Hartford, Connecticut: freeze dates & growing season

Three different things get called “Hartford” here, so this page is explicit about all three: the metro label (Hartford), the anchor geography (Census ZCTA 06103, a downtown ZIP-code area), and the climate record (the NOAA station below). Windows are calculated from the station — not from your street address.

Climate basis: NOAA station Hartford Brainard Fld, CT (USW00014752), 2 mi (4 km) from the ZCTA 06103 centroid, elevation 19 ft, on the 1991–2020 climate normals.

Last spring freezeApril 171-in-10 after May 1

First fall freezeOctober 261-in-10 before Oct 12

Frost-free season≈ 191 daysmedian at 32°F

Hard freeze, 28°Apr 3 – Nov 5kills even hardy greens

USDA zone6b-5 to 0°F winter low — not frost timing

The year

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 1

The Hartford year: hatched areas are the freeze-likely seasons in 1991–2020 normals.

What that means in practice

Tomatoes: plant April 24 – May 8
Peas: plant March 6 – March 20
Garlic: plant cloves November 2 – November 9

All 79 crops in Hartford

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

Check a specific ZIP instead

Metro climates vary — elevation, water, and urban heat shift freeze dates by days to weeks. Look up your exact ZIP:

Nearby reviewed metros

Providence, RI · Boston, MA · New York, NY · Manchester, NH · Portland, ME