Guide to Growing Broccoli
DK - The Complete Gardener's Guide , 2011 Dorling Kindersley Limited
Purple sprouting broccoli is a cold hardy biennial plant that must overwinter before heading into spring. The plants are covered with smallish, very sweet tasting purple heads that turn green when cooked.
Packed with vitamins and highly ornamental, broccoli is an asset to any garden. Choose from white or purple winter sprouting types, which bear an abundance of tender stems, or the large domed heads of summer calabrese.
How to Grow
Broccoli grows best in a sunny site in rich soil that has been improved with plenty of well-rotted organic matter, such as garden compost or manure. The two types, sprouting and calabrese, are sown in different ways. Sow sprouting broccoli under cover into small pots or modules in early spring for early varieties, midsummer for late crops. From mid-spring it can also be sown directly outside in seedbeds and covered with cloches or fabric. Plant out or transplant seedlings into their final positions in late spring, once the frost has passed, leaving 24 inches (60 cm) between plants and rows. Summer calabrese dislikes root disturbance and should be sown outside where it will grow in soil that has been raked to a fine tilth. Sow in drills 1/2-inch (2 cm) deep, 12 inches (30 cm) apart, with 18 inches (45 cm) between rows.
Keep both types well watered in the summer, and cover with netting so the heads are protected against birds. The heads can become heavy, so support plants using canes, or earth up the base of the stems. Harvest summer or winter heads before the tiny flowers within the florets open. Pick sprouting broccoli often to encourage an extended crop; the more you pick, the more it crops. Cut calabrese heads in the summer when less than 4 inches (10 cm) across to encourage more flowering shoots; use a sharp knife to cut the florets, starting with the central head.
Types of Broccoli
Calabrese is a quick-growing crop and is harvested the summer after sowing. Pick the heads while they are small for the largest harvest. Varieties to try include ‘Arcadia’ F1, ‘Belstar’ F1 and ‘Fiesta’ F1. On the other hand, sprouting broccoli is a winter staple and will crop for several weeks; harvesting the stems encourages growth. Sprouting broccoli produces purple heads (P) or white (W), depending on variety. Varieties to try include: ‘Claret’ F1 (P), ‘Early White Sprouting’ (W), ‘Rudolph’ (P) and ‘White Star’ (W).
Watch Out for These Pests and Diseases
All brassicas, like Brussels sprouts and cabbage, suffer from similar pests and diseases. Cabbage root fly lay eggs near brassica plants, hatching into maggots that eat the roots. Plants are weakened and may die. There are no chemical controls; fit brassica collars around young plants. Pigeons may also attack plants during winter and spring, eating the foliage and flowers. Cover plants with netting, or build a scarecrow to avoid damage.