Fall in zone 6aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 59873 (Belknap, MT)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Thompson Falls Ph, MT (6 miles away).
- Average last spring frostMay 750% chance of a 32°F freeze after this date
- Average first fall frostOct 450% chance of a 32°F freeze by this date
- Growing season (frost-free)150 daysmedian, 32°F threshold
- USDA hardiness zone6a-10 to -5°F avg. coldest night
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This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
No soil station with a fresh reading within 62 miles.
4-inch depth
No soil station with a fresh reading within 62 miles.
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 59873 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
No soil reading near this ZIP. Typical extension timing for your region: spring mid-April to mid-May.
Fertilizer window
Lawn region: Mountain West and High Plains. Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Apr 25 |
| 50% (the "average" last frost) | May 7 |
| 10% (cautious: only 1 year in 10 freezes later) | May 19 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Sep 21 |
| 50% (the "average" first frost) | Oct 4 |
| 90% (late: most years have frozen by now) | Oct 19 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 22 | Sep 21 |
| 32°F (freeze) | May 7 | Oct 4 |
| 28°F (hard freeze) | Apr 22 | Oct 18 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 59873
Dates count from your average last spring frost (May 7) and first fall frost (Oct 4). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Mar 12–26 | May 14–28 (transplant) | – |
| Pepper (sweet and hot) | Feb 26–Mar 12 | May 21–Jun 4 (transplant) | – |
| Eggplant | Feb 26–Mar 12 | May 21–Jun 4 (transplant) | – |
| Tomatillo | Mar 12–26 | May 14–28 (transplant) | – |
| Lettuce | Mar 12–26 | Apr 16–May 7 (transplant) Apr 9–May 21 (sow outdoors) | Aug 9–30 (transplant) Jul 26–Aug 23 (sowing) |
| Spinach | – | Mar 26–Apr 16 (sow outdoors) | Aug 9–30 (sowing) |
| Kale | Mar 12–26 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | Jul 12–Aug 9 (transplant) Jun 28–Jul 26 (sowing) |
| Collards | Mar 12–26 | Apr 9–May 7 (transplant) Apr 9–May 7 (sow outdoors) | Jul 12–Aug 9 (transplant) Jun 28–Jul 26 (sowing) |
| Broccoli | Feb 26–Mar 12 | Apr 9–23 (transplant) | Jun 28–Jul 26 (transplant) |
| Cabbage | Feb 26–Mar 12 | Apr 9–23 (transplant) | Jun 28–Jul 26 (transplant) |
| Cauliflower | Feb 26–Mar 12 | Apr 23–May 7 (transplant) | Jun 28–Jul 26 (transplant) |
| Brussels sprouts | Feb 12–26 | Apr 9–23 (transplant) | Jun 14–Jul 5 (transplant) |
| Kohlrabi | Mar 12–26 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Bok choy / Asian greens | – | Apr 9–23 (sow outdoors) | Aug 9–23 (sowing) |
| Arugula | – | Apr 9–May 7 (sow outdoors) | Aug 9–Sep 6 (sowing) |
| Mustard greens | – | Apr 9–30 (sow outdoors) | Aug 9–23 (sowing) |
| Swiss chard | Mar 26–Apr 9 | Apr 23–May 14 (transplant) Apr 23–May 21 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Beet | – | Apr 9–May 7 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Carrot | – | Apr 16–May 14 (sow outdoors) | Jul 12–26 (sowing) |
| Radish | – | Apr 2–May 14 (sow outdoors) | Aug 23–Sep 6 (sowing) |
| Turnip | – | Apr 9–30 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Parsnip | – | Apr 16–May 7 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 12–Apr 9 (sow outdoors) | Jul 12–26 (sowing) |
| Onion (bulbing) | Feb 12–26 | Mar 26–Apr 9 (transplant) | – |
| Green onion / scallion | – | Mar 26–Apr 23 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Leek | Feb 12–26 | Apr 9–23 (transplant) | – |
| Garlic | – | – | Aug 23–Sep 20 (sowing) |
| Shallot | – | Mar 26–Apr 9 (transplant) | Aug 23–Sep 20 (sowing) |
| Potato | – | Apr 9–23 (transplant) | Jun 14–28 (transplant) |
| Sweet potato | – | May 28–Jun 11 (transplant) | – |
| Sweet corn | – | May 14–28 (sow outdoors) | – |
| Bean, bush (snap) | – | May 14–28 (sow outdoors) | – |
| Bean, pole | – | May 14–28 (sow outdoors) | – |
| Lima bean | – | May 21–Jun 4 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 28–Jun 18 (sow outdoors) | – |
| Cucumber | Apr 9–16 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Summer squash / zucchini | Apr 9–16 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Winter squash | Apr 9–16 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Pumpkin | – | May 14–28 (sow outdoors) | – |
| Watermelon | Apr 9–16 | May 21–Jun 4 (transplant) May 21–Jun 4 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 9–16 | May 21–Jun 4 (transplant) May 21–Jun 4 (sow outdoors) | – |
| Okra | Mar 26–Apr 9 | May 21–Jun 4 (transplant) May 21–Jun 4 (sow outdoors) | – |
| Celery | Feb 12–26 | May 14–21 (transplant) | – |
| Basil | Mar 26–Apr 9 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Cilantro | – | Apr 23–May 21 (sow outdoors) | Aug 9–23 (sowing) |
| Parsley | Feb 26–Mar 12 | Apr 23–May 7 (transplant) Apr 16–May 7 (sow outdoors) | – |
| Dill | – | May 7–21 (sow outdoors) | Aug 9–23 (sowing) |
| Sunflower | – | May 7–21 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 9–23 (transplant) | – |
| Rhubarb (crowns) | – | Apr 9–23 (transplant) | – |
| Strawberry (plants) | – | Apr 9–23 (transplant) | Jul 26–Aug 23 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Thompson Falls Ph, MT (NOAA GHCN-Daily ID USC00248211), elevation 2,380 ft, 6.3 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Trout Creek Rs, MT | 22 mi | May 20 | Sep 21 |
| Mullan Pass Vor/dme, ID | 22 mi | Jun 10 | Sep 23 |
| Mullan, ID | 29 mi | May 12 | Sep 30 |
The average last-frost dates of these stations span 34 days, a rough guide to local variation. See data sources & methods.
Frost questions for 59873
When is the last frost in 59873?
The average (50% chance) last spring freeze of 32°F for ZIP 59873 is May 7. For a more cautious planting date, use May 19, when only 1 year in 10 still sees a later freeze.
When is the first frost in 59873?
The average first fall freeze is October 4. In 1 year in 10 it comes by September 21.
What hardiness zone is 59873?
ZIP 59873 is in USDA zone 6a (-10 to -5°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 59873 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
59830 De Borgia 59874 Trout Creek 59867 Saltese 59866 St. Regis 59842 Haugan 59859 Weeksville 83846 Mullan 83874
Other ZIP codes in Sanders County
59831 59844 59845 59848 59853 59856 59859 59874 All Sanders County frost dates · Montana frost dates
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Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
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- Weekly yard to-dos
Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.