When to plant in Grayslake, IL
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in Grayslake, Illinois — is derived from the closest NOAA station with complete climate normals.
In zone 5b, Grayslake gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
MUNDELEIN 4 WSW · 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 Grayslake’s own odds, recorded at MUNDELEIN 4 WSW.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 26 | May 10 | Apr 25 | Sep 24 | Oct 9 | Oct 22 |
| 32°F | May 15 | Apr 29 | Apr 14 | Oct 4 | Oct 20 | Nov 1 |
| 28°F | May 4 | Apr 16 | Apr 2 | Oct 16 | Oct 31 | Nov 12 |
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 Grayslake, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 12 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.
Grayslake planting FAQ
When is the last spring frost in Grayslake, IL?
On average, the last spring frost in Grayslake is around April 29 (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 Grayslake, IL?
In Grayslake, the first 32°F freeze of fall lands around October 20 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Grayslake in?
Grayslake 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 Grayslake?
Grayslake has about 174 frost-free days — a moderate growing season — between the average last spring frost (April 29) and first fall frost (October 20).
When should I plant tomatoes in Grayslake?
For Grayslake, sow tomatoes indoors about March 4–March 18 and move the seedlings out around May 6, after the last spring frost.
Never miss a window in Grayslake
An email when it’s time to start seeds, transplant, and sow — timed to Grayslake’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Gages Lake · 4 km
- Round Lake · 6 km
- Round Lake Beach · 6 km
- Mundelein · 8 km
- Libertyville · 8 km
- Lindenhurst · 9 km
- Gurnee · 9 km
- Wauconda · 11 km
Frost dates recorded at MUNDELEIN 4 WSW, 10 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 Grayslake, IL — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00115961. Retrieved from https://blissgarden.com/illinois/grayslake.