GrowZone

Crop by USDA zone

When to plant lettuce in zone 6a

In USDA zone 6a, plant lettuce around Apr 21, after the representative last frost near May 5. Start seeds indoors around Apr 7.

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 lettuce dates by ZIP code.

Seed starting schedule

Lettuce dates for Denver, CO

StepDateHow to use it
Start IndoorsApril 7, 2026Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsApril 21, 2026Move hardened-off seedlings outside after the frost-risk window.
Direct SowApril 21, 2026Sow seed outside when the crop and soil can handle the window.
Milwaukee, WI · Zone 6a Lettuce Apr 26 Open ZIP-specific answer · last frost May 10 Chicago, IL · Zone 6a Lettuce Apr 11 Open ZIP-specific answer · last frost Apr 25 Omaha, NE · Zone 6a Lettuce Apr 21 Open ZIP-specific answer · last frost May 5 Aurora, CO · Zone 6a Lettuce Apr 21 Open ZIP-specific answer · last frost May 5 Denver, CO · Zone 6a Lettuce Apr 21 Open ZIP-specific answer · last frost May 5 Colorado Springs, CO · Zone 6a Lettuce May 1 Open ZIP-specific answer · last frost May 15