Botanical Name: Brassica oleracea
Days to Maturity: 25–30 days
Hardiness: Biennial grown as an annual, kale is very cold hardy and may overwinter in milder climates.
Variety Information: Small, frilly, dark green leaves with reddish purple veins and stems.
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. Sow indoors any time of year, with indoor temperatures 60°–75°F. Successive Sowings: Every 2 weeks for a continual supply.
Days to Emerge: 5–10 days
Seed Depth: ⅛"–¼"
Seed Spacing: ¾"
Thinning: Not required
Harvesting: When seedlings emerge, the first pair of leaves to show are the cotyledons, which can look very different from the leaves that follow, called "true" leaves. Red Russian Kale baby greens are ready to harvest 25 to 30 days after sowing, when they have true leaves, at 2"–4". Slow growers, or cool growing temperatures may require more time. Harvest by cutting just above the soil line. For more than one harvest (up to 3 before flavor declines) leave about 1/2" of leafy growth on the small plants so they can regenerate.