Germination temperature: 45 F to 85 F
- 70 F to 75 F is optimum.
Days to emergence: 7 to 10
Seed can be saved 5 years.
Usually direct-seeded as transplants tend to go to seed (bolt) prematurely.
requirements differ somewhat by variety, so consult seed sources for
best practices. Even so, this crop can be somewhat unpredictable. In
general, plant older “forcing” varieties in spring, then cut back
plants in late summer to produce heads about 4 to 6 weeks later. Newer
“nonforcing” varieties do not need to be cut back, and will form heads
in fall or even in summer. They generally do not hold their quality as
long as forcing varieties.
Direct-seed about 4 to 6 weeks before
average last frost. (Nonforcing varieties can be sown through through
mid-summer for fall and winter harvest.) Plant seeds ¼ to ½ inch deep,
3 to 4 inches apart, in rows 24 inches apart. Thin to 10-inch spacings.
Mulch to retain moisture and suppress weeds.
Mulch crowns from harvested plants. If conditions are mild, you may get an additional harvest in spring.