Plant Zucchini in Zone 4a
Seed-starting, transplant & harvest dates for USDA Zone 4a
Zone 4a averages 135 frost-free days, running from a last spring frost around May 10 to a first fall frost around September 22. Zucchini needs roughly 55 days from planting out to first harvest, so it uses about 41 percent of that window. Zucchini is a tender crop, which is what decides where in the window it belongs.
Because zucchini needs a head start, sow seed indoors around Apr 19, about 3 weeks ahead of the Zone 4a last frost. Transplants go out around May 24. Starting earlier than that in Zone 4a usually backfires: plants outgrow their cells and stall when they finally hit cold soil.
Planting zucchini for a fall harvest in Zone 4a
Yes. Sow zucchini by July 1 in Zone 4a. That is 83 days before the average first frost, which covers the 55 days to maturity plus about two weeks for the slower growth that comes with shortening days, plus a two week margin because frost kills zucchini outright.
One midsummer sowing of zucchini replaces the spring plants right as squash vine borer takes them out.
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 zucchini in Zone 4a
| Planting | Sow or start | In the ground | Harvest |
|---|---|---|---|
| Spring | Apr 19 | May 24 | Jul 18 |
| Fall | by Jul 1 | Jul 1 | Aug 25 |
Zucchini in nearby zones
Further reading on zucchini
- When to start seeds indoors by zone
Indoor start dates for zucchini, counted back from your last frost.
- Hardening off seedlings: a schedule
A day by day plan for moving zucchini seedlings outdoors.
- Best grow lights for seed starting
What light seedlings actually need, and which fixtures deliver it.
Other crops in Zone 4a
Frequently asked questions
When should I start zucchini in Zone 4a?
Start zucchini seeds indoors around Apr 19 (Zone 4a).
Can I direct sow zucchini in Zone 4a?
Yes, direct sow around May 24.
Can I plant zucchini in the fall in Zone 4a?
Yes. Sow zucchini by July 1 in Zone 4a. That is 83 days before the average first frost, which covers the 55 days to maturity plus about two weeks for the slower growth that comes with shortening days, plus a two week margin because frost kills zucchini outright.
Will zucchini survive frost in Zone 4a?
No. Zucchini is a tender crop and a single light frost ends it, so every Zone 4a planting has to finish before the average first frost.