What spacing do you use? Most need about 2ft I think and they are hungry plants too
I grow igloo early in the year, can be grown large if given enough space or this year I grew them just 30cm apart for mini cauliflowers. They were bred for that purpose think. I sow them end of february in modules, plant out end of march/start april, cover with fleece then netting and harvest june/July. I don't grow overwintering ones. They'll go in a bed that will have had compost spread during the winter. Also I grow autumn romanesco, its too late to try that this year though. Can recommend, they look great
Almost 8lb one from last year and smaller one this year