When to plant in Prospect Heights, IL
USDA Zone 6aProspect Heights, 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 Prospect Heights 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 Prospect Heights is now 6 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
CHICAGO PALWAUKEE AP · 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 Prospect Heights’s own odds, recorded at CHICAGO PALWAUKEE AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 15 | Apr 30 | Apr 16 | Oct 1 | Oct 16 | Oct 27 |
| 32°F | May 3 | Apr 19 | Apr 4 | Oct 13 | Oct 26 | Nov 9 |
| 28°F | Apr 20 | Apr 5 | Mar 22 | Oct 26 | Nov 7 | 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 Prospect Heights, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 13 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.
Prospect Heights planting FAQ
When is the last spring frost in Prospect Heights, IL?
Prospect Heights's average last spring frost falls near April 19 — 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 Prospect Heights, IL?
In Prospect Heights, the first 32°F freeze of fall lands around October 26 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Prospect Heights in?
Prospect Heights 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 Prospect Heights?
There are roughly 190 frost-free days in Prospect Heights (a moderate growing season), running from the average last frost around April 19 to the first fall frost near October 26.
When should I plant tomatoes in Prospect Heights?
In Prospect Heights, 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 Prospect Heights
An email when it’s time to start seeds, transplant, and sow — timed to Prospect Heights’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Wheeling · 3 km
- Arlington Heights · 4 km
- Mount Prospect · 4 km
- Buffalo Grove · 7 km
- Des Plaines · 8 km
- Northbrook · 8 km
- Rolling Meadows · 9 km
- Glenview · 9 km
Frost dates recorded at CHICAGO PALWAUKEE AP, 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 Prospect Heights, IL — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00004838. Retrieved from https://blissgarden.com/illinois/prospect-heights.