Botanically, broccoli closely resembles cauliflower, although the heads are usually smaller. In England, where many varieties are grown, there is great variation in the leaves and general habits of the plants. In this country the plants are more hardy to frost than cauliflower and the heads require more time to reach marketable size. The plants are also very sensitive to heat and demand a liberal and constant supply of moisture.
Broccoli is an important crop in England, being grown on an extensive field scale in some sections. In this country it has never been regarded as a satisfactory vegetable for commercial purposes, because of its inferior quality compared with cauliflower, and also because of the greater difficulty with which it is grown. Henderson claims that the crop fails two seasons out of three, but when successful it is highly profitable. Broccoli thrives best in northern sections.
It should be produced as a late crop, sowed in the open some time during May and transplanted in the field about six weeks later. The plants may be set 18 inches by 30 inches. The soil should be deep, rich and moist. The leaves are bent, pinned or tied to blanch the heads, as in the production of cauliflower. White Cape and White French are the leading varieties grown in the United States.