When to plant in Newton, IA
USDA Zone 5bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Newton, Iowa — all computed from Newton's nearest NOAA weather station.
Zone 5b means Newton sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
The average first fall frost in Newton is now 8 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
NEWTON · 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 Newton’s own odds, recorded at NEWTON.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 13 | May 2 | Apr 19 | Sep 21 | Oct 4 | Oct 18 |
| 32°F | May 4 | Apr 22 | Apr 8 | Oct 1 | Oct 17 | Oct 28 |
| 28°F | Apr 25 | Apr 12 | Mar 30 | Oct 14 | Oct 26 | Nov 6 |
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 Newton, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 26 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.
Newton planting FAQ
When is the last spring frost in Newton, IA?
On average, the last spring frost in Newton is around April 22 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Newton, IA?
In Newton, the first 32°F freeze of fall lands around October 17 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Newton in?
Newton is in USDA hardiness zone 5b. In zone 5b, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Newton?
There are roughly 178 frost-free days in Newton (a moderate growing season), running from the average last frost around April 22 to the first fall frost near October 17.
When should I plant tomatoes in Newton?
In Newton, start tomato seeds indoors around February 25–March 11, then transplant seedlings outdoors around April 29 once the danger of frost has passed.
Never miss a window in Newton
An email when it’s time to start seeds, transplant, and sow — timed to Newton’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Pella · 34 km
- Altoona · 37 km
- Marshalltown · 39 km
- Pleasant Hill · 40 km
- Ankeny · 47 km
- Des Moines · 49 km
- Oskaloosa · 56 km
- Johnston · 57 km
Frost dates recorded at NEWTON, 2 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 Newton, IA — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00135992. Retrieved from https://blissgarden.com/iowa/newton.