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

Planting zone for 37640 — Butler, TN

ZIP code 37640 (Butler, Johnson County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 18 and the first fall frost October 24.

Where ZIP 37640 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 18

First frostOct 24

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Butler, TN…

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 Butler, TN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 18median — 50% chance of a later frost

Safe for tender plantsMay 7only 10% chance of frost after

First fall frostOctober 24median — 10% chance by Oct 11

Growing season188 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 4 and returns around November 2.

From the NOAA station Flat Springs 1e, NC — 6 miles away, elevation 3,330 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 37640

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 7 – Mar 21

SpinachSow outdoors · Mar 7 – Mar 28

Broccoli, cabbageStart indoors · Feb 7 – Feb 21

Broccoli, cabbageTransplant · Mar 28 – Apr 11

Onion setsPlant outdoors · Mar 21 – Apr 4

PotatoesPlant outdoors · Mar 28 – Apr 11

LettuceSow outdoors · Mar 21 – Apr 4

Carrots, beetsSow outdoors · Mar 28 – Apr 11

TomatoesStart indoors · Feb 21 – Mar 7

TomatoesTransplant · Apr 25 – May 9

Peppers, eggplantStart indoors · Feb 7 – Feb 21

Peppers, eggplantTransplant · May 2 – May 16

BeansSow outdoors · Apr 25 – May 9

Sweet cornSow outdoors · Apr 25 – May 9

Cucumbers, squashSow outdoors · Apr 25 – May 9

Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12

GarlicPlant cloves · Oct 10 – Nov 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Oct 24) 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 37640 came on Mar 2 — 5 days earlier than the 1991–2020 average (Mar 7).

average
Mar 72026
Mar 2

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 7a in Tennessee

560 plants native to the lower 48 states, recorded in Tennessee, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 Butler, TN.

Soil in Butler, TN

The soil mapped at the center of ZIP 37640 is Bledsoe — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Bledsoe silt loam, 5 to 12 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 37640; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Butler, TN

Summer high79 °Faverage high, July

Winter low24 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights95nights a year at 32 °F or less

Growing degree days2,884base 50 °F — the season’s usable heat

Longest day14 h 38 mindaylight on June 21

Shortest day9 h 41 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation49 inper year, rain and melted snow

Snowfall48 inper year; 32 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Flat Springs 1e, NC (6 mi away); precipitation: Flat Springs 1e, NC (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

286927a

Vilas, NC · 8 mi

376437a

Elizabethton, TN · 9 mi

286797a

Sugar Grove, NC · 9 mi

Zionville, NC · 12 mi

376837a

Mountain City, TN · 12 mi

286046b

Banner Elk, NC · 12 mi

Tennessee planting zones →

Questions about 37640

What planting zone is ZIP code 37640?

ZIP code 37640 (Butler, TN) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Butler, TN?

The median last spring frost (32 °F) near 37640 is April 18; after May 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Flat Springs 1e station.

When is the first frost in Butler, TN?

The median first fall frost near 37640 is October 24, giving a median frost-free growing season of 188 days.

When should I plant tomatoes in 37640?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 37640 get?

About 49 inches of precipitation a year and 48 inches of snowfall (NOAA 1991–2020 normals, Flat Springs 1e station).

How hot do summers get in Butler, TN?

The average high peaks at 79 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 37640 have?

The USDA soil survey maps Bledsoe at the center of ZIP 37640: silt loam, well drained, pH about 6.7 (neutral).

Did spring come early in Butler, TN in 2026?

Spring leaf-out near 37640 came on Mar 2 in 2026, 5 days earlier than the 1991–2020 average (Mar 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Butler, TN?

Intermediate onions: the longest day near 37640 is 14 h 38 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 37640 change?

Yes. The 2012 USDA map put 37640 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.