Broccoli is easy to grow and packed full of nutrition. But it's tricky to know when to harvest broccoli for peak ripeness. Heads form slowly and remain on the plant a long time. Broccoli also forms smaller heads as side shoots. Here are some clues for when your broccoli is ready for your dinner table.
To produce large heads of broccoli, wait until the central head ceases to increase in diameter. The heads (actually a set of flower buds) should be tight, with a dense set of small, green buds. Flowers do not open all at once, so the first sign of yellow means that the head should be harvested immediately to avoid bitterness. Hot spells (highs in the 80s) for more than one week will cause a quick flowering, so watch plants carefully and be prepared to harvest immediately.
In most broccoli varieties, numerous side shoots form as well. These smaller heads continue to mature after the central head is harvested, and are the best way to have a second - and sometimes a third - crop of broccoli from a single plant. Follow the same guidelines for when to harvest. Cut the head when it's still deep green and there's no sign of yellow. Once the main head starts to yellow, the plant often goes to seed without forming side shoots.
Harvest in the morning before the soil warms up for best flavor. Leave 2-3 inches of the main stem on the plant. Cut with sharp scissors or a knife to avoid damaging the stem. The side shoots that grow are likely to form more open or spreading heads than the central stem, but they're every bit as tasty.
Once broccoli heads are harvested and any side shoots you want are cut, the plant is finished for the season. Pull it and put it in the compost to make room and nutrients for next year's crop.