From Osborne Seed:
Overwintering cauliflower typically can be harvested from late January to mid-May in the Pacific Northwest. Large framed plants yield heavy, beautiful heads at a time when other storage crops are starting to wane. Recommended seeding is from June to late July for transplant July to August, depending on your conditions and desired harvest window.
Care: Plant 20-30″ apart in rows 24-36″ apart in full sun, cool moist soil.
These hardy varieties hunker down during the cold temperatures and heavy rains of winter, waiting to take off when light and warmth return. Harvest in late winter and spring. See our Fall & Winter Vegetable Guide for specific planting/harvest times & freeze-out temperatures.