When to plant in Joliet, IL
USDA Zone 5bJoliet, Illinois frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Zone 5b means Joliet sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
JOLIET BRANDON RD DAM · 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 Joliet’s own odds, recorded at JOLIET BRANDON RD DAM.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 18 | May 1 | Apr 16 | Oct 2 | Oct 15 | Oct 27 |
| 32°F | May 7 | Apr 19 | Apr 3 | Oct 12 | Oct 25 | Nov 6 |
| 28°F | Apr 21 | Apr 5 | Mar 22 | Oct 23 | Nov 4 | Nov 21 |
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 Joliet, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 17 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.
Joliet planting FAQ
When is the last spring frost in Joliet, IL?
On average, the last spring frost in Joliet is around April 19 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Joliet, IL?
Expect Joliet's first fall frost near October 25 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Joliet in?
Joliet 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 Joliet?
There are roughly 189 frost-free days in Joliet (a moderate growing season), running from the average last frost around April 19 to the first fall frost near October 25.
When should I plant tomatoes in Joliet?
In Joliet, start tomato seeds indoors around February 22–March 8, then transplant seedlings outdoors around April 26 once the danger of frost has passed.
Never miss a window in Joliet
An email when it’s time to start seeds, transplant, and sow — timed to Joliet’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Shorewood · 6 km
- Crest Hill · 7 km
- Lockport · 13 km
- Romeoville · 13 km
- Minooka · 13 km
- Plainfield · 13 km
- Channahon · 14 km
- New Lenox · 15 km
Frost dates recorded at JOLIET BRANDON RD DAM, 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 Joliet, IL — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00114530. Retrieved from https://blissgarden.com/illinois/joliet.