How to Prune cauliflower 'Igloo'?
No pruning required

cauliflower 'Igloo' · Brassica oleracea 'Igloo'
Sow seed outdoors in deep, fertile but firm, soil that isn't too acidic. If space is limited, start the seeds in modules or seedtrays and plant outside when big enough to handle easily (about 5 or 6 leaves). Watering through the summer months is very important. For more advice see vegetable cultivation
No pruning required