When to Plant Rosemary in Washington

Growing Rosemary in Washington: Complete Guide

Rosemary (Salvia rosmarinus) is a warm-season crop that needs a head start indoors before Washington's last frost. Most Washington gardeners begin seeds indoors around Friday, December 12, 2025 and move transplants outside around Friday, March 6, 2026, 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 120 days to maturity, Rosemary 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.

Rosemary requires full sun (6+ hours) and low (drought tolerant) 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.