A closer look at how broccoli develops will help you grow perfect heads.
Broccoli is temperature sensitive. When plants sit exposed to cold below 40 degrees for a week or two, they suffer chilling injury. This triggers heads to form way too early. On the other end of the scale, if you plant too late and the weather gets hot, you’ll get the same early blooming, so plant your broccoli on time. The ideal temperature for broccoli is between 65 and 80 degrees. For planting dates, check with your regional Extension office.
Broccoli, like other cole crops, needs a good supply of nitrogen and other nutrients to be readily available in the soil when you plant. This is because the plants go through various stages of growth, one of which is to store nutrients in the outer leaves to feed the fast-growing head as it forms. The plant cannot take up nutrients fast enough to do this at the time of heading, so it is important to start out with well-prepared soil. Be sure that you amend the soil properly and add nutrients according to the results of a soil test.
For the most tender, succulent spears, be sure the soil stays moist. Water stress shows up as tough, stringy spears.
Broccoli plants have tiny buds in the axils of the leaves. After you harvest the large central head, these tiny buds will grow into delicious bite-sized shoots for a good second harvest.