Broccoli is an annual cool-season crop hardy to frosts and light freezing. Broccoli tends to grow best in the fall due to the more predictable cool weather. Headed broccoli is the most common form in the United States, with big central heads closely packed with buds. Did you know? After you've harvested the main head, you can encourage "side-shoots" to form by adding fish meal around the base of the plant.