When to Plant Butternut Squash in Washington

Growing Butternut Squash in Washington: Complete Guide

Butternut Squash (Cucurbita moschata) is a warm-season crop that needs a head start indoors before Washington's last frost. Depending on your zone, Washington gardeners start seeds indoors between January 13, 2027 (Zone 9b) and March 28, 2027 (Zone 5b), then move transplants outside once their zone's last frost has passed — the zone table above has your exact dates.

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 100 days to maturity, Butternut Squash 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.

Butternut Squash requires full sun (6-8 hours) and regular (1 inch/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.