Hello,

This looks to be the work of the cabbage worm. The cabbage worm eats on cabbage, cauliflower and broccoli. The white moths/butterflies you see flying around are the adults. They lay eggs on the underside of the leaves. When the egg hatches the green worm starts to eat on the foliage and if there are enough of them can do a fair amount of damage on the leaves. They will also get into the head and can do a fair amount of damage and here they are hard to find and remove.

Seven can be powdered onto the plants to kill and protect them from the cabbage worm. Two biological pesticides, Bt and spinosad, give excellent cabbage worm control when applied between rains. Bt is less likely to interfere with the work of other beneficial insects compared to spinosad. Organic pesticides are often needed in late summer to protect fall cabbage and broccoli from serious infestation and controls cabbage worms that are hiding among the growing florets. A single treatment with Bt two weeks before harvest can make a huge difference in the quality of cabbage and broccoli.

Cauliflower likes temperatures in the 60s. In young cauliflower plants there is a fine balance between leaf and head growth. Any stress tips the balance toward premature heading, or “buttoning,” when the plant makes tiny button-sized heads. This can happen when it’s too hot or too cold. This also happens if plants sit in packs too long, or are stunted by drought or poor soil.