When to plant Lettuce in New Hampshire

In spring, from Apr 1 – June 1 in Dover to Apr 15 – June 15 in Lebanon.

In fall, from June 1 – Aug 1 in Claremont to July 15 – Sept 1 in Somersworth.

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

Leaf lettuce planting dates by place in New Hampshire
PlaceSpringFall
ClaremontApr 15 – June 15June 1 – Aug 1
ConcordApr 15 – June 15June 1 – Aug 1
DoverApr 1 – June 1July 15 – Sept 1
KeeneApr 15 – June 15June 1 – Aug 1
LaconiaApr 1 – June 1July 15 – Sept 1
LebanonApr 15 – June 15July 15 – Sept 1
ManchesterApr 1 – June 1July 15 – Sept 1
NashuaApr 1 – June 1July 15 – Sept 1
PortsmouthApr 1 – June 1July 15 – Sept 1
RochesterApr 1 – June 1July 15 – Sept 1
SomersworthApr 1 – June 1July 15 – Sept 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 leaf lettuce.