When to plant in Roscoe, IL
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in Roscoe, Illinois — is derived from the closest NOAA station with complete climate normals.
Zone 5b means Roscoe sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
The average last spring frost in Roscoe is now 8 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
BELOIT · 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 Roscoe’s own odds, recorded at BELOIT.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 27 | May 11 | Apr 29 | Sep 21 | Oct 1 | Oct 14 |
| 32°F | May 16 | May 1 | Apr 17 | Sep 28 | Oct 12 | Oct 24 |
| 28°F | May 4 | Apr 20 | Apr 4 | Oct 9 | Oct 23 | Nov 4 |
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 Roscoe, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 24 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.
Roscoe planting FAQ
When is the last spring frost in Roscoe, IL?
Plan for the last spring frost in Roscoe around May 1 (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 Roscoe, IL?
Expect Roscoe's first fall frost near October 12 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Roscoe in?
Roscoe 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 Roscoe?
There are roughly 164 frost-free days in Roscoe (a moderate growing season), running from the average last frost around May 1 to the first fall frost near October 12.
When should I plant tomatoes in Roscoe?
In Roscoe, start tomato seeds indoors around March 6–March 20, then transplant seedlings outdoors around May 8 once the danger of frost has passed.
Never miss a window in Roscoe
An email when it’s time to start seeds, transplant, and sow — timed to Roscoe’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Machesney Park · 7 km
- Loves Park · 10 km
- Beloit · 11 km
- Rockford · 19 km
- Belvidere · 20 km
- Janesville · 29 km
- Elkhorn · 47 km
- Woodstock · 49 km
Frost dates recorded at BELOIT, 9 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 Roscoe, IL — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00470696. Retrieved from https://blissgarden.com/illinois/roscoe.