GrowZone

Crop by USDA zone

When to plant watermelon in zone 6a

In USDA zone 6a, plant watermelon around May 19, after the representative last frost near May 5. Start seeds indoors around Apr 14.

This page summarizes the supported ZIPs in zone 6a. Your exact city can move earlier or later, so use the ZIP lookup for the frost-station-specific answer.

Get exact watermelon dates by ZIP code.

Seed starting schedule

Watermelon dates for Denver, CO

StepDateHow to use it
Start IndoorsApril 14, 2026Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsMay 19, 2026Move hardened-off seedlings outside after the frost-risk window.
Direct SowMay 19, 2026Sow seed outside when the crop and soil can handle the window.
Milwaukee, WI · Zone 6a Watermelon May 24 Open ZIP-specific answer · last frost May 10 Chicago, IL · Zone 6a Watermelon May 9 Open ZIP-specific answer · last frost Apr 25 Omaha, NE · Zone 6a Watermelon May 19 Open ZIP-specific answer · last frost May 5 Aurora, CO · Zone 6a Watermelon May 19 Open ZIP-specific answer · last frost May 5 Denver, CO · Zone 6a Watermelon May 19 Open ZIP-specific answer · last frost May 5 Colorado Springs, CO · Zone 6a Watermelon May 29 Open ZIP-specific answer · last frost May 15