Frost dates for ZIP 50621 (Conrad, 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, Marshalltown Muni AP, IA (9 miles away).
- Average last spring frostApr 3050% chance of a 32°F freeze after this date
- Average first fall frostOct 650% chance of a 32°F freeze by this date
- Growing season (frost-free)159 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°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
55°F 55°F or warmer
24-hour average · latest 55°F, as of Oct 17, 10:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Ames (45 mi), Des Moines 17 E (51 mi).
4-inch depth
57°F 55°F or warmer
24-hour average · latest 56°F, as of Oct 17, 10:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Ames (45 mi), Des Moines 17 E (51 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 50621 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: 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 15 |
| 50% (the "average" last frost) | Apr 30 |
| 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 22 |
| 50% (the "average" first frost) | Oct 6 |
| 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 7 | Sep 26 |
| 32°F (freeze) | Apr 30 | Oct 6 |
| 28°F (hard freeze) | Apr 19 | Oct 16 |
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 50621
Dates count from your average last spring frost (Apr 30) and first fall frost (Oct 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 | Mar 5–19 | May 7–21 (transplant) | – |
| Pepper (sweet and hot) | Feb 19–Mar 5 | May 14–28 (transplant) | – |
| Eggplant | Feb 19–Mar 5 | May 14–28 (transplant) | – |
| Tomatillo | Mar 5–19 | May 7–21 (transplant) | – |
| Lettuce | Mar 5–19 | Apr 9–30 (transplant) Apr 2–May 14 (sow outdoors) | Aug 11–Sep 1 (transplant) Jul 28–Aug 25 (sowing) |
| Spinach | – | Mar 19–Apr 9 (sow outdoors) | Aug 11–Sep 1 (sowing) |
| Kale | Mar 5–19 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | Jul 14–Aug 11 (transplant) Jun 30–Jul 28 (sowing) |
| Collards | Mar 5–19 | Apr 2–30 (transplant) Apr 2–30 (sow outdoors) | Jul 14–Aug 11 (transplant) Jun 30–Jul 28 (sowing) |
| Broccoli | Feb 19–Mar 5 | Apr 2–16 (transplant) | Jun 30–Jul 28 (transplant) |
| Cabbage | Feb 19–Mar 5 | Apr 2–16 (transplant) | Jun 30–Jul 28 (transplant) |
| Cauliflower | Feb 19–Mar 5 | Apr 16–30 (transplant) | Jun 30–Jul 28 (transplant) |
| Brussels sprouts | Feb 5–19 | Apr 2–16 (transplant) | Jun 16–Jul 7 (transplant) |
| Kohlrabi | Mar 5–19 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | Jul 28–Aug 11 (sowing) |
| Bok choy / Asian greens | – | Apr 2–16 (sow outdoors) | Aug 11–25 (sowing) |
| Arugula | – | Apr 2–30 (sow outdoors) | Aug 11–Sep 8 (sowing) |
| Mustard greens | – | Apr 2–23 (sow outdoors) | Aug 11–25 (sowing) |
| Swiss chard | Mar 19–Apr 2 | Apr 16–May 7 (transplant) Apr 16–May 14 (sow outdoors) | Jul 28–Aug 11 (sowing) |
| Beet | – | Apr 2–30 (sow outdoors) | Jul 28–Aug 11 (sowing) |
| Carrot | – | Apr 9–May 7 (sow outdoors) | Jul 14–28 (sowing) |
| Radish | – | Mar 26–May 7 (sow outdoors) | Aug 25–Sep 8 (sowing) |
| Turnip | – | Apr 2–23 (sow outdoors) | Jul 28–Aug 11 (sowing) |
| Parsnip | – | Apr 9–30 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 5–Apr 2 (sow outdoors) | Jul 14–28 (sowing) |
| Onion (bulbing) | Feb 5–19 | Mar 19–Apr 2 (transplant) | – |
| Green onion / scallion | – | Mar 19–Apr 16 (sow outdoors) | Jul 28–Aug 11 (sowing) |
| Leek | Feb 5–19 | Apr 2–16 (transplant) | – |
| Garlic | – | – | Aug 25–Sep 22 (sowing) |
| Shallot | – | Mar 19–Apr 2 (transplant) | Aug 25–Sep 22 (sowing) |
| Potato | – | Apr 2–16 (transplant) | Jun 16–30 (transplant) |
| Sweet potato | – | May 21–Jun 4 (transplant) | – |
| Sweet corn | – | May 7–21 (sow outdoors) | – |
| Bean, bush (snap) | – | May 7–21 (sow outdoors) | – |
| Bean, pole | – | May 7–21 (sow outdoors) | – |
| Lima bean | – | May 14–28 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 21–Jun 11 (sow outdoors) | – |
| Cucumber | Apr 2–9 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Summer squash / zucchini | Apr 2–9 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Winter squash | Apr 2–9 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Pumpkin | – | May 7–21 (sow outdoors) | – |
| Watermelon | Apr 2–9 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 2–9 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Okra | Mar 19–Apr 2 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Celery | Feb 5–19 | May 7–14 (transplant) | – |
| Basil | Mar 19–Apr 2 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Cilantro | – | Apr 16–May 14 (sow outdoors) | Aug 11–25 (sowing) |
| Parsley | Feb 19–Mar 5 | Apr 16–30 (transplant) Apr 9–30 (sow outdoors) | – |
| Dill | – | Apr 30–May 14 (sow outdoors) | Aug 11–25 (sowing) |
| Sunflower | – | Apr 30–May 14 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 2–16 (transplant) | – |
| Rhubarb (crowns) | – | Apr 2–16 (transplant) | – |
| Strawberry (plants) | – | Apr 2–16 (transplant) | Jul 28–Aug 25 (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: Marshalltown Muni AP, IA (NOAA GHCN-Daily ID USW00094988), elevation 974 ft, 9.3 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Grundy Ctr, IA | 11 mi | Apr 29 | Oct 9 |
| Eldora, IA | 12 mi | Apr 27 | Oct 10 |
| Marshalltown, IA | 13 mi | Apr 28 | Oct 7 |
The average last-frost dates of these stations span 3 days, a rough guide to local variation. See data sources & methods.
Frost questions for 50621
When is the last frost in 50621?
The average (50% chance) last spring freeze of 32°F for ZIP 50621 is April 30. 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 50621?
The average first fall freeze is October 6. In 1 year in 10 it comes by September 22.
What hardiness zone is 50621?
ZIP 50621 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 50621 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
50269 Whitten 50609 Beaman 50148 Liscomb 50258 Union 50638 Grundy Center 50005 Albion 50627 Eldora 50652 Lincoln
Other ZIP codes in Grundy County
50609 50624 50638 50642 50657 50669 50673 50680 All Grundy County frost dates · Iowa frost dates
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