Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for Groton, MA

Groton, MA is in USDA zone 6a across its 3 ZIP codes. The median last spring frost is April 29 and the first fall frost October 8.

Groton on the zone map

Outlined: its 1 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone6a−10 to −5 °F
ZIP codes3
Last frostApr 29
First frostOct 8
Growing season162 days

6a 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Groton, MA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 29median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 8median — 10% chance by Sep 28
Growing season162 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 20.

From the NOAA station Nashua Cwsu, NH, elevation 180 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Groton

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 18 – Apr 1
SpinachSow outdoors · Mar 18 – Apr 8
Broccoli, cabbageStart indoors · Feb 18 – Mar 4
Broccoli, cabbageTransplant · Apr 8 – Apr 22
Onion setsPlant outdoors · Apr 1 – Apr 15
PotatoesPlant outdoors · Apr 8 – Apr 22
LettuceSow outdoors · Apr 1 – Apr 15
Carrots, beetsSow outdoors · Apr 8 – Apr 22
TomatoesStart indoors · Mar 4 – Mar 18
TomatoesTransplant · May 6 – May 20
Peppers, eggplantStart indoors · Feb 18 – Mar 4
Peppers, eggplantTransplant · May 13 – May 27
BeansSow outdoors · May 6 – May 20
Sweet cornSow outdoors · May 6 – May 20
Cucumbers, squashSow outdoors · May 6 – May 20
Fall lettuce, spinachSow outdoors · Aug 13 – Aug 27
GarlicPlant cloves · Sep 24 – Oct 29
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 29) and first fall frost (Oct 8) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 01470 came on Apr 9 — about the same time as the 1991–2020 average (Apr 11).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 6a in Massachusetts

544 plants native to the lower 48 states, recorded in Massachusetts, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 66

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 109

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 186

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 157

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 8

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Groton, MA.

Soil in Groton, MA

The soil mapped at the center of ZIP 01470 is Charlton — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH5.1strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter8%high
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Charlton fine sandy loam, 3 to 8 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 01470; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Groton, MA

Summer high85 °Faverage high, July
Winter low14 °Faverage low, January
Hot days27days a year at 90 °F or more
Freezing nights149nights a year at 32 °F or less
Growing degree days2,767base 50 °F — the season’s usable heat
Longest day15 h 19 mindaylight on June 21
Shortest day9 h 03 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation46.3 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 35 °F, low 14 °F 35°14° JanFebruary: average high 38 °F, low 16 °F 38°16° FebMarch: average high 45 °F, low 24 °F 45°24° MarApril: average high 58 °F, low 35 °F 58°35° AprMay: average high 69 °F, low 46 °F 69°46° MayJune: average high 79 °F, low 56 °F 79°56° JunJuly: average high 85 °F, low 62 °F 85°62° JulAugust: average high 83 °F, low 60 °F 83°60° AugSeptember: average high 75 °F, low 52 °F 75°52° SepOctober: average high 62 °F, low 39 °F 62°39° OctNovember: average high 51 °F, low 29 °F 51°29° NovDecember: average high 40 °F, low 20 °F 40°20° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.00 in precipitation 3.0 JanFebruary: 3.07 in precipitation 3.1 FebMarch: 4.11 in precipitation 4.1 MarApril: 3.91 in precipitation 3.9 AprMay: 3.63 in precipitation 3.6 MayJune: 4.19 in precipitation 4.2 JunJuly: 3.63 in precipitation 3.6 JulAugust: 3.71 in precipitation 3.7 AugSeptember: 4.15 in precipitation 4.2 SepOctober: 4.66 in precipitation 4.7 OctNovember: 3.74 in precipitation 3.7 NovDecember: 4.45 in precipitation 4.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Nashua Cwsu, NH (10 mi away); precipitation: Nashua Cwsu, NH (10 mi away). Daylight is calculated from latitude.

ZIP codes in Groton

014506a
−10 to −5 °F
014706a
−10 to −5 °F
014716a
−10 to −5 °F

Massachusetts planting zones →

Questions about Groton

What planting zone is Groton, MA?

Groton, MA is in USDA hardiness zone 6a on the 2023 map (6a: −10 to −5 °F).

When is the last frost in Groton, MA?

The median last spring frost is April 29 and the median first fall frost is October 8 (NOAA 1991–2020 normals, Nashua Cwsu station).

When can I plant a garden in Groton, MA?

Cool-season crops like peas and spinach go in around Mar 18 – Apr 8; tomatoes, peppers, beans and squash after about May 6, once frost risk has passed.

What kind of onions grow in Groton, MA?

Long-day onions: the longest day is 15 h 19 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Groton, MA get?

About 46.3 inches of precipitation a year (NOAA 1991–2020 normals).