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Montana on the 2023 USDA hardiness map

Montana Planting Zones by City and ZIP Code

Montana runs from zones 3b to 6b; 32% of its ZIPs are 4b, Billings is 5a and Missoula is 5b.

399 ZIP codes

Montana runs from zones 3b to 6b

The coldest night of the winter averages -35°F to -30°F in the coldest of Montana’s ZIP codes and -5°F to 0°F in the warmest. Most of the state is zone 4b.

  • 3b6% of ZIPs (25), -35°F to -30°F
  • 4a18% of ZIPs (71), -30°F to -25°F
  • 4b32% of ZIPs (129), -25°F to -20°F
  • 5a28% of ZIPs (111), -20°F to -15°F
  • 5b8% of ZIPs (32), -15°F to -10°F
  • 6a8% of ZIPs (30), -10°F to -5°F
  • 6bunder 1% of ZIPs (1), -5°F to 0°F

Planting zones of Montana cities

CityZoneColdest night, on averageSince 2012
Billings591015a-20°F to -15°Fhalf a zone warmer than 2012 (4b)
Missoula598025b-15°F to -10°Fsame as 2012
Great Falls594014b-25°F to -20°Fhalf a zone warmer than 2012 (4a)
Bozeman597155a-20°F to -15°Fhalf a zone warmer than 2012 (4b)
Helena596014b-25°F to -20°Fsame as 2012
Kalispell599015b-15°F to -10°Fhalf a zone warmer than 2012 (5a)

Tap a ZIP for that address’s frost dates and this month’s jobs.

Your address

Find your zone anywhere in Montana

A ZIP code or a town gives you its zone, how it moved since 2012, the frost dates at the nearest NOAA station, and the jobs for this month timed from them.

Month by month

What to plant in Montana this month

The calendar for each of Montana's main zones, from vegetables to pruning and winter protection, each job tied to the extension page it comes from. Pick a month, or read the whole year below it.

Timed from the median frost dates of the 32 NOAA stations in Montana’s zone 4b: last spring frost May 22, first fall frost Sep 23. Your own ZIP’s frost dates move every window, so the ZIP tool times them for you.

Pick a month above to see every job in it.

The year at a glance

  1. Start vegetable seeds indoorsFeb to May
  2. Sow vegetables in the gardenApr to May
  3. Sow the fall vegetable gardenJun to Jul
  4. Set out transplantsApr to Jun
  5. Plant trees and shrubsApr 10 to Jun 5 and Sep 9 to Oct 28
  6. Plant garlicSep 9 to Oct 14
  7. Plant tulips and other spring bulbsSep 30 to Oct 7
  8. Divide fall-blooming perennialsMay 1 to Jun 12
  9. Divide spring and summer-blooming perennialsAug 12 to Sep 23
  10. Prune trees and summer-flowering shrubs while dormantMar 13 to Apr 24
  11. Prune spring-flowering shrubs after they bloomMay 8 to Jul 3
  12. Water evergreens and new plantings until the ground freezesAug 26 to Nov 4
  13. Mulch perennial crowns once the ground freezesNov 4 to Nov 18
  14. Pull back the winter mulchApr 3 to Apr 17
  15. Put hardware cloth around young tree trunksSep 23 to Nov 4
  16. Dig and store canna, dahlia and gladiolusSep 23 to Sep 30
  17. Cut back perennials after a hard freezeSep 30 to Oct 28
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What changed in Montana since 2012

Every ZIP on both maps
57%
ZIP codes now warmer
229 of 399 moved up at least half a zone
166
In the same half zone
unchanged since 2012
19
A full zone warmer
moved up two half zones
4
Colder than 2012
moved down at least half a zone

Compared ZIP by ZIP from the 2023 and 2012 USDA tables; 399 Montana ZIP codes appear in both.

The 2023 map

Why Montana’s zones moved

Of the cities above, Billings went from 4b to 5a, Great Falls went from 4a to 4b, Bozeman went from 4b to 5a and Kalispell went from 5a to 5b.

The USDA explains the national picture: “When compared to the 2012 map, the 2023 version reveals that about half of the country shifted to the next warmer half zone, and the other half of the country remained in the same half zone.” The new map uses 1991 to 2020 and more than 13,000 weather stations, so it draws Montana’s hills, valleys and cities more finely than the 2012 map did.

A warmer zone changes which perennials and shrubs come through the winter, not when the garden gets planted; that still follows the frost dates.

