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

Planting zone for 37846 — Philadelphia, TN

ZIP code 37846 (Philadelphia, Loudon County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 10 and the first fall frost October 27.

Where ZIP 37846 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 10

First frostOct 27

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 Philadelphia, 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 Philadelphia, TN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 10median — 50% chance of a later frost

Safe for tender plantsApril 28only 10% chance of frost after

First fall frostOctober 27median — 10% chance by Oct 14

Growing season199 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around November 5.

From the NOAA station Decatur 7ne, TN — 11 miles away, elevation 751 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 37846

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 27 – Mar 13

SpinachSow outdoors · Feb 27 – Mar 20

Broccoli, cabbageStart indoors · Jan 30 – Feb 13

Broccoli, cabbageTransplant · Mar 20 – Apr 3

Onion setsPlant outdoors · Mar 13 – Mar 27

PotatoesPlant outdoors · Mar 20 – Apr 3

LettuceSow outdoors · Mar 13 – Mar 27

Carrots, beetsSow outdoors · Mar 20 – Apr 3

TomatoesStart indoors · Feb 13 – Feb 27

TomatoesTransplant · Apr 17 – May 1

Peppers, eggplantStart indoors · Jan 30 – Feb 13

Peppers, eggplantTransplant · Apr 24 – May 8

BeansSow outdoors · Apr 17 – May 1

Sweet cornSow outdoors · Apr 17 – May 1

Cucumbers, squashSow outdoors · Apr 17 – May 1

Fall lettuce, spinachSow outdoors · Sep 1 – Sep 15

GarlicPlant cloves · Oct 13 – Nov 17

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 10) and first fall frost (Oct 27) 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 37846 came on Feb 21 — 4 days earlier than the 1991–2020 average (Feb 25).

average
Feb 252026
Feb 21

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 Philadelphia, TN.

Soil in Philadelphia, TN

The soil mapped at the center of ZIP 37846 is Fullerton — gravelly silt loam, well drained.

TextureGravelly silt loama good balance for most vegetables

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

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Fullerton cherty silt loam, moderately steep phase.

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 37846; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Philadelphia, TN

Summer high89 °Faverage high, July

Winter low28 °Faverage low, January

Hot days46days a year at 90 °F or more

Freezing nights99nights a year at 32 °F or less

Growing degree days4,386base 50 °F — the season’s usable heat

Longest day14 h 35 mindaylight on June 21

Shortest day9 h 44 mindaylight on December 21

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

Precipitation58.8 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: Decatur 7ne, TN (11 mi away); precipitation: Rockwood 11.3 S, TN (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7b.

378747b

Sweetwater, TN · 6 mi

Madisonville, TN · 14 mi

377717b

Lenoir City, TN · 14 mi

377427b

Greenback, TN · 17 mi

Tennessee planting zones →

Questions about 37846

What planting zone is ZIP code 37846?

ZIP code 37846 (Philadelphia, 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 Philadelphia, TN?

The median last spring frost (32 °F) near 37846 is April 10; after April 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Decatur 7ne station.

When is the first frost in Philadelphia, TN?

The median first fall frost near 37846 is October 27, giving a median frost-free growing season of 199 days.

When should I plant tomatoes in 37846?

Start tomato seeds indoors around Feb 13 – Feb 27 and set transplants outside around Apr 17 – May 1, one to three weeks after the median last frost.

How much rain and snow does 37846 get?

About 58.8 inches of precipitation a year (NOAA 1991–2020 normals, Rockwood 11.3 S station).

How hot do summers get in Philadelphia, TN?

The average high peaks at 89 °F in July, with about 46 days a year at 90 °F or more.

What kind of soil does 37846 have?

The USDA soil survey maps Fullerton at the center of ZIP 37846: gravelly silt loam, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Philadelphia, TN in 2026?

Spring leaf-out near 37846 came on Feb 21 in 2026, 4 days earlier than the 1991–2020 average (Feb 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Philadelphia, TN?

Intermediate onions: the longest day near 37846 is 14 h 35 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 37846 change?

Yes. The 2012 USDA map put 37846 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.