When to plant in DeKalb, IL
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in DeKalb, Illinois — is derived from the closest NOAA station with complete climate normals.
In zone 5b, DeKalb gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average first fall frost in DeKalb is now 7 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
DE KALB · 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 DeKalb’s own odds, recorded at DE KALB.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 22 | May 4 | Apr 20 | Sep 25 | Oct 7 | Oct 21 |
| 32°F | May 10 | Apr 24 | Apr 9 | Oct 4 | Oct 18 | Oct 31 |
| 28°F | Apr 29 | Apr 13 | Mar 30 | Oct 14 | Oct 28 | 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 DeKalb, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 27 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.
DeKalb planting FAQ
When is the last spring frost in DeKalb, IL?
On average, the last spring frost in DeKalb is around April 24 (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 DeKalb, IL?
Expect DeKalb's first fall frost near October 18 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is DeKalb in?
DeKalb 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 DeKalb?
DeKalb has about 177 frost-free days — a moderate growing season — between the average last spring frost (April 24) and first fall frost (October 18).
When should I plant tomatoes in DeKalb?
For DeKalb, sow tomatoes indoors about February 27–March 13 and move the seedlings out around May 1, after the last spring frost.
Never miss a window in DeKalb
An email when it’s time to start seeds, transplant, and sow — timed to DeKalb’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Sycamore · 10 km
- Campton Hills · 27 km
- Pingree Grove · 31 km
- Plano · 33 km
- Geneva · 35 km
- North Aurora · 36 km
- St. Charles · 36 km
- South Elgin · 36 km
Frost dates recorded at DE KALB, 2 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 DeKalb, IL — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00112223. Retrieved from https://blissgarden.com/illinois/dekalb.