A hand pressing a single garlic clove into loose, freshly tilled brown soil
Garlic goes in around the first fall frost, from about two weeks before it to three weeks after, so the cloves root before the ground freezes. Hardneck types suit a cold winter and softneck types a mild one. “Planting the Garlic” by Dwight Sipler from Stow, MA, USA, CC BY 2.0
Montana gardening

Frost dates and seed starting in Montana

Seed starting calendar for MontanaWhen to start each vegetable indoors, from the frost at your nearest station.First frost in MontanaWhen the first fall frost usually arrives across Montana.Frost dates by ZIPYour last spring and first fall frost, with the odds either side.Lawn care calendar for MontanaWhen to seed, feed and overseed the lawn.When to plant garlicThe fall planting window by ZIP.When to plant tulip bulbsOnce the soil cools, timed to your first frost.
Questions

Montana planting zone questions

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Other states

Planting zones by state

Maine: zones 3b to 7a, mostly 5aME5aNew Hampshire: zones 4a to 6b, mostly 6aNH6aVermont: zones 4a to 6a, mostly 5aVT5aMassachusetts: zones 5b to 7b, mostly 6bMA6bConnecticut: zones 6a to 7b, mostly 6bCT6bRhode Island: zones 6b to 7b, mostly 7aRI7aNew York: zones 4a to 7b, mostly 6aNY6aNew Jersey: zones 6b to 8a, mostly 7aNJ7aPennsylvania: zones 5b to 8a, mostly 6bPA6bDelaware: zones 7a to 8a, mostly 7bDE7bMaryland: zones 6a to 8a, mostly 7bMD7bVirginia: zones 6a to 8b, mostly 7bVA7bWest Virginia: zones 5b to 7a, mostly 7aWV7aNorth Carolina: zones 6b to 9a, mostly 8aNC8aSouth Carolina: zones 8a to 9b, mostly 8bSC8bGeorgia: zones 7a to 9a, mostly 8aGA8aFlorida: zones 8b to 11b, mostly 10aFL10aAlabama: zones 7b to 9b, mostly 8bAL8bTennessee: zones 6b to 8a, mostly 7bTN7bKentucky: zones 6b to 7b, mostly 7aKY7aOhio: zones 6a to 7a, mostly 6bOH6bIndiana: zones 5b to 7a, mostly 6aIN6aIllinois: zones 5a to 7a, mostly 6aIL6aMichigan: zones 4a to 7a, mostly 6aMI6aWisconsin: zones 3b to 6a, mostly 5bWI5bMinnesota: zones 3a to 5a, mostly 4bMN4bMississippi: zones 7b to 9a, mostly 8bMS8bLouisiana: zones 8b to 10a, mostly 9aLA9aArkansas: zones 7a to 8b, mostly 8aAR8aTexas: zones 6b to 10b, mostly 8bTX8bOklahoma: zones 6b to 8a, mostly 7bOK7bMissouri: zones 5b to 8a, mostly 6bMO6bIowa: zones 4b to 6a, mostly 5aIA5aKansas: zones 6a to 7a, mostly 6bKS6bNebraska: zones 5a to 6a, mostly 5bNE5bSouth Dakota: zones 4a to 5b, mostly 4bSD4bNorth Dakota: zones 3b to 4b, mostly 4aND4aMontana: zones 3b to 6b, mostly 4bMT4bWyoming: zones 4a to 5b, mostly 5aWY5aColorado: zones 4a to 7a, mostly 6aCO6aNew Mexico: zones 5a to 8b, mostly 7bNM7bWashington: zones 6a to 9b, mostly 8bWA8bOregon: zones 5b to 9b, mostly 8bOR8bCalifornia: zones 5b to 11a, mostly 9bCA9bIdaho: zones 4a to 7b, mostly 6bID6bUtah: zones 4a to 8b, mostly 6aUT6aNevada: zones 5a to 10a, mostly 9bNV9bArizona: zones 5b to 10a, mostly 9bAZ9bAlaska: zones 1a to 8b, mostly 5aAK5aHawaii: zones 10b to 13a, mostly 12bHI12b
Each state is colored by the zone most of its ZIP codes are in; the state page has the full range. Tap a state.

Sources. USDA Plant Hardiness Zone Map, ZIP code tables (2023 and 2012), PRISM Climate Group, Oregon State University; USDA Plant Hardiness Zone Map; USDA Unveils Updated Plant Hardiness Zone Map (USDA Agricultural Research Service, November 15, 2023); NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal, by station (v1.0.1); NC State Extension Gardener Plant Toolbox. Zones are read from the PRISM ZIP code tables, read Oct 9, 2026; a ZIP code’s zone is the zone at its center. The calendar’s extension sources are listed on the planting zones page and under each job.