple Wight' have bigger but fewer cloves than soft-neck kinds and won't keep beyond Christmas. Soft-neck kinds such as 'Albigensian Wight', 'Cristo Wight' and 'Solent Wight' produce lots of smallish cloves, and in cool conditions will keep until spring. Which? Gardening reckons that 'Solent Wight' (Marshalls £4.75 for two bulbs) is the best variety to choose. From a spring sowing it cropped heavily in their trials both in the south and in Scotland.

The Wight tag marks the varieties developed on the Isle of Wight by Colin Boswell, who is so mad about garlic that he spent weeks on horseback ranging through the Tien Shan mountains of Kazakhstan and Kyrgyzstan searching for the beginnings of all garlics, the mother of all bulbs. Like the leek, garlic belongs to the huge family of alliums, the majority of which originated in these mountains.

It's long been thought of as a magic plant – proof against vampires and things that go bump in the night. Turkish fishermen still hang it in their boats for good luck. But it's also reckoned to be a decent antiseptic and effective in warding off colds. Forget the expensive pills. Eat the real thing instead. To get good crops you need light, well-drained soil, not too acidic. The bulbs will be ready to lift when the oldest leaves start to turn yellow. After lifting, you'll need to dry and "cure" the bulbs either outside in the sun, or if there isn't any (remember last summer?) inside a greenhouse or cold frame. When the bulbs are completely dry, make them up into strings, plaiting the dry leaves together and working in extra heads as you go. For green garlic, mild and squidgy, just dig bulbs straight from the ground, before you lift and dry off the main crop. Elephant garlic (Marshalls £7.95 for a pack of 12 cloves) is particularly good used green.

Spinach is a rewarding crop for home growing because it's quick, easy and can be used in plenty of ways. The youngest leaves, tossed raw with crispy bacon, make one of the best salads you can eat. It's good kept as a cut-and-come-again crop, which will give you baby leaves to pick over a long season. And of course, the full-size leaves are gorgeous cooked and whirled up with plenty of nutmeg and butter. The secret is to sow as thinly as you can, either direct into the ground, or, if you have a greenhouse or cold frame, in a compost-packed length of gutter to transplant into the open ground later on.

Seeds germinate quickly (usually within a week) and at this early end of the season, plants should not bolt too quickly. Unlike garlic, which needs sun, spinach does well in part-shaded ground, provided the soil is rich and moist. Successional sowing, every three or four weeks, should provide a crop over a long season, though it's a less rewarding thing to grow in summer than in late spring. Drought increases its propensity to bolt. One of the prettiest varieties is 'Bordeaux' (Thompson & Morgan £1.69), red-stemmed with the dark green leaf also veined with red. It is sweet and succulent enough to use raw as a baby leaf, but also cooks well. 'Campania' (Marshalls £1.85) is also worth trying. It did well in the Royal Horticultural Society's trials, proving slow to bolt and producing a lush crop of thick, dark leaves.

S E Marshall, Alconbury Weston, Huntingdon, Cambs; call 01480 443390 or order online at marshalls-seeds.co.uk. Thompson & Morgan, Poplar Lane, Ipswich, Suffolk; call 01473 695225 or visit thompson-morgan.com