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

Planting zone for 37686 — Piney Flats, TN

ZIP code 37686 (Piney Flats, Sullivan County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 16 and the first fall frost October 24.

Where ZIP 37686 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.

Zone7b5 to 10 °F

Coldest night−15 to −12.2 °C

Last frostApr 16

First frostOct 24

2012 zone7a

Was 7a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Piney Flats, 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 Piney Flats, TN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 16median — 50% chance of a later frost

Safe for tender plantsMay 5only 10% chance of frost after

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

Growing season190 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 1 and returns around November 1.

From the NOAA station Bristol Tri City Airport, TN — 4 miles away, elevation 1,499 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 37686

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 5 – Mar 19

SpinachSow outdoors · Mar 5 – Mar 26

Broccoli, cabbageStart indoors · Feb 5 – Feb 19

Broccoli, cabbageTransplant · Mar 26 – Apr 9

Onion setsPlant outdoors · Mar 19 – Apr 2

PotatoesPlant outdoors · Mar 26 – Apr 9

LettuceSow outdoors · Mar 19 – Apr 2

Carrots, beetsSow outdoors · Mar 26 – Apr 9

TomatoesStart indoors · Feb 19 – Mar 5

TomatoesTransplant · Apr 23 – May 7

Peppers, eggplantStart indoors · Feb 5 – Feb 19

Peppers, eggplantTransplant · Apr 30 – May 14

BeansSow outdoors · Apr 23 – May 7

Sweet cornSow outdoors · Apr 23 – May 7

Cucumbers, squashSow outdoors · Apr 23 – May 7

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 16) 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 37686 came on Mar 1 — about the same time as the 1991–2020 average (Mar 2).

average
Mar 22026
Mar 1

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 7b in Tennessee

566 plants native to the lower 48 states, recorded in Tennessee, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. 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 Piney Flats, TN.

Soil in Piney Flats, TN

The soil mapped at the center of ZIP 37686 is Collegedale — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

pH5.0strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Collegedale-Etowah complex, 12 to 20 percent slopes, severely eroded.

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 37686; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Piney Flats, TN

Summer high86 °Faverage high, July

Winter low26 °Faverage low, January

Hot days23days a year at 90 °F or more

Freezing nights94nights a year at 32 °F or less

Growing degree days3,903base 50 °F — the season’s usable heat

Longest day14 h 39 mindaylight on June 21

Shortest day9 h 40 mindaylight on December 21

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

Precipitation44 inper year, rain and melted snow

Snowfall9 inper year; 7 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: Bristol Tri City Airport, TN (4 mi away); precipitation: Bristol Tri City Airport, TN (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

376997b

Piney Flats, TN · 3 mi

376947b

Watauga, TN · 6 mi

376177b

Blountville, TN · 6 mi

376217a

Bristol, TN · 6 mi

376157b

Johnson City, TN · 6 mi

376017b

Johnson City, TN · 7 mi

376187b

Bluff City, TN · 8 mi

376637b

Kingsport, TN · 8 mi

All 2 ZIP codes in Piney Flats → · Tennessee planting zones →

Questions about 37686

What planting zone is ZIP code 37686?

ZIP code 37686 (Piney Flats, TN) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Piney Flats, TN?

The median last spring frost (32 °F) near 37686 is April 16; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bristol Tri City Airport station.

When is the first frost in Piney Flats, TN?

The median first fall frost near 37686 is October 24, giving a median frost-free growing season of 190 days.

When should I plant tomatoes in 37686?

Start tomato seeds indoors around Feb 19 – Mar 5 and set transplants outside around Apr 23 – May 7, one to three weeks after the median last frost.

How much rain and snow does 37686 get?

About 44 inches of precipitation a year and 9 inches of snowfall (NOAA 1991–2020 normals, Bristol Tri City Airport station).

How hot do summers get in Piney Flats, TN?

The average high peaks at 86 °F in July, with about 23 days a year at 90 °F or more.

What kind of soil does 37686 have?

The USDA soil survey maps Collegedale at the center of ZIP 37686: silty clay loam, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Piney Flats, TN in 2026?

Spring leaf-out near 37686 came on Mar 1 in 2026, about the same as the 1991–2020 average (Mar 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Piney Flats, TN?

Intermediate onions: the longest day near 37686 is 14 h 39 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 37686 change?

Yes. The 2012 USDA map put 37686 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.