Fall in zone 6bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 97906 (Harper, OR)
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, Riverside 7 SSW, OR (21 miles away).
- Average last spring frostJun 750% chance of a 32°F freeze after this date
- Average first fall frostSep 650% chance of a 32°F freeze by this date
- Growing season (frost-free)89 daysmedian, 32°F threshold
- USDA hardiness zone6b-5 to 0°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
58°F 55°F or warmer
24-hour average · latest 56°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Jordan Valley Cwma (54 mi), Murphy 10 W (56 mi).
4-inch depth
57°F 55°F or warmer
24-hour average · latest 59°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Jordan Valley Cwma (54 mi), Murphy 10 W (56 mi).
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 97906 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 57°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent (annual bluegrass, winter weeds): window open as soil cools through the 70s and 60s.
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) | May 21 |
| 50% (the "average" last frost) | Jun 7 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 28 |
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) | Aug 22 |
| 50% (the "average" first frost) | Sep 6 |
| 90% (late: most years have frozen by now) | Sep 22 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | n/a | n/a |
| 32°F (freeze) | Jun 7 | Sep 6 |
| 28°F (hard freeze) | May 20 | Sep 19 |
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 97906
Dates count from your average last spring frost (Jun 7) and first fall frost (Sep 6). 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 | Apr 12–26 | Jun 14–28 (transplant) | – |
| Pepper (sweet and hot) | Mar 29–Apr 12 | Jun 21–Jul 5 (transplant) | – |
| Eggplant | Mar 29–Apr 12 | Jun 21–Jul 5 (transplant) | – |
| Tomatillo | Apr 12–26 | Jun 14–28 (transplant) | – |
| Lettuce | Apr 12–26 | May 17–Jun 7 (transplant) May 10–Jun 21 (sow outdoors) | Jul 12–Aug 2 (transplant) Jun 28–Jul 26 (sowing) |
| Spinach | – | Apr 26–May 17 (sow outdoors) | Jul 12–Aug 2 (sowing) |
| Kale | Apr 12–26 | May 10–24 (transplant) May 10–24 (sow outdoors) | Jun 14–Jul 12 (transplant) May 31–Jun 28 (sowing) |
| Collards | Apr 12–26 | May 10–Jun 7 (transplant) May 10–Jun 7 (sow outdoors) | Jun 14–Jul 12 (transplant) |
| Broccoli | Mar 29–Apr 12 | May 10–24 (transplant) | May 31–Jun 28 (transplant) |
| Cabbage | Mar 29–Apr 12 | May 10–24 (transplant) | May 31–Jun 28 (transplant) |
| Cauliflower | Mar 29–Apr 12 | May 24–Jun 7 (transplant) | – |
| Brussels sprouts | Mar 15–29 | May 10–24 (transplant) | – |
| Kohlrabi | Apr 12–26 | May 10–24 (transplant) May 10–24 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Bok choy / Asian greens | – | May 10–24 (sow outdoors) | Jul 12–26 (sowing) |
| Arugula | – | May 10–Jun 7 (sow outdoors) | Jul 12–Aug 9 (sowing) |
| Mustard greens | – | May 10–31 (sow outdoors) | Jul 12–26 (sowing) |
| Swiss chard | Apr 26–May 10 | May 24–Jun 14 (transplant) May 24–Jun 21 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Beet | – | May 10–Jun 7 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Carrot | – | May 17–Jun 14 (sow outdoors) | – |
| Radish | – | May 3–Jun 14 (sow outdoors) | Jul 26–Aug 9 (sowing) |
| Turnip | – | May 10–31 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Parsnip | – | May 17–Jun 7 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 12–May 10 (sow outdoors) | Jun 14–28 (sowing) |
| Onion (bulbing) | Mar 15–29 | Apr 26–May 10 (transplant) | – |
| Green onion / scallion | – | Apr 26–May 24 (sow outdoors) | Jun 28–Jul 12 (sowing) |
| Leek | Mar 15–29 | May 10–24 (transplant) | – |
| Garlic | – | – | Jul 26–Aug 23 (sowing) |
| Shallot | – | Apr 26–May 10 (transplant) | Jul 26–Aug 23 (sowing) |
| Potato | – | May 10–24 (transplant) | – |
| Sweet potato | – | Jun 28–Jul 12 (transplant) | – |
| Sweet corn | – | Jun 14–28 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 14–28 (sow outdoors) | – |
| Bean, pole | – | Jun 14–28 (sow outdoors) | – |
| Lima bean | – | Jun 21–Jul 5 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 28–Jul 19 (sow outdoors) | – |
| Cucumber | May 10–17 | Jun 14–28 (transplant) Jun 14–28 (sow outdoors) | – |
| Summer squash / zucchini | May 10–17 | Jun 14–28 (transplant) Jun 14–28 (sow outdoors) | – |
| Winter squash | May 10–17 | Jun 14–28 (transplant) Jun 14–28 (sow outdoors) | – |
| Pumpkin | – | Jun 14–28 (sow outdoors) | – |
| Watermelon | May 10–17 | Jun 21–Jul 5 (transplant) Jun 21–Jul 5 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 10–17 | Jun 21–Jul 5 (transplant) Jun 21–Jul 5 (sow outdoors) | – |
| Okra | Apr 26–May 10 | Jun 21–Jul 5 (transplant) Jun 21–Jul 5 (sow outdoors) | – |
| Celery | Mar 15–29 | Jun 14–21 (transplant) | – |
| Basil | Apr 26–May 10 | Jun 14–28 (transplant) Jun 14–28 (sow outdoors) | – |
| Cilantro | – | May 24–Jun 21 (sow outdoors) | Jul 12–26 (sowing) |
| Parsley | Mar 29–Apr 12 | May 24–Jun 7 (transplant) May 17–Jun 7 (sow outdoors) | – |
| Dill | – | Jun 7–21 (sow outdoors) | Jul 12–26 (sowing) |
| Sunflower | – | Jun 7–21 (sow outdoors) | – |
| Asparagus (crowns) | – | May 10–24 (transplant) | – |
| Rhubarb (crowns) | – | May 10–24 (transplant) | – |
| Strawberry (plants) | – | May 10–24 (transplant) | Jun 28–Jul 26 (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: Riverside 7 SSW, OR (NOAA GHCN-Daily ID USC00357208), elevation 3,380 ft, 20.7 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Owyhee Dam, OR | 31 mi | May 7 | Oct 5 |
| Rockville 5 N, OR | 36 mi | May 29 | Sep 14 |
| Westfall, OR | 37 mi | May 7 | Oct 3 |
The average last-frost dates of these stations span 31 days, a rough guide to local variation. See data sources & methods.
Frost questions for 97906
When is the last frost in 97906?
The average (50% chance) last spring freeze of 32°F for ZIP 97906 is June 7. For a more cautious planting date, use June 28, when only 1 year in 10 still sees a later freeze.
When is the first frost in 97906?
The average first fall freeze is September 6. In 1 year in 10 it comes by August 22.
What hardiness zone is 97906?
ZIP 97906 is in USDA zone 6b (-5 to 0°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 97906 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
97917 97732 Crane 97913 Nyssa 97911 Juntura 97901 Adrian 97918 Vale 97902 97920
Other ZIP codes in Malheur County
89421 97901 97902 97903 97908 97909 97910 97911 97913 97914 97917 97918 97920 All Malheur County frost dates · Oregon frost dates
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- Freeze alerts
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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.