Frost dates for ZIP 52308 (Millersburg, IA)
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, Williamsburg 1E, IA (11 miles away).
- Average last spring frostApr 2850% chance of a 32°F freeze after this date
- Average first fall frostOct 950% chance of a 32°F freeze by this date
- Growing season (frost-free)164 daysmedian, 32°F threshold
- USDA hardiness zone5b-15 to -10°F avg. coldest night
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This week in your yard
As of Oct 17, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
57°F 55°F or warmer
24-hour average · latest 57°F, as of Oct 17, 9:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Des Moines 17 E (58 mi).
4-inch depth
59°F 55°F or warmer
24-hour average · latest 58°F, as of Oct 17, 9:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Des Moines 17 E (58 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 52308 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 59°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: North (cool-season). 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 14 |
| 50% (the "average" last frost) | Apr 28 |
| 10% (cautious: only 1 year in 10 freezes later) | May 12 |
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 24 |
| 50% (the "average" first frost) | Oct 9 |
| 90% (late: most years have frozen by now) | Oct 21 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 7 | Sep 30 |
| 32°F (freeze) | Apr 28 | Oct 9 |
| 28°F (hard freeze) | Apr 18 | Oct 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 52308
Dates count from your average last spring frost (Apr 28) and first fall frost (Oct 9). 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 3–17 | May 5–19 (transplant) | – |
| Pepper (sweet and hot) | Feb 17–Mar 3 | May 12–26 (transplant) | – |
| Eggplant | Feb 17–Mar 3 | May 12–26 (transplant) | – |
| Tomatillo | Mar 3–17 | May 5–19 (transplant) | – |
| Lettuce | Mar 3–17 | Apr 7–28 (transplant) Mar 31–May 12 (sow outdoors) | Aug 14–Sep 4 (transplant) Jul 31–Aug 28 (sowing) |
| Spinach | – | Mar 17–Apr 7 (sow outdoors) | Aug 14–Sep 4 (sowing) |
| Kale | Mar 3–17 | Mar 31–Apr 14 (transplant) Mar 31–Apr 14 (sow outdoors) | Jul 17–Aug 14 (transplant) Jul 3–31 (sowing) |
| Collards | Mar 3–17 | Mar 31–Apr 28 (transplant) Mar 31–Apr 28 (sow outdoors) | Jul 17–Aug 14 (transplant) Jul 3–31 (sowing) |
| Broccoli | Feb 17–Mar 3 | Mar 31–Apr 14 (transplant) | Jul 3–31 (transplant) |
| Cabbage | Feb 17–Mar 3 | Mar 31–Apr 14 (transplant) | Jul 3–31 (transplant) |
| Cauliflower | Feb 17–Mar 3 | Apr 14–28 (transplant) | Jul 3–31 (transplant) |
| Brussels sprouts | Feb 3–17 | Mar 31–Apr 14 (transplant) | Jun 19–Jul 10 (transplant) |
| Kohlrabi | Mar 3–17 | Mar 31–Apr 14 (transplant) Mar 31–Apr 14 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Bok choy / Asian greens | – | Mar 31–Apr 14 (sow outdoors) | Aug 14–28 (sowing) |
| Arugula | – | Mar 31–Apr 28 (sow outdoors) | Aug 14–Sep 11 (sowing) |
| Mustard greens | – | Mar 31–Apr 21 (sow outdoors) | Aug 14–28 (sowing) |
| Swiss chard | Mar 17–31 | Apr 14–May 5 (transplant) Apr 14–May 12 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Beet | – | Mar 31–Apr 28 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Carrot | – | Apr 7–May 5 (sow outdoors) | Jul 17–31 (sowing) |
| Radish | – | Mar 24–May 5 (sow outdoors) | Aug 28–Sep 11 (sowing) |
| Turnip | – | Mar 31–Apr 21 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Parsnip | – | Apr 7–28 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 3–31 (sow outdoors) | Jul 17–31 (sowing) |
| Onion (bulbing) | Feb 3–17 | Mar 17–31 (transplant) | – |
| Green onion / scallion | – | Mar 17–Apr 14 (sow outdoors) | Jul 31–Aug 14 (sowing) |
| Leek | Feb 3–17 | Mar 31–Apr 14 (transplant) | – |
| Garlic | – | – | Aug 28–Sep 25 (sowing) |
| Shallot | – | Mar 17–31 (transplant) | Aug 28–Sep 25 (sowing) |
| Potato | – | Mar 31–Apr 14 (transplant) | Jun 19–Jul 3 (transplant) |
| Sweet potato | – | May 19–Jun 2 (transplant) | – |
| Sweet corn | – | May 5–19 (sow outdoors) | – |
| Bean, bush (snap) | – | May 5–19 (sow outdoors) | – |
| Bean, pole | – | May 5–19 (sow outdoors) | – |
| Lima bean | – | May 12–26 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 19–Jun 9 (sow outdoors) | – |
| Cucumber | Mar 31–Apr 7 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Summer squash / zucchini | Mar 31–Apr 7 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Winter squash | Mar 31–Apr 7 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Pumpkin | – | May 5–19 (sow outdoors) | – |
| Watermelon | Mar 31–Apr 7 | May 12–26 (transplant) May 12–26 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 31–Apr 7 | May 12–26 (transplant) May 12–26 (sow outdoors) | – |
| Okra | Mar 17–31 | May 12–26 (transplant) May 12–26 (sow outdoors) | – |
| Celery | Feb 3–17 | May 5–12 (transplant) | – |
| Basil | Mar 17–31 | May 5–19 (transplant) May 5–19 (sow outdoors) | – |
| Cilantro | – | Apr 14–May 12 (sow outdoors) | Aug 14–28 (sowing) |
| Parsley | Feb 17–Mar 3 | Apr 14–28 (transplant) Apr 7–28 (sow outdoors) | – |
| Dill | – | Apr 28–May 12 (sow outdoors) | Aug 14–28 (sowing) |
| Sunflower | – | Apr 28–May 12 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 31–Apr 14 (transplant) | – |
| Rhubarb (crowns) | – | Mar 31–Apr 14 (transplant) | – |
| Strawberry (plants) | – | Mar 31–Apr 14 (transplant) | Jul 31–Aug 28 (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: Williamsburg 1E, IA (NOAA GHCN-Daily ID USC00139067), elevation 780 ft, 10.5 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Sigourney, IA | 17 mi | Apr 24 | Oct 15 |
| Belle Plaine, IA | 22 mi | Apr 28 | Oct 10 |
| Oskaloosa, IA | 31 mi | Apr 21 | Oct 16 |
The average last-frost dates of these stations span 7 days, a rough guide to local variation. See data sources & methods.
Frost questions for 52308
When is the last frost in 52308?
The average (50% chance) last spring freeze of 32°F for ZIP 52308 is April 28. For a more cautious planting date, use May 12, when only 1 year in 10 still sees a later freeze.
When is the first frost in 52308?
The average first fall freeze is October 9. In 1 year in 10 it comes by September 24.
What hardiness zone is 52308?
ZIP 52308 is in USDA zone 5b (-15 to -10°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 52308 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
52316 North English 52355 Webster 52361 Williamsburg 52335 South English 52222 Deep River 50136 Keswick 52251 Ladora 52221 Guernsey
Other ZIP codes in Iowa County
52203 52220 52236 52251 52301 52307 52316 52325 52334 52347 52361 All Iowa County frost dates · Iowa frost dates
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