When to plant in Ames, IA
USDA Zone 5bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Ames, Iowa — all computed from Ames's nearest NOAA weather station.
Zone 5b means Ames 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 Ames is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
AMES MUNI AP · 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 Ames’s own odds, recorded at AMES MUNI AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 17 | May 5 | Apr 21 | Sep 15 | Sep 28 | Oct 11 |
| 32°F | May 9 | Apr 26 | Apr 11 | Sep 23 | Oct 8 | Oct 21 |
| 28°F | May 1 | Apr 14 | Apr 1 | Oct 4 | Oct 19 | 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 Ames, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 13 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.
Ames planting FAQ
When is the last spring frost in Ames, IA?
Ames's average last spring frost falls near April 26 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Ames, IA?
Expect Ames's first fall frost near October 8 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Ames in?
Ames 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 Ames?
There are roughly 165 frost-free days in Ames (a moderate growing season), running from the average last frost around April 26 to the first fall frost near October 8.
When should I plant tomatoes in Ames?
In Ames, start tomato seeds indoors around March 1–March 15, then transplant seedlings outdoors around May 3 once the danger of frost has passed.
Never miss a window in Ames
An email when it’s time to start seeds, transplant, and sow — timed to Ames’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at AMES MUNI AP, 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 Ames, IA — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00094989. Retrieved from https://blissgarden.com/iowa/ames.