Frost dates · USDA zone 5b
Frost dates for Ames, IA
Ames, IA sees its last 32 °F night of spring around April 26 and its first of fall around October 8 — a 164-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Apr 11 | Oct 21 |
| Median — 1 year in 2 | Apr 26 | Oct 8 |
| 1 year in 10 | May 9 | Sep 23 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 164 days median, at least 144 in 9 years of 10, at least 184 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Apr 14 and first of Oct 19.
Ames planting calendar, 2027
Every row runs from the median last frost (Apr 26) and median first frost (Oct 8) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Feb 1 | Mar 29 | Jul 17 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Apr 26 | May 26 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Apr 12 | Apr 12 | May 27 | 45 from sow |
| Genovese BasilGenovese | Mar 29 | May 10 | Jul 9 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Mar 1 | May 3 | Jul 17 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Feb 15 | May 10 | Aug 13 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Mar 1 | May 3 | Jul 17 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Mar 1 | May 3 | Jul 22 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Mar 1 | May 3 | Jul 22 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Apr 12 | Apr 12 | Jun 21 | 70 from sow |
| TomatilloToma Verde | Mar 15 | May 3 | Jul 12 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Mar 15 | May 3 | Jul 17 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Mar 15 | May 3 | Jul 22 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can Ames grow?
Each sauce, scheduled for a Ames container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Ames frost questions
When is the last frost in Ames, IA?
The median last 32 °F freeze at AMES MUNI AP, IA is April 26: half of years see a later one. One year in ten, a freeze still comes after May 9; nine years in ten, it comes after April 11. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Ames, IA?
The median first 32 °F freeze of fall is October 8. One year in ten it arrives before September 23; nine years in ten, before October 21.
How long is the growing season in Ames, IA?
164 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 144 days; one year in ten, at least 184 days.
What growing zone is Ames, IA?
USDA hardiness zone 5b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 50012. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in Ames, IA?
Start Roma VF (determinate paste) seeds indoors around Mar 15 and transplant around May 3, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for May 9. First ripe fruit lands around Jul 17.
When should I plant peppers in Ames, IA?
Sow jalapeño indoors on a heat mat around Mar 1; transplant no earlier than May 3, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jul 17.
Nearby in Iowa
- Ankenylast frost Apr 23
- Urbandalelast frost Apr 18
- Des Moineslast frost Apr 18
- West Des Moineslast frost Apr 18
- Cedar Fallslast frost Apr 27
- Waterloolast frost Apr 27
All Iowa frost dates → · How frost-date math drives a sowing calendar →