Botanical Name: Spinacea oleracea (hybrid)
Days to Maturity: 20–25 days
Native: Southwest Asia
Hardiness: Frost-tolerant annual. Very cold hardy; fall-sown plants may overwinter even in climates with sub-zero temperatures.
Variety Information: As a baby green, small, dark green and smooth, tender leaves.
When to Sow Outside: 2 to 4 weeks before average last frost, when soil temperature is at least 50°F, ideally 60°–70°F. Successive Sowings: Every 2 weeks until 2 weeks before the first fall frost.
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: ½"
Seed Spacing: 3/4"
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. Mustard baby greens are ready to harvest 20 to 25 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.