Botanical Name: Brassica oleracea var. botrytis
Days to Maturity: 75–100 days
Hardiness: Frost-tolerant biennial grown as an annual
Plant Dimensions: 36" tall, 24" wide
Variety Information: An old, reliable European heirloom introduced in 1890. Large plant with blue green leaves and a 5"–6" lime green central head composed of many smaller spiraling florets.
Attributes: Good for Containers
When to Sow Outside: Not recommended. 1 to 2 weeks before your average last frost date, or 10 to 12 weeks before your average first fall frost date. In Mild Climates, sow in early fall for winter harvest.
When to Start Inside: RECOMMENDED. 4 to 6 weeks before transplanting outside after your average last frost date, or 12 weeks before your average first fall frost date. In mild climates, sow in fall for harvest in late winter and early spring. Ideal soil temperature for germination is 70°–85°F, cooler (60°F) growing temperatures thereafter.
Days to Emerge: 8–10 days
Seed Depth: ¼"
Seed Spacing: A group of 3 seeds every 24"
Row Spacing: 24"–36"
Thinning: When 2" tall, thin to 1 every 24"
Harvesting: Harvest heads as soon as they have developed. Head should be firm and solid. Cut at the base where it connects with the stem using a sharp knife. Remove entire plant after harvest since romanesco rarely produces side shoots like true broccoli. Harvest in the morning if possible. If harvested in the heat, dunk in ice water to reduce "field heat" and increase storage time. Allow to drain before storing.