When to Plant Watermelon in Oregon

Growing Watermelon in Oregon: Complete Guide

Watermelon (Citrullus lanatus) is a warm-season crop that needs a head start indoors before Oregon's last frost. Most Oregon gardeners begin seeds indoors around Sunday, February 15, 2026 and move transplants outside around Sunday, March 29, 2026, after the risk of frost has passed.

Because Oregon 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 80 days to maturity, Watermelon needs the indoor head start that Oregon's growing season requires. Starting indoors ensures you have strong transplants ready the moment outdoor conditions are right.

Watermelon requires full sun (8+ hours) and regular (1-2 inches/week) moisture. Most of Oregon receives adequate sunlight during the growing season, though gardeners in humid eastern regions should watch for fungal issues and ensure good air circulation.

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 Oregon.