Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 06065 — Riverton, CT

ZIP code 06065 (Riverton, Northwest Hills County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 30 and the first fall frost October 17.

Where ZIP 06065 is

Outlined: the ZIP code area · 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

Coldest night−23.3 to −20.6 °C

Last frostApr 30

First frostOct 17

2012 zone5b

Was 5b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Riverton, CT…

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 Riverton, CT

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 30median — 50% chance of a later frost

Safe for tender plantsMay 15only 10% chance of frost after

First fall frostOctober 17median — 10% chance by Oct 4

Growing season168 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 29.

From the NOAA station Barkhamsted, CT — 4 miles away, elevation 709 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 06065

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 19 – Apr 2

SpinachSow outdoors · Mar 19 – Apr 9

Broccoli, cabbageStart indoors · Feb 19 – Mar 5

Broccoli, cabbageTransplant · Apr 9 – Apr 23

Onion setsPlant outdoors · Apr 2 – Apr 16

PotatoesPlant outdoors · Apr 9 – Apr 23

LettuceSow outdoors · Apr 2 – Apr 16

Carrots, beetsSow outdoors · Apr 9 – Apr 23

TomatoesStart indoors · Mar 5 – Mar 19

TomatoesTransplant · May 7 – May 21

Peppers, eggplantStart indoors · Feb 19 – Mar 5

Peppers, eggplantTransplant · May 14 – May 28

BeansSow outdoors · May 7 – May 21

Sweet cornSow outdoors · May 7 – May 21

Cucumbers, squashSow outdoors · May 7 – May 21

Fall lettuce, spinachSow outdoors · Aug 22 – Sep 5

GarlicPlant cloves · Oct 3 – Nov 7

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 17) 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 06065 came on Apr 12 — about the same time as the 1991–2020 average (Apr 14).

average
Apr 142026
Apr 12

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 Connecticut

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

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 Riverton, CT.

Soil in Riverton, CT

The soil mapped at the center of ZIP 06065 is Paxton — moderately decomposed plant material, well drained.

TextureModerately decomposed plant materialtop layer

DrainageWell drainednatural drainage class

Organic matter95%high

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Paxton and Montauk fine sandy loams, 3 to 15 percent slopes, extremely stony.

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 06065; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Riverton, CT

Summer high84 °Faverage high, July

Winter low14 °Faverage low, January

Hot days15days a year at 90 °F or more

Freezing nights151nights a year at 32 °F or less

Growing degree days2,681base 50 °F — the season’s usable heat

Longest day15 h 14 mindaylight on June 21

Shortest day9 h 07 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation52.5 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Barkhamsted, CT (4 mi away); precipitation: Colebrook 1.0 Ne, CT (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

060636a

Barkhamsted, CT · 3 mi

060216a

Colebrook, CT · 4 mi

060916a

West Hartland, CT · 4 mi

060276a

East Hartland, CT · 5 mi

060986a

Winsted, CT · 6 mi

060616a

Pine Meadow, CT · 7 mi

060906a

West Granby, CT · 8 mi

060606a

North Granby, CT · 8 mi

Connecticut planting zones →

Questions about 06065

What planting zone is ZIP code 06065?

ZIP code 06065 (Riverton, CT) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Riverton, CT?

The median last spring frost (32 °F) near 06065 is April 30; after May 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Barkhamsted station.

When is the first frost in Riverton, CT?

The median first fall frost near 06065 is October 17, giving a median frost-free growing season of 168 days.

When should I plant tomatoes in 06065?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 06065 get?

About 52.5 inches of precipitation a year (NOAA 1991–2020 normals, Colebrook 1.0 Ne station).

How hot do summers get in Riverton, CT?

The average high peaks at 84 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 06065 have?

The USDA soil survey maps Paxton at the center of ZIP 06065: moderately decomposed plant material, well drained.

Did spring come early in Riverton, CT in 2026?

Spring leaf-out near 06065 came on Apr 12 in 2026, about the same as the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Riverton, CT?

Long-day onions: the longest day near 06065 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 06065 change?

Yes. The 2012 USDA map put 06065 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.