Follow packet directions. Broccoli has a relatively shallow, fibrous rooting system. Cultivate carefully or, even better, mulch. The heads of broccoli are really flower buds. These must be harvested before the flowers open or show yellow.
Mature heads measure three to six inches across.
Lateral heads that develop later are smaller. Downy mildew, sclerotica rot and blackrot. Harvest with 6 to 8 inches of stalk. Harvest sprouting and other types according to packet instructions. This site was developed for the Arizona Cooperative Extension , College of Agriculture , The University of Arizona .