When to plant in Romeoville, IL
USDA Zone 6aRomeoville, Illinois frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Zone 6a means Romeoville sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
ROMEOVILLE WFO · 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 Romeoville’s own odds, recorded at ROMEOVILLE WFO.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 17 | May 1 | Apr 17 | Sep 28 | Oct 12 | Oct 24 |
| 32°F | May 6 | Apr 20 | Apr 7 | Oct 7 | Oct 22 | Nov 3 |
| 28°F | Apr 23 | Apr 8 | Mar 27 | Oct 19 | Nov 1 | Nov 15 |
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 Romeoville, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 21 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.
Romeoville planting FAQ
When is the last spring frost in Romeoville, IL?
Plan for the last spring frost in Romeoville around April 20 (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 Romeoville, IL?
In Romeoville, the first 32°F freeze of fall lands around October 22 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Romeoville in?
Romeoville is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Romeoville?
There are roughly 185 frost-free days in Romeoville (a moderate growing season), running from the average last frost around April 20 to the first fall frost near October 22.
When should I plant tomatoes in Romeoville?
In Romeoville, start tomato seeds indoors around February 23–March 9, then transplant seedlings outdoors around April 27 once the danger of frost has passed.
Never miss a window in Romeoville
An email when it’s time to start seeds, transplant, and sow — timed to Romeoville’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Crest Hill · 6 km
- Bolingbrook · 7 km
- Lockport · 7 km
- Plainfield · 10 km
- Lemont · 11 km
- Homer Glen · 13 km
- Joliet · 13 km
- Woodridge · 13 km
Frost dates recorded at ROMEOVILLE WFO, 3 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 Romeoville, IL — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00117457. Retrieved from https://blissgarden.com/illinois/romeoville.