Plant Zucchini in Zone 6b

Zone 6b averages 186 frost-free days, running from a last spring frost around April 15 to a first fall frost around October 18. Zucchini needs roughly 55 days from planting out to first harvest, so it uses about 30 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 Mar 25, about 3 weeks ahead of the Zone 6b last frost. Transplants go out around Apr 29. Starting earlier than that in Zone 6b usually backfires: plants outgrow their cells and stall when they finally hit cold soil. At 55 days to harvest, a 186-day Zone 6b season has room for about 2 sowings, so stagger them rather than planting everything at once.

Yes. Sow zucchini by July 27 in Zone 6b. 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.