This important member of the cabbage family, known botanically as Brassica oleracea var. gemmifera (Cruciferae), originated in Belgium. The popularity of the vegetable is due not only to the fact that picking can be extended over a long period, but it can stand up to severe winter weather. It is indeed one of the most valued of brassica crops. Brussels sprouts need a deeply-worked, rich, firm soil, plenty of room for development and a long season of growth.
Cultivation To produce compact, firm sprouts, it is essential to have firm ground and an attempt should be made to follow a crop for which the ground has already been well manured. Alternatively, dig in well-decayed manure in the autumn. Late preparation, loose soil or fresh manure results only in lush growth and loose sprouts. If manure is not available apply 85g (3oz) of superphosphate and 28g (1oz) of sulphate of potash per sq m (sq yd) prior to planting. Even when manuring has been carried out the addition of half the recommended quantities of fertilizer will be found beneficial. For early or late varieties, sow in a prepared seed bed in a sheltered position in the middle of March. Transplant to permanent positions in late May and firm well. Under normal growing conditions allow 0.8m (2.5 ft) between the plants and in the rows, but with vigorous growing varieties on good growing soil allow 1m (3ft) between the rows and 0.8m (2.5 ft) between the plants. As a precaution against cabbage root maggot and club root disease, dip the washed roots of the young plants into a thin paste using 4 percent calomel dust and water. Water the young plants if the weather is hot and dry. Hoe the soil frequently to keep down weeds. Apply 28g (1oz) of Nitro-chalk in September or October. In open windy areas it is as well to stake plants in the autumn if growth is at all vigorous. Remove yellow leaves as they appear. Pick the sprouts as they are ready. Do not remove the tops until the end of the winter as this helps in the formation of sprouts and gives protection during severe weather. Varieties `Cambridge No. 1′ (early); `Cambridge No. 2′ (mid-season); ‘Cambridge No. 5′ (late); `Harrison’s XXX’, a good heavy cropping early; ‘Jade Cross’, a newer F.1. hybrid, very early, producing a heavy crop of dark green sprouts; ‘The Aristocrat’, an excellent mid-late variety producing medium-sized sprouts with perfect flavor.