When to Plant Dahlia in Washington

Growing Dahlia in Washington: Complete Guide

Dahlia (Dahlia pinnata) is a warm-season crop that needs a head start indoors before Washington's last frost. Most Washington gardeners begin seeds indoors around Saturday, January 9, 2027 and move transplants outside around Saturday, February 27, 2027, after the risk of frost has passed.

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 90 days to maturity, Dahlia needs the indoor head start that Washington's growing season requires. Starting indoors ensures you have strong transplants ready the moment outdoor conditions are right.

Dahlia requires full sun (6-8 hours) and regular (1-2 inches/week) 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.