When to plant Sweet corn in District of Columbia

In spring, Mar 25 – May 15 in Washington.

In fall, June 1 – Aug 15 in Washington.

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

Sweet corn planting dates by place in District of Columbia
PlaceSpringFall
WashingtonMar 25 – May 15June 1 – Aug 15

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 corn.