Broccoli is ready to be picked when the buds of the head are tight and firm. This usually occurs before the yellow petals appear at the head of the broccoli. If yellow petals are already blooming, pick the broccoli immediately.
Pick broccoli in the morning before the soil has the chance to heat up. When harvesting broccoli, cut the heads off the broccoli plant, and remove a few inches of the stem. The broccoli plant should have side shoots that continue growing even after the head of broccoli is removed. Some broccoli plants can be harvested throughout an entire growing season. Harvested broccoli can be stored for up to five days in the refrigerator.