Botanical Name: Brassica assorted species (hybrid)
Days to Maturity: 25–30 days
Native: Widespread; probably Eurasia
Hardiness: Frost-tolerant annuals
Variety Information: Various leaf shapes, from serrated to rounded, with a mix of green and red 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: ⅛"–¼"
Seed Spacing: ¾"
Thinning: Not required
Special Instructions: Good air circulation is important to help prevent fungal disease. If using a fan, avoid aiming the fan directly at the growing medium as it may dry the medium quickly; instead, bounce the airflow off a neighboring wall or the ceiling to create air movement in the general area.
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 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.