Plant Broccoli in Zone 4a

Seed-starting, transplant & harvest dates for USDA Zone 4a

Start indoors

Mar 29

Transplant

Apr 26

Harvest (~65d)

Jun 30

Zone 4a averages 135 frost-free days, running from a last spring frost around May 10 to a first fall frost around September 22. Broccoli needs roughly 65 days from planting out to first harvest, so it uses about 48 percent of that window. Broccoli is a half-hardy crop, which is what decides where in the window it belongs.

Because broccoli needs a head start, sow seed indoors around Mar 29, about 6 weeks ahead of the Zone 4a last frost. Transplants go out around Apr 26. Starting earlier than that in Zone 4a usually backfires: plants outgrow their cells and stall when they finally hit cold soil.

Planting broccoli for a fall harvest in Zone 4a

Yes. Sow broccoli by July 26 in Zone 4a. That is 58 days before the average first frost, which covers the 65 days to maturity plus about two weeks for the slower growth that comes with shortening days, minus the roughly 21 days broccoli keeps going once light frost arrives.

Fall broccoli avoids the spring problem of heads buttoning up when temperatures spike. Start transplants indoors in midsummer rather than direct sowing into hot soil.

Fall sowing opens

Jul 5

Sow by (last chance)

Jul 26

Fall harvest

Sep 29

Fall dates are counted backward from the Zone 4a average first frost, not forward from a sowing date. See the fall planting calendar by zone for the full method.

Spring vs fall broccoli in Zone 4a

Planting	Sow or start	In the ground	Harvest
Spring	Mar 29	Apr 26	Jun 30
Fall	by Jul 26	Jul 26	Sep 29

Last spring frost

May 10

First fall frost

Sep 22

Growing season

135 days

Broccoli in nearby zones

Broccoli in Zone 3b (colder) Broccoli in Zone 4b (warmer) Full Broccoli grow guide Zone 4a planting calendar

Other crops in Zone 4a

Tomatoes in Zone 4a Peppers in Zone 4a Cucumbers in Zone 4a Lettuce in Zone 4a Zucchini in Zone 4a Carrots in Zone 4a Beans (bush) in Zone 4a Peas in Zone 4a Spinach in Zone 4a Kale in Zone 4a Onions in Zone 4a Garlic in Zone 4a Potatoes in Zone 4a Squash (winter) in Zone 4a Corn in Zone 4a Radishes in Zone 4a Beets in Zone 4a Eggplant in Zone 4a Basil in Zone 4a Cilantro in Zone 4a Parsley in Zone 4a Pumpkins in Zone 4a Sunflowers in Zone 4a

Frequently asked questions

When should I start broccoli in Zone 4a?

Start broccoli seeds indoors around Mar 29 (Zone 4a).

Can I direct sow broccoli in Zone 4a?

Broccoli is best started indoors and transplanted in Zone 4a rather than direct sown.

Can I plant broccoli in the fall in Zone 4a?

Will broccoli survive frost in Zone 4a?

Broccoli is a half-hardy crop and keeps going roughly 21 days past the first light frost in Zone 4a. A row cover or a straw mulch buys more.