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

Planting zone for 37321 — Dayton, TN

ZIP code 37321 (Dayton, Rhea County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 4 and the first fall frost October 31.

Where ZIP 37321 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 4

First frostOct 31

2012 zone7b

Same zone as on the 2012 map. 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 Dayton, 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 Dayton, TN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 4median — 50% chance of a later frost

Safe for tender plantsApril 22only 10% chance of frost after

First fall frostOctober 31median — 10% chance by Oct 19

Growing season208 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 26 and returns around November 10.

From the NOAA station Dayton 2se, TN — 2 miles away, elevation 824 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 37321

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 21 – Mar 7

SpinachSow outdoors · Feb 21 – Mar 14

Broccoli, cabbageStart indoors · Jan 24 – Feb 7

Broccoli, cabbageTransplant · Mar 14 – Mar 28

Onion setsPlant outdoors · Mar 7 – Mar 21

PotatoesPlant outdoors · Mar 14 – Mar 28

LettuceSow outdoors · Mar 7 – Mar 21

Carrots, beetsSow outdoors · Mar 14 – Mar 28

TomatoesStart indoors · Feb 7 – Feb 21

TomatoesTransplant · Apr 11 – Apr 25

Peppers, eggplantStart indoors · Jan 24 – Feb 7

Peppers, eggplantTransplant · Apr 18 – May 2

BeansSow outdoors · Apr 11 – Apr 25

Sweet cornSow outdoors · Apr 11 – Apr 25

Cucumbers, squashSow outdoors · Apr 11 – Apr 25

Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19

GarlicPlant cloves · Oct 17 – Nov 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 4) and first fall frost (Oct 31) 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 37321 came on Feb 21 — 3 days earlier than the 1991–2020 average (Feb 24).

average
Feb 242026
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 Dayton, TN.

Soil in Dayton, TN

The center of ZIP 37321 is mapped as Urban land-Udorthents complex, 2 to 12 percent slopes: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.

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 37321; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dayton, TN

Summer high88 °Faverage high, July

Winter low28 °Faverage low, January

Hot days33days a year at 90 °F or more

Freezing nights72nights a year at 32 °F or less

Growing degree days4,363base 50 °F — the season’s usable heat

Longest day14 h 34 mindaylight on June 21

Shortest day9 h 45 mindaylight on December 21

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

Precipitation58.7 inper year, rain and melted snow

Snowfall2 inper year; 1 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: Dayton 2se, TN (2 mi away); precipitation: Dayton 2se, TN (2 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.

373327b

Evensville, TN · 8 mi

373737b

Sale Creek, TN · 8 mi

373227b

Decatur, TN · 10 mi

373087b

Birchwood, TN · 11 mi

373387b

Graysville, TN · 12 mi

373047b

Bakewell, TN · 13 mi

373367b

Georgetown, TN · 14 mi

373677a

Pikeville, TN · 15 mi

Tennessee planting zones →

Questions about 37321

What planting zone is ZIP code 37321?

ZIP code 37321 (Dayton, 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 Dayton, TN?

The median last spring frost (32 °F) near 37321 is April 4; after April 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dayton 2se station.

When is the first frost in Dayton, TN?

The median first fall frost near 37321 is October 31, giving a median frost-free growing season of 208 days.

When should I plant tomatoes in 37321?

Start tomato seeds indoors around Feb 7 – Feb 21 and set transplants outside around Apr 11 – Apr 25, one to three weeks after the median last frost.

How much rain and snow does 37321 get?

About 58.7 inches of precipitation a year and 2 inches of snowfall (NOAA 1991–2020 normals, Dayton 2se station).

How hot do summers get in Dayton, TN?

The average high peaks at 88 °F in July, with about 33 days a year at 90 °F or more.

Did spring come early in Dayton, TN in 2026?

Spring leaf-out near 37321 came on Feb 21 in 2026, 3 days earlier than the 1991–2020 average (Feb 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dayton, TN?

Intermediate onions: the longest day near 37321 is 14 h 34 min, so day-neutral types bulb best; long-day varieties may not bulb fully.