Plant Cucumbers in Zone 4b

Zone 4b averages 146 frost-free days, running from a last spring frost around May 5 to a first fall frost around September 28. Cucumbers needs roughly 60 days from planting out to first harvest, so it uses about 41 percent of that window. Cucumbers is a tender crop, which is what decides where in the window it belongs.

Because cucumbers needs a head start, sow seed indoors around Apr 14, about 3 weeks ahead of the Zone 4b last frost. Transplants go out around May 19. Starting earlier than that in Zone 4b usually backfires: plants outgrow their cells and stall when they finally hit cold soil.

Yes. Sow cucumbers by July 2 in Zone 4b. That is 88 days before the average first frost, which covers the 60 days to maturity plus about two weeks for the slower growth that comes with shortening days, plus a two week margin because frost kills cucumbers outright.

A second sowing in midsummer usually dodges the worst of the cucumber beetle and powdery mildew pressure that kills the spring planting.