When to plant in Crystal Lake, IL
USDA Zone 5bCrystal Lake, 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 Crystal Lake sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
CRYSTAL LAKE 4NW · 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 Crystal Lake’s own odds, recorded at CRYSTAL LAKE 4NW.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 21 | May 5 | Apr 23 | Sep 25 | Oct 11 | Oct 24 |
| 32°F | May 9 | Apr 25 | Apr 11 | Oct 7 | Oct 22 | Nov 4 |
| 28°F | Apr 27 | Apr 12 | Mar 31 | Oct 20 | 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 Crystal Lake, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 19 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.
Crystal Lake planting FAQ
When is the last spring frost in Crystal Lake, IL?
Crystal Lake's average last spring frost falls near April 25 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Crystal Lake, IL?
Expect Crystal Lake's first fall frost near October 22 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Crystal Lake in?
Crystal Lake 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 Crystal Lake?
There are roughly 180 frost-free days in Crystal Lake (a moderate growing season), running from the average last frost around April 25 to the first fall frost near October 22.
When should I plant tomatoes in Crystal Lake?
In Crystal Lake, start tomato seeds indoors around February 28–March 14, then transplant seedlings outdoors around May 2 once the danger of frost has passed.
Never miss a window in Crystal Lake
An email when it’s time to start seeds, transplant, and sow — timed to Crystal Lake’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Lake in the Hills · 6 km
- Cary · 7 km
- Algonquin · 8 km
- Huntley · 12 km
- Woodstock · 12 km
- McHenry · 12 km
- Carpentersville · 13 km
- Wauconda · 17 km
Frost dates recorded at CRYSTAL LAKE 4NW, 6 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 Crystal Lake, IL — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00112048. Retrieved from https://blissgarden.com/illinois/crystal-lake.