I plant my broccoli in the early spring, harvest the first central head with about 5-6″ of the main stem. Then, I leave the rest of the plant in the ground and harvest side shoots the rest of the season. You may find that your side shoots bolt more quickly in the summer time, so harvest them sooner. Come fall when the temps cool down, you’ll find your broccoli is producing beautiful side shoots once again. At this point, those critters that were eating your brassica plants have since left the garden and you’ll enjoy bug free broccoli the rest of the season.
If you find them gross, which most of us do, I cover mine with a light row cover to keep those lovely white cabbage moths from laying their eggs on my plants. What does this mean? No cabbage worms eating your broccoli, kale, and cabbage. I prefer not to spray anything in our garden so I focus on prevention and a healthy ecosystem rather than treatment.
I highly recommend planting cilantro all around your garden and letting it go to seed. It attracts all kinds of beneficial insects which help control the unwanted pests. If I have cilantro (coriander) blooming in my garden. I rarely have a large population of green cabbage worms. We also don’t discourage wasp in the garden. I once saw a wasp eat a large cabbage worm in about 3 seconds. It was so fast that when I reached to grab my camera which I always keep with me in the garden. He was already finished. It was amazing.