When to Plant Zucchini

Planting time for zucchini is set by your frost dates, not by the calendar month. Start seeds indoors about 3 weeks before your last spring frost, then transplant about 2 weeks after it. From there it takes roughly 55 days to the first harvest. Zucchini is a tender crop, and a single light frost ends it, so both ends of its season are hard boundaries. Pick your zone below for exact dates, or find your zone by ZIP if you are not sure which one you are in.

One midsummer sowing of zucchini replaces the spring plants right as squash vine borer takes them out. Because it is a tender crop, the fall sowing has to finish before the first frost with no margin for error, so the sow-by dates in the table above are hard deadlines rather than suggestions.

Fall dates are counted backward from your first frost, not forward from a sowing date. Take the 55 days zucchini needs, add about two weeks because growth slows once days shorten after the equinox, then add two more weeks of margin because frost kills it outright. That is 83 days before your first frost. The coldest zone where this still works on the averages is Zone 4a.

For the whole-garden version of this arithmetic, see the fall planting calendar by zone, and how to read and stretch your first frost date.

Zucchini grows well next to corn, beans (bush) and radishes. Keep it away from potatoes. A sprawling cucurbit that crowds out anything else competing for the same ground. The full grid for all 24 crops is in the companion planting chart.