When to plant in Naperville, IL
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in Naperville, Illinois — is derived from the closest NOAA station with complete climate normals.
In zone 5b, Naperville gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
LISLE-MORTON ARBORETUM · 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 Naperville’s own odds, recorded at LISLE-MORTON ARBORETUM.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 25 | May 9 | Apr 25 | Sep 22 | Oct 6 | Oct 18 |
| 32°F | May 14 | Apr 28 | Apr 14 | Oct 1 | Oct 16 | Oct 29 |
| 28°F | May 4 | Apr 16 | Apr 2 | Oct 12 | Oct 26 | Nov 8 |
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 Naperville, 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.
Naperville planting FAQ
When is the last spring frost in Naperville, IL?
Naperville's average last spring frost falls near April 28 — 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 Naperville, IL?
In Naperville, the first 32°F freeze of fall lands around October 16 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Naperville in?
Naperville 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 Naperville?
Naperville has about 171 frost-free days — a moderate growing season — between the average last spring frost (April 28) and first fall frost (October 16).
When should I plant tomatoes in Naperville?
For Naperville, sow tomatoes indoors about March 3–March 17 and move the seedlings out around May 5, after the last spring frost.
Never miss a window in Naperville
An email when it’s time to start seeds, transplant, and sow — timed to Naperville’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Lisle · 8 km
- Warrenville · 8 km
- Bolingbrook · 8 km
- Woodridge · 10 km
- Aurora · 11 km
- Downers Grove · 13 km
- Wheaton · 13 km
- Winfield · 14 km
Frost dates recorded at LISLE-MORTON ARBORETUM, 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 Naperville, IL — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00115097. Retrieved from https://blissgarden.com/illinois/naperville.