When to plant Watermelon in District of Columbia

In spring, Apr 10 – May 15 in Washington.

In fall, July 15 – 30 in Washington.

USDA's earliest safe spring and latest safe fall planting dates, matched to each place's average frost dates.

Watermelon planting dates by place in District of Columbia
PlaceSpringFall
WashingtonApr 10 – May 15July 15 – 30

Planting dates: USDA Home and Garden Bulletin No. 9 (1967), tables 4 and 5. Frost dates: NOAA U.S. Climate Normals 1991–2020. “—” means the place's frost date is outside the table. The full USDA table for watermelon.