More in Outdoors
Moist, well-drained, fertile soil suits most brassicas, so it is best to work in plenty of organic matter well in advance of planting. Lime should be added to soil with a pH lower than 6.8 to prevent clubroot, and it is sensible to rotate crops to prevent buildup of the disease in the soil. Firm soil keeps the plants stable in winter weather, so do not dig the bed deeply before planting. Brassicas prefer full sun, but will tolerate partial shade, while taller plants, such as Brussels sprouts, need to be staked on windy sites.
Most brassicas are best sown into an outdoor nursery bed or modules under cover in spring, and transplanted into their final positions as young plants. However, sow summer sowings of calabrese and kohlrabi directly into seedbeds in their final positions.
Brassicas are cool-weather crops and tend to bolt during hot, dry spells. Water transplants daily and mature plants once a week in dry weather. Watch for early signs of pests and diseases. The cabbage root fly is common and lays its eggs on all brassicas, so take preventative measures with all seedlings. Cover the plants with fleece to prevent butterflies from laying their eggs. Slugs, snails, aphids, and whiteflies all enjoy brassicas, and pigeons may destroy winter crops. Take measures to avoid clubroot.
Hardy winter and spring crops will stand well in the garden and can be harvested at any point, but eat summer crops fresh, before they bolt.
Netting against pigeons Winter brassica crops are a favorite with hungry pigeons. Preempt their feast and protect plants by covering the brassica bed with netting (image below) secured to stakes or wires that are sturdy enough to last through winter weather.
Thwarting cabbage root flies Female flies lay their eggs at the base of young plants, so buy collars, or make your own out of thick paper or carpet underlay, to prevent this. Use 6-inch squares of your chosen material and cut a slit in the center of each, so that it can be placed snugly around the base of the plant.
Coming back for seconds Broccoli and calabrese continue to produce secondary spears after the central one is cut, and frequent harvesting encourages even more to be produced. When harvesting summer cabbages, leave 2-inch stumps and cut a cross 1/2-inch deep in the top of them. This encourages a loose head of leaves to develop, giving you a second crop.
Cauliflower (image 1)
Best in rich, heavy soils with plenty of manure. Snap outer leaves over each curd to protect them from sun and frost.
Kale (image 2)
Hardy and tolerant of poor soil, kale is easy to grow. Colorful, textured varieties brighten up the winter garden.
Brussels sprouts (image 3)
Harvest this classic winter vegetable from the base of the stem upward, by snapping off each sprout by hand.
Kohlrabi (image 4)
Eat the swollen stems of these fast-growing exotics in salads or stir-fries. Harvest when no larger than a tennis ball.
Excerpted from Simple Steps: Vegetable Gardening
© Dorling Kindersley Limited 2007