When to plant in Waterloo, IL
USDA Zone 7aWaterloo, Illinois frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
These dates come from a station roughly 25 km away, the closest with full normals; terrain around Waterloo (elevation, water, pavement) can move your real frost dates a few days either way. In zone 7a, Waterloo supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
The average last spring frost in Waterloo is now 7 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
FESTUS · 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 Waterloo’s own odds, recorded at FESTUS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 8 | Apr 22 | Apr 5 | Oct 4 | Oct 17 | Oct 28 |
| 32°F | Apr 25 | Apr 9 | Mar 25 | Oct 14 | Oct 26 | Nov 8 |
| 28°F | Apr 15 | Mar 31 | Mar 12 | Oct 23 | Nov 5 | Nov 23 |
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 Waterloo, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 26 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.
Waterloo planting FAQ
When is the last spring frost in Waterloo, IL?
Waterloo's average last spring frost falls near April 9 — 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 Waterloo, IL?
In Waterloo, 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 Waterloo in?
Waterloo is in USDA hardiness zone 7a. In zone 7a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Waterloo?
Waterloo has about 200 frost-free days — a moderate growing season — between the average last spring frost (April 9) and first fall frost (October 26).
When should I plant tomatoes in Waterloo?
For Waterloo, sow tomatoes indoors about February 12–February 26 and move the seedlings out around April 16, after the last spring frost.
Never miss a window in Waterloo
An email when it’s time to start seeds, transplant, and sow — timed to Waterloo’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Columbia · 14 km
- Oakville · 19 km
- Arnold · 21 km
- Mehlville · 23 km
- Belleville · 24 km
- Lemay · 24 km
- Concord · 26 km
- Cahokia Heights · 26 km
Frost dates recorded at FESTUS, 25 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 Waterloo, IL — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00232850. Retrieved from https://blissgarden.com/illinois/waterloo.