I saw on Youtube before, for broccoli they will create new head, but for cauliflower will create new small plant and we can plant them again?
For cabbage, after cut the stem, there are baby cabbage (we called it here) and yummy to make stir-fried side dishes 😊 but yeah they never create big cabbage head again
The new, smaller plants remain on the main stump which has been cut... Yes, they might 'only' maje small versions of the original plant, but this will depend on the plant's position and nutriment: enriching the soil, mulching heavily, or great positioning amongst other symbiotic plants will allow new growth to flourish significantly.. Double-digging and creating mounds can help with this: here's a book that I highly recommend to study if you can (you may find it in PDF form online):
