The cabbage family is vital for every veg grower.

There's such a wealth of brassica plants - broccoli, cabbages, caulis, sprouts, kail, neeps and even radishes - that one or more are always ready at any time of year. They're indispensable over the long winter months too. I need more plants than I can fit into a three-year crop rotation, never mind a four-year one.

Nothing beats freshly cut broccoli spears from the garden, when they're at their tastiest and most nutritious. Like sprouts, broccoli loses most of its health-giving properties within a week of harvesting. And, if frozen or part-frozen between field and supermarket, it's scarcely worth eating. Even though cabbages and caulis stay fresh for a few more days, they too are at their succulent best straight from the garden.

But I can't blame anyone for deciding not to grow these cracking vegetables. They are a hassle. Brassicas are hungry for feed and space and a magnet for countless pests and diseases. You must be committed to take them on.

Whether you've grown plants from seed or bought them by mail order or at a garden centre, most varieties should be planted out this month. There are some exceptions, like spring cabbage, so check this is the right planting time before buying.

Varieties mature at different rates, taking anything from 16 weeks to a year, so plant a small number of several different varieties, rather than lots of one or two. This provides a harvest throughout the year, rather than one wasteful glut over a fortnight.

Give brassicas plenty elbow room in open ground - never containers, however large. Cabbages need 45cm spacing and may not heart up properly if crammed together. Cauliflowers are especially demanding, so like most of the larger varieties - sprouts and broccoli - they should be grown 60cm apart. Close planting may result in "blindness", where no curd forms. Blindness can also be caused when plants are grown in thin, sandy, overly free-draining soil or in soggy, waterlogged ground.

Rich, moisture-retaining soil is therefore essential. Dig in compost and spread pelleted chicken manure and seaweed meal. After making a small hole for a plant, fill with water and plant as deeply as possible, leaving the bottom pair of leaves just above ground level. Tamp firmly round young plants. Some varieties grow to 60cm or more so they need a firm base to prevent windrock. Once sprouts are fully grown, I even attach them to small wooden posts.

Cabbage rootfly is the brassica's first fatal foe. The fly lays eggs close to the stem and its larvae tunnel down to the roots and consume the lot, thereby killing the cabbage. Prevent this by covering the crop with fleece, carefully pegging the material down to keep the fly out. Alternatively, wrap a cabbage collar - homemade or purchased - round a plant's stem. Young brassicas enjoy the best protection against cabbage rootfly and damaging wind when they're inside a large yogurt pot. Cut off the base, invert the pot and place round the young plant.

Our mollusc friends and cutworms present the next challenge. Wrap sticky copper tape round yogurt pots, if you're using them, or smear something greasy like Vaseline round the outside of the pot. Otherwise, use beer traps or the biological control Nemaslug. Cutworms, the fat larvae of noctuid moths, graze through tender stems and fell young plants. Prevent this, by carefully trowelling over the ground to expose any pests before planting.

Vigilance is all with brassicas. From next month onwards, look out for cabbage white butterflies flitting around your plants. They lay eggs on leaves and the larvae strip them bare. Cover the plants with fleece or fine insect net. Use hoops or a frame tall enough to keep the fabric off any leaves, since the butterflies can lay eggs through netting.