The cabbage worm has found our garden. Man the cannons! Boil the oil!
Actually, you can just brush them off with your fingers.
Look for small green worms and/or tiny pimple-like eggs on the undersides of the leaves of broccoli, cabbage, kale, brussels sprouts, and related plants. A big clue is the chewed-up holes in the leaves. Once they're brushed onto the ground, they can't find their way back.
The broccoli is starting to head, at least the ones in the communal garden. The head will start as a tight button that slowly expands.
A mature broccoli looks like this:
Harvest it right away, because two days later, it will look like this:
Cut the broccoli just below the head but above the side shoots. Side shoots are mini-heads (actually, one-quarter the size of the main head) that start growing if the main head gets cut off. If you leave the side shoots to grow, you'll get the equivalent of another head in about two weeks.