When to Plant Cabbage

Spring: early, but not too early

Spring cabbage has to form heads before summer heat, since Utah State says growth and quality drop once temperatures pass about 80°F. So plant early. Utah State sets transplants out 2 to 3 weeks before the average last frost, and seed can be sown at the same time.

The soil sets a floor. Cabbage seed needs at least 40°F to germinate and does best at 60 to 85°F. A University of California table shows how much temperature matters: seedlings take about 15 days to emerge in 50°F soil, about 9 days at 59°F and about 6 days at 68°F. Colorado State suggests measuring soil temperature at 8 a.m., 4 inches deep. Because cabbage germinates so slowly in cold ground, transplants are the standard spring method.

There is also a reason not to rush. Clemson Extension warns that a stretch of 10 or more days between 35 and 50°F, after plants have been growing well, can trigger bolting, so the plant sends up a flower stalk instead of a head. Planting well ahead of the recommended window raises that risk without gaining much.

When to start seeds indoors

Extension services disagree on how long to grow cabbage transplants:

• Utah State: 6 to 7 weeks, until plants have 4 to 6 true leaves.
• Maryland Extension: 4 to 6 weeks.
• Iowa State: 4 to 5 weeks.

Count back from your transplanting date. The indoor-start window in the dates for your zone above covers this full range. Harden plants off outdoors for several days before planting, starting in a shaded, sheltered spot.

Fall: count back from the first frost

A fall crop forms its heads as the weather cools, away from the heat that hurts spring cabbage. Utah State’s method is to choose an early variety and plant it 50 to 75 days before a target harvest date about 1 to 2 weeks after your first fall frost.

Regional calendars often start earlier than that formula suggests, and they give a useful reality check:

• Iowa: Iowa State sets fall transplants out between mid-June and mid-July and grows only early varieties for fall.
• Maryland: sow fall seed outdoors about 3 weeks before transplanting, in a spot with some protection from the sun, and keep it well watered.
• Colorado’s Front Range: Colorado State says direct seeding in midsummer gives the best fall quality in the warmer parts of the state.

If you grow a late or storage variety, start earlier than the formula, because those can need 100 days or more from transplanting. Nebraska Extension’s fall formula adds about 14 days for slower growth in shortening days, plus the time to raise transplants if you grow your own.

Clemson notes that fall cabbage can be direct-seeded. Summer soil is warm enough that seed comes up quickly, but keep the row moist.

Mild-winter regions

Where frost is rare, cabbage is a fall-to-winter crop. Plant from late summer into winter and harvest before spring heat.

• Florida: UF/IFAS lists a fall-through-winter window for all three regions, ending a little sooner in South Florida.
• Phoenix low desert: the Maricopa County calendar plants cabbage from late summer into winter. It lists 80 to 90 days from transplants and 120 to 130 days from seed.
• Lower Rio Grande Valley, Texas: Texas A&M starts seed in flats from early fall into early winter and transplants after about 3 to 4 weeks. Plants go out no earlier than early October and do best from mid-October on.

Check the dates for your zone above for the exact window where you live.