When to Plant Cosmos in Washington

Growing Cosmos in Washington: Complete Guide

Cosmos (Cosmos bipinnatus) is a crop that grows best when sown directly in the garden. In Washington, the right time to direct sow is around Friday, February 20, 2026, once soil temperatures are consistently warm enough for germination.

Because Washington stretches across 9 USDA hardiness zones (5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b), planting windows can shift by as much as six to eight weeks from one end of the state to the other. Gardeners in the warmer southern zones can start earlier, while those in cooler northern zones should wait until the zone table above shows their last frost has passed.

With 60 days to maturity, Cosmos fits comfortably within Washington's growing season in most zones. In the warmest parts of the state, a second planting later in the season may be possible.

Cosmos requires full sun (6-8 hours) and low-moderate moisture. The Pacific Northwest's cool, wet springs delay soil warm-up; raised beds and black plastic mulch help jump-start the season.

For the most precise planting dates tailored to your exact location, enter your ZIP code on our planting calendar or use the zone table above to find the schedule for your area of Washington.