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

Planting zone for 38343 — Humboldt, TN

ZIP code 38343 (Humboldt, Gibson 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 30.

Where ZIP 38343 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 30

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 Humboldt, 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 Humboldt, 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 21only 10% chance of frost after

First fall frostOctober 30median — 10% chance by Oct 18

Growing season208 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 24 and returns around November 8.

From the NOAA station Jackson 4 Ne, TN — 10 miles away, elevation 430 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 38343

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 4 – Sep 18

GarlicPlant cloves · Oct 16 – Nov 20

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 4) and first fall frost (Oct 30) 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 38343 came on Feb 20 — 4 days earlier than the 1991–2020 average (Feb 24).

average
Feb 242026
Feb 20

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 Humboldt, TN.

Soil in Humboldt, TN

The soil mapped at the center of ZIP 38343 is Routon — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables

pH5.5moderately acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter1.25%low — add compost

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Routon silt loam, 0 to 2 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 38343; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Humboldt, TN

Summer high90 °Faverage high, July

Winter low28 °Faverage low, January

Hot days66days a year at 90 °F or more

Freezing nights79nights a year at 32 °F or less

Growing degree days4,765base 50 °F — the season’s usable heat

Longest day14 h 35 mindaylight on June 21

Shortest day9 h 43 mindaylight on December 21

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

Precipitation55.2 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: Jackson 4 Ne, TN (10 mi away); precipitation: Gadsden 4.9 Sse, TN (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7b.

Tennessee planting zones →

Questions about 38343

What planting zone is ZIP code 38343?

ZIP code 38343 (Humboldt, 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 Humboldt, TN?

The median last spring frost (32 °F) near 38343 is April 4; after April 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Jackson 4 Ne station.

When is the first frost in Humboldt, TN?

The median first fall frost near 38343 is October 30, giving a median frost-free growing season of 208 days.

When should I plant tomatoes in 38343?

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 38343 get?

About 55.2 inches of precipitation a year (NOAA 1991–2020 normals, Gadsden 4.9 Sse station).

How hot do summers get in Humboldt, TN?

The average high peaks at 90 °F in July, with about 66 days a year at 90 °F or more.

What kind of soil does 38343 have?

The USDA soil survey maps Routon at the center of ZIP 38343: silt loam, poorly drained, pH about 5.5 (moderately acidic).

Did spring come early in Humboldt, TN in 2026?

Spring leaf-out near 38343 came on Feb 20 in 2026, 4 days earlier than the 1991–2020 average (Feb 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Humboldt, TN?

Intermediate onions: the longest day near 38343 is 14 h 35 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 38343 change?

Yes. The 2012 USDA map put 38343 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.