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

Planting zone for 37377 — Signal Mountain, TN

ZIP code 37377 (Signal Mountain, Hamilton County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is March 26 and the first fall frost November 8.

Where ZIP 37377 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 frostMar 26
First frostNov 8
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 Signal Mountain, 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 Signal Mountain, TN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 26median — 50% chance of a later frost
Safe for tender plantsApril 13only 10% chance of frost after
First fall frostNovember 8median — 10% chance by Oct 25
Growing season228 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 12 and returns around November 24.

From the NOAA station Whitwell-Sequatchie Vly, TN — 8 miles away, elevation 1,020 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 37377

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 12 – Feb 26
SpinachSow outdoors · Feb 12 – Mar 5
Broccoli, cabbageStart indoors · Jan 15 – Jan 29
Broccoli, cabbageTransplant · Mar 5 – Mar 19
Onion setsPlant outdoors · Feb 26 – Mar 12
PotatoesPlant outdoors · Mar 5 – Mar 19
LettuceSow outdoors · Feb 26 – Mar 12
Carrots, beetsSow outdoors · Mar 5 – Mar 19
TomatoesStart indoors · Jan 29 – Feb 12
TomatoesTransplant · Apr 2 – Apr 16
Peppers, eggplantStart indoors · Jan 15 – Jan 29
Peppers, eggplantTransplant · Apr 9 – Apr 23
BeansSow outdoors · Apr 2 – Apr 16
Sweet cornSow outdoors · Apr 2 – Apr 16
Cucumbers, squashSow outdoors · Apr 2 – Apr 16
Fall lettuce, spinachSow outdoors · Sep 13 – Sep 27
GarlicPlant cloves · Oct 25 – Nov 29
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 26) and first fall frost (Nov 8) 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 37377 came on Feb 25 — 5 days earlier than the 1991–2020 average (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 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.

Trees 82

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 116

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 184

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican spongeplant0.5 ft · blooms mid spring · high shade tolerance · to −24 °F

Grasses 157

American cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fbluejoint5 ft · blooms late spring · high shade tolerance · to −33 °F

Vines 14

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °F

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 Signal Mountain, TN.

Soil in Signal Mountain, TN

The soil mapped at the center of ZIP 37377 is Lily — loam, well drained.

TextureLoama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.25%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Lily loam, 6 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 37377; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Signal Mountain, TN

Summer high88 °Faverage high, July
Winter low32 °Faverage low, January
Hot days32days a year at 90 °F or more
Freezing nights63nights a year at 32 °F or less
Growing degree days4,762base 50 °F — the season’s usable heat
Longest day14 h 32 mindaylight on June 21
Shortest day9 h 47 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation62.5 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 49 °F, low 32 °F 49°32° JanFebruary: average high 54 °F, low 35 °F 54°35° FebMarch: average high 63 °F, low 41 °F 63°41° MarApril: average high 72 °F, low 49 °F 72°49° AprMay: average high 78 °F, low 57 °F 78°57° MayJune: average high 84 °F, low 65 °F 84°65° JunJuly: average high 88 °F, low 68 °F 88°68° JulAugust: average high 88 °F, low 67 °F 88°67° AugSeptember: average high 83 °F, low 62 °F 83°62° SepOctober: average high 72 °F, low 50 °F 72°50° OctNovember: average high 61 °F, low 41 °F 61°41° NovDecember: average high 52 °F, low 35 °F 52°35° Dec

Precipitation by month inches

0″2″4″6″January: 5.32 in precipitation 5.3 JanFebruary: 5.29 in precipitation 5.3 FebMarch: 5.74 in precipitation 5.7 MarApril: 5.72 in precipitation 5.7 AprMay: 4.93 in precipitation 4.9 MayJune: 5.52 in precipitation 5.5 JunJuly: 5.26 in precipitation 5.3 JulAugust: 4.55 in precipitation 4.5 AugSeptember: 4.56 in precipitation 4.6 SepOctober: 3.78 in precipitation 3.8 OctNovember: 5.25 in precipitation 5.3 NovDecember: 6.54 in precipitation 6.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Whitwell-Sequatchie Vly, TN (8 mi away); precipitation: Whitwell 4.5 Ene, TN (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

374057b
Chattanooga, TN · 6 mi
374158a
Chattanooga, TN · 8 mi
373847b
Soddy Daisy, TN · 9 mi
373977b
Whitwell, TN · 9 mi
373438a
Hixson, TN · 9 mi
373518a
Lupton City, TN · 10 mi
373797b
Soddy Daisy, TN · 11 mi
374197b
Chattanooga, TN · 12 mi

Tennessee planting zones →

Questions about 37377

What planting zone is ZIP code 37377?

ZIP code 37377 (Signal Mountain, 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 Signal Mountain, TN?

The median last spring frost (32 °F) near 37377 is March 26; after April 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Whitwell-Sequatchie Vly station.

When is the first frost in Signal Mountain, TN?

The median first fall frost near 37377 is November 8, giving a median frost-free growing season of 228 days.

When should I plant tomatoes in 37377?

Start tomato seeds indoors around Jan 29 – Feb 12 and set transplants outside around Apr 2 – Apr 16, one to three weeks after the median last frost.

How much rain and snow does 37377 get?

About 62.5 inches of precipitation a year (NOAA 1991–2020 normals, Whitwell 4.5 Ene station).

How hot do summers get in Signal Mountain, TN?

The average high peaks at 88 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 37377 have?

The USDA soil survey maps Lily at the center of ZIP 37377: loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Signal Mountain, TN in 2026?

Spring leaf-out near 37377 came on Feb 25 in 2026, 5 days earlier than the 1991–2020 average (Mar 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Signal Mountain, TN?

Intermediate onions: the longest day near 37377 is 14 h 32 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 37377 change?

Yes. The 2012 USDA map put 37377 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.