Plant Onions in Zone 6b

Seed-starting, transplant & harvest dates for USDA Zone 6b

Start indoors

Feb 4

Transplant

Apr 1

Harvest (~100d)

Jul 10

Zone 6b averages 186 frost-free days, running from a last spring frost around April 15 to a first fall frost around October 18. Onions needs roughly 100 days from planting out to first harvest, so it uses about 54 percent of that window. Onions is a hardy crop, which is what decides where in the window it belongs.

Because onions needs a head start, sow seed indoors around Feb 4, about 10 weeks ahead of the Zone 6b last frost. Transplants go out around Apr 1. Starting earlier than that in Zone 6b usually backfires: plants outgrow their cells and stall when they finally hit cold soil.

Planting onions for a fall harvest in Zone 6b

Yes. Plant onions between September 6 and September 27 in Zone 6b, roughly 6 to 3 weeks before the average first frost, so it roots before the ground freezes.

Short-day onion sets planted in fall overwinter in zone 7 and warmer and bulb up months ahead of a spring planting.

Plant from

Sep 6

Plant by

Sep 27

Overwinters, harvest in spring

Spring

Fall dates are counted backward from the Zone 6b average first frost, not forward from a sowing date. See the fall planting calendar by zone for the full method.

Spring vs fall onions in Zone 6b

Planting	Sow or start	In the ground	Harvest
Spring	Feb 4	Apr 1	Jul 10
Fall	by Sep 27	Sep 27	Next spring

Last spring frost

Apr 15

First fall frost

Oct 18

Growing season

186 days

Onions in nearby zones

Onions in Zone 6a (colder) Onions in Zone 7a (warmer) Full Onions grow guide Zone 6b planting calendar

Other crops in Zone 6b

Tomatoes in Zone 6b Peppers in Zone 6b Cucumbers in Zone 6b Lettuce in Zone 6b Zucchini in Zone 6b Carrots in Zone 6b Beans (bush) in Zone 6b Peas in Zone 6b Broccoli in Zone 6b Spinach in Zone 6b Kale in Zone 6b Garlic in Zone 6b Potatoes in Zone 6b Squash (winter) in Zone 6b Corn in Zone 6b Radishes in Zone 6b Beets in Zone 6b Eggplant in Zone 6b Basil in Zone 6b Cilantro in Zone 6b Parsley in Zone 6b Pumpkins in Zone 6b Sunflowers in Zone 6b

Frequently asked questions

When should I start onions in Zone 6b?

Start onions seeds indoors around Feb 4 (Zone 6b).

Can I direct sow onions in Zone 6b?

Onions is best started indoors and transplanted in Zone 6b rather than direct sown.

Can I plant onions in the fall in Zone 6b?