Early Purple Sprouting Broccoli Seeds (Aimers International) Heirloom Vegetable. Variety originated in UK. Rather than produce a single large head, this winter sprouting broccoli produces many small purple florets. Needs 6 weeks of 10°C (50°F) to initiate floret development. Harvest the central floret as soon as it forms to promote the development of side shoots. Matures in 150 days.