When to plant in Marshalltown, IA
USDA Zone 5aEverything below — frost dates, hardiness zone, and what to plant when in Marshalltown, Iowa — is derived from the closest NOAA station with complete climate normals.
In zone 5a, Marshalltown gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average first fall frost in Marshalltown is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
MARSHALLTOWN · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Marshalltown’s own odds, recorded at MARSHALLTOWN.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 20 | May 7 | Apr 25 | Sep 16 | Sep 28 | Oct 11 |
| 32°F | May 11 | Apr 28 | Apr 13 | Sep 22 | Oct 7 | Oct 21 |
| 28°F | May 2 | Apr 17 | Apr 3 | Oct 1 | Oct 18 | Oct 31 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Marshalltown, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 27 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Marshalltown planting FAQ
When is the last spring frost in Marshalltown, IA?
Plan for the last spring frost in Marshalltown around April 28 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Marshalltown, IA?
In Marshalltown, the first 32°F freeze of fall lands around October 7 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Marshalltown in?
Marshalltown is in USDA hardiness zone 5a. In zone 5a, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Marshalltown?
Marshalltown has about 162 frost-free days — a moderate growing season — between the average last spring frost (April 28) and first fall frost (October 7).
When should I plant tomatoes in Marshalltown?
For Marshalltown, sow tomatoes indoors about March 3–March 17 and move the seedlings out around May 5, after the last spring frost.
Never miss a window in Marshalltown
An email when it’s time to start seeds, transplant, and sow — timed to Marshalltown’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Newton · 39 km
- Ames · 59 km
- Altoona · 64 km
- Cedar Falls · 65 km
- Ankeny · 67 km
- Waterloo · 68 km
- Pleasant Hill · 69 km
- Pella · 70 km
Frost dates recorded at MARSHALLTOWN, 4 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Marshalltown, IA — Frost Dates & Zone 5a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00135198. Retrieved from https://blissgarden.com/iowa/marshalltown.