Frost dates · USDA zone 5b
Frost dates for Wheaton, IL
Wheaton, IL sees its last 32 °F night of spring around April 28 and its first of fall around October 16 — a 169-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 14 | Oct 29 |
| Median — 1 year in 2 | Apr 28 | Oct 16 |
| 1 year in 10 | May 14 | Oct 1 |
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: 169 days median, at least 148 in 9 years of 10, at least 188 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 16 and first of Oct 26.
Wheaton planting calendar, 2027
Every row runs from the median last frost (Apr 28) and median first frost (Oct 16) 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 3 | Mar 31 | Jul 19 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Apr 28 | May 28 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Apr 14 | Apr 14 | May 29 | 45 from sow |
| Genovese BasilGenovese | Mar 31 | May 12 | Jul 11 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Mar 3 | May 5 | Jul 19 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Feb 17 | May 12 | Aug 15 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Mar 3 | May 5 | Jul 19 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Mar 3 | May 5 | Jul 24 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Mar 3 | May 5 | Jul 24 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Apr 14 | Apr 14 | Jun 23 | 70 from sow |
| TomatilloToma Verde | Mar 17 | May 5 | Jul 14 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Mar 17 | May 5 | Jul 19 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Mar 17 | May 5 | Jul 24 | 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 Wheaton grow?
Each sauce, scheduled for a Wheaton container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Wheaton frost questions
When is the last frost in Wheaton, IL?
The median last 32 °F freeze at LISLE-MORTON ARBORETUM, IL is April 28: half of years see a later one. One year in ten, a freeze still comes after May 14; nine years in ten, it comes after April 14. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Wheaton, IL?
The median first 32 °F freeze of fall is October 16. One year in ten it arrives before October 1; nine years in ten, before October 29.
How long is the growing season in Wheaton, IL?
169 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 148 days; one year in ten, at least 188 days.
What growing zone is Wheaton, IL?
USDA hardiness zone 5b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 60187. 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 Wheaton, IL?
Start Roma VF (determinate paste) seeds indoors around Mar 17 and transplant around May 5, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for May 14. First ripe fruit lands around Jul 19.
When should I plant peppers in Wheaton, IL?
Sow jalapeño indoors on a heat mat around Mar 3; transplant no earlier than May 5, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jul 19.
Nearby in Illinois
- Lombardlast frost Apr 28
- Downers Grovelast frost Apr 28
- Napervillelast frost Apr 28
- Elmhurstlast frost Apr 16
- Auroralast frost Apr 19
- Bolingbrooklast frost Apr 20
All Illinois frost dates → · How frost-date math drives a sowing calendar →