Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 50645 (Ionia, 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, New Hampton, IA (7 miles away).
- Average last spring frostMay 250% chance of a 32°F freeze after this date
- Average first fall frostOct 550% chance of a 32°F freeze by this date
- Growing season (frost-free)155 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°F avg. coldest night
Get The Dial for 50645 (Ionia)
Frost and freeze alerts from the NWS forecast for 50645, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
- Freeze alerts
- Soil-temp heads-up
- 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.
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 50645 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 early May.
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 17 |
| 50% (the "average" last frost) | May 2 |
| 10% (cautious: only 1 year in 10 freezes later) | May 14 |
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 23 |
| 50% (the "average" first frost) | Oct 5 |
| 90% (late: most years have frozen by now) | Oct 18 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 10 | Sep 28 |
| 32°F (freeze) | May 2 | Oct 5 |
| 28°F (hard freeze) | Apr 20 | Oct 15 |
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 50645
Dates count from your average last spring frost (May 2) and first fall frost (Oct 5). 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 7–21 | May 9–23 (transplant) | – |
| Pepper (sweet and hot) | Feb 21–Mar 7 | May 16–30 (transplant) | – |
| Eggplant | Feb 21–Mar 7 | May 16–30 (transplant) | – |
| Tomatillo | Mar 7–21 | May 9–23 (transplant) | – |
| Lettuce | Mar 7–21 | Apr 11–May 2 (transplant) Apr 4–May 16 (sow outdoors) | Aug 10–31 (transplant) Jul 27–Aug 24 (sowing) |
| Spinach | – | Mar 21–Apr 11 (sow outdoors) | Aug 10–31 (sowing) |
| Kale | Mar 7–21 | Apr 4–18 (transplant) Apr 4–18 (sow outdoors) | Jul 13–Aug 10 (transplant) Jun 29–Jul 27 (sowing) |
| Collards | Mar 7–21 | Apr 4–May 2 (transplant) Apr 4–May 2 (sow outdoors) | Jul 13–Aug 10 (transplant) Jun 29–Jul 27 (sowing) |
| Broccoli | Feb 21–Mar 7 | Apr 4–18 (transplant) | Jun 29–Jul 27 (transplant) |
| Cabbage | Feb 21–Mar 7 | Apr 4–18 (transplant) | Jun 29–Jul 27 (transplant) |
| Cauliflower | Feb 21–Mar 7 | Apr 18–May 2 (transplant) | Jun 29–Jul 27 (transplant) |
| Brussels sprouts | Feb 7–21 | Apr 4–18 (transplant) | Jun 15–Jul 6 (transplant) |
| Kohlrabi | Mar 7–21 | Apr 4–18 (transplant) Apr 4–18 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Bok choy / Asian greens | – | Apr 4–18 (sow outdoors) | Aug 10–24 (sowing) |
| Arugula | – | Apr 4–May 2 (sow outdoors) | Aug 10–Sep 7 (sowing) |
| Mustard greens | – | Apr 4–25 (sow outdoors) | Aug 10–24 (sowing) |
| Swiss chard | Mar 21–Apr 4 | Apr 18–May 9 (transplant) Apr 18–May 16 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Beet | – | Apr 4–May 2 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Carrot | – | Apr 11–May 9 (sow outdoors) | Jul 13–27 (sowing) |
| Radish | – | Mar 28–May 9 (sow outdoors) | Aug 24–Sep 7 (sowing) |
| Turnip | – | Apr 4–25 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Parsnip | – | Apr 11–May 2 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 7–Apr 4 (sow outdoors) | Jul 13–27 (sowing) |
| Onion (bulbing) | Feb 7–21 | Mar 21–Apr 4 (transplant) | – |
| Green onion / scallion | – | Mar 21–Apr 18 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Leek | Feb 7–21 | Apr 4–18 (transplant) | – |
| Garlic | – | – | Aug 24–Sep 21 (sowing) |
| Shallot | – | Mar 21–Apr 4 (transplant) | Aug 24–Sep 21 (sowing) |
| Potato | – | Apr 4–18 (transplant) | Jun 15–29 (transplant) |
| Sweet potato | – | May 23–Jun 6 (transplant) | – |
| Sweet corn | – | May 9–23 (sow outdoors) | – |
| Bean, bush (snap) | – | May 9–23 (sow outdoors) | – |
| Bean, pole | – | May 9–23 (sow outdoors) | – |
| Lima bean | – | May 16–30 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 23–Jun 13 (sow outdoors) | – |
| Cucumber | Apr 4–11 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Summer squash / zucchini | Apr 4–11 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Winter squash | Apr 4–11 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Pumpkin | – | May 9–23 (sow outdoors) | – |
| Watermelon | Apr 4–11 | May 16–30 (transplant) May 16–30 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 4–11 | May 16–30 (transplant) May 16–30 (sow outdoors) | – |
| Okra | Mar 21–Apr 4 | May 16–30 (transplant) May 16–30 (sow outdoors) | – |
| Celery | Feb 7–21 | May 9–16 (transplant) | – |
| Basil | Mar 21–Apr 4 | May 9–23 (transplant) May 9–23 (sow outdoors) | – |
| Cilantro | – | Apr 18–May 16 (sow outdoors) | Aug 10–24 (sowing) |
| Parsley | Feb 21–Mar 7 | Apr 18–May 2 (transplant) Apr 11–May 2 (sow outdoors) | – |
| Dill | – | May 2–16 (sow outdoors) | Aug 10–24 (sowing) |
| Sunflower | – | May 2–16 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 4–18 (transplant) | – |
| Rhubarb (crowns) | – | Apr 4–18 (transplant) | – |
| Strawberry (plants) | – | Apr 4–18 (transplant) | Jul 27–Aug 24 (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: New Hampton, IA (NOAA GHCN-Daily ID USC00135952), elevation 1,148 ft, 6.9 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Charles City, IA | 12 mi | Apr 30 | Oct 6 |
| Tripoli, IA | 17 mi | Apr 29 | Oct 9 |
| Osage, IA | 26 mi | Apr 30 | Oct 9 |
The average last-frost dates of these stations span 4 days, a rough guide to local variation. See data sources & methods.
Frost questions for 50645
When is the last frost in 50645?
The average (50% chance) last spring freeze of 32°F for ZIP 50645 is May 2. For a more cautious planting date, use May 14, when only 1 year in 10 still sees a later freeze.
When is the first frost in 50645?
The average first fall freeze is October 5. In 1 year in 10 it comes by September 23.
What hardiness zone is 50645?
ZIP 50645 is in USDA zone 5a (-20 to -15°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 50645 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
50658 Nashua 50659 New Hampton 50631 Frederika 50616 Charles City 50603 Alta Vista 50666 Plainfield 50620 Colwell 50630 Fredericksburg
Other ZIP codes in Chickasaw County
50603 50630 50658 50659 52154 All Chickasaw County frost dates · Iowa frost dates
Never miss a frost: get The Dial
Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
- Soil-temp heads-up
- 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.