When to plant Sweet potatoes in District of Columbia

In spring, Apr 20 – June 1 in Washington.

In fall, June 1 – July 1 in Washington.

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

Sweet potatoes planting dates by place in District of Columbia
PlaceSpringFall
WashingtonApr 20 – June 1June 1 – July 1

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 sweet potatoes.