Botanical Name: Brassica oleracea var. gongylodes
Days to Maturity: 50–69 days
Hardiness: Biennial, grown as an annual
Plant Dimensions: 10"–12" tall, 8"–10" wide
Variety Information: Enlarged, bulblike portion of stem forms just above soil surface. Flavor is radish-like, between an apple and a mild turnip. 'Purple Vienna' has a reddish-purple, slightly flattened globe with tender white interior. 'White Vienna' is similar in shape and habit but is light green on the outside.
Attributes: Good for Containers
When to Sow Outside: 4 to 6 weeks before your average last frost date, or when soil temperature is at least 45°F, ideally 65°–80°F. Also sow in late summer for fall harvest. Mild Climates: Sow in fall and winter for cool–season harvest.
When to Start Inside: 4 to 6 weeks before your average last frost date, and 10 to 12 weeks before your average first frost date, transplanting in 4 to 6 weeks.
Days to Emerge: 10–14 days
Seed Depth: ¼"–½"
Seed Spacing: A group of 3 seeds every 4"
Row Spacing: 12"–18"
Thinning: When 2" tall, thin to 1 every 4"
Harvesting: Smaller kohlrabi is the sweetest and most tender; harvest when 2"–3" in diameter. Those much bigger than the size of a tennis ball won't be as tasty and often have a pithy or woody flesh. Harvest by cutting stems between the soil and where the stem widens.