Broccoli is slightly more bitter in flavour than cauliflower, but often cooked the same way and even eaten raw. The green stems and flower heads are rich in minerals, vitamins and fibre.
Plant seeds in compost-enriched soil, sowing them from February to June in hot climates, or in any cooler months. Plant nasturtiums around to keep aphids away.
Grow for about 10 weeks. After picking the main flower head, small, tasty side shoots continue to grow for several weeks, so keep picking to promote new growth.
To grow the substantial flower-bud heads sold in the supermarket as broccoli, you need to select varieties of calabrese, also called green sprouting. "Romanesco" has pale green, pointed heads and buds; and there is purple-sprouting broccoli, where the leafy shoot tops and small bud clusters are eaten.
Broccoli is sown in spring, or in summer and autumn in mild areas for use in late autumn, winter and early spring. Some varieties have greater heat tolerance.
Like all brassicas, they need a minimum soil pH of 6; add lime if needed. Do not grow them on newly manured ground; instead, dress soil before sowing or planting with a high-nitrogen fertiliser.
Sowing and Planting
Broccoli does not like being transplanted; sow it in in situ in succession (or as directed on the packet), 2-3 seeds together every 15cm (6in), in rows 30cm (12in) apart, and thin to the strongest seedling. You can sow broccoli in a seedbed or in modules in a cold frame; plant out from summer or autumn, 60cm (2ft) apart each way. Plant them deeply and water well until established.
Grow the first sowings of broccoli under protection if this is necessary in spring. Do not let plants dry out; water generously as the flowerheads are forming. Broccoli is vulnerable to winter wind damage, so earth up stems and stake tall plants in autumn. You may need to net against bird damage.
The first and largest flowerheads of broccoli will be ready to cut after 11-16 weeks; if you need then feed with a high-nitrogen fertilizer, a second crop of smaller sideshoots will develop. Wash heads well as creepy-crawlies often lurk in the creases. Harvest sprouting broccoli from late winter onwards; pick shoots regularly to encourage more.