Botanical Name: Brassica oleracea
Days to Maturity: 55 days
Hardiness: Biennial grown as an annual, kale is very cold hardy and may overwinter in milder climates.
Plant Dimensions: 12"–30" tall and wide
Variety Information: Clumps of bluish-green leaves with curly, frilly edges off a central stem.
When to Sow Outside: 1 to 2 weeks before your average last frost date, when soil temperature is above 45°F for spring/summer crop; 10 to 12 weeks before your average first fall frost date for fall crop; and in mild climates, fall for very early spring crop.
When to Start Inside: RECOMMENDED: 4 to 6 weeks before your average last frost date. For a fall crop, start 12 to 14 weeks before your average first fall frost date, transplanting after 4 to 6 weeks. Ideal soil temperature for germination is 65°–85°F.
Days to Emerge: 5–10 days
Seed Depth: ¼"
Seed Spacing: A group of 3 seeds every 18"
Row Spacing: 24"
Thinning: When 1" tall, thin to 1 every 18"
Harvesting: Outer leaves can be harvested as baby greens when 2"–3" tall, any time when full-sized beginning with the lowest, or the whole plant can be cut off at ground level at maturity. For fast regrowth, harvest up to only ⅓ of the plant at a time.