Waterloo, IL planting zone & frost dates
Waterloo is in USDA hardiness zone 7a. The last spring frost usually comes around April 9 and the first fall frost around October 26, for a growing season of about 197 days.
Planting calendar for Waterloo
Dates are counted from the average last spring frost (April 9) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 12 – Feb 26 Transplant outdoors: Apr 16 – Apr 23 |
| Peppers | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Apr 23 – Apr 30 |
| Eggplant | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Apr 23 – Apr 30 |
| Broccoli | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Mar 12 – Mar 26 |
| Cabbage | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Mar 12 – Mar 26 |
| Onions (sets) | Plant outdoors: Mar 12 – Mar 26 |
| Peas | Sow outdoors: Feb 26 – Mar 12 |
| Spinach | Sow outdoors: Feb 26 – Mar 12 |
| Lettuce | Sow outdoors: Mar 12 – Mar 26 |
| Carrots | Sow outdoors: Mar 12 – Mar 26 |
| Potatoes | Plant outdoors: Mar 12 – Mar 26 |
| Beans | Sow outdoors: Apr 16 – Apr 23 |
| Sweet corn | Sow outdoors: Apr 16 – Apr 23 |
| Cucumbers | Sow outdoors: Apr 16 – Apr 23 |
| Squash & zucchini | Sow outdoors: Apr 16 – Apr 23 |
| Basil | Start seeds indoors: Feb 26 – Mar 12 Transplant outdoors: Apr 16 – Apr 23 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 31 (8 weeks before the average first fall frost on Oct 26).
Useful for zone 7a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 25 | Apr 9 | Apr 25 |
| First 32°F frost in fall is before | Nov 8 | Oct 26 | Oct 14 |
How to read it: in spring there is a 10% chance of a frost after April 25, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 14. A hard freeze (28°F) usually ends around March 31.
Hardiness zone by ZIP code in Waterloo
- 62298 zone 7a
Nearby cities
- Columbia zone 7a, last frost Apr 6
- Cahokia zone 7a, last frost Apr 6
- Belleville zone 7a, last frost Apr 12
- Swansea zone 7a, last frost Apr 12
- East Saint Louis zone 7a, last frost Apr 8
- Fairview Heights zone 7a, last frost Apr 8
- Shiloh zone 6b, last frost Apr 12
- O'Fallon zone 7a, last frost Apr 12
Questions
What growing zone is Waterloo, IL?
Waterloo is in USDA Plant Hardiness Zone 7a (average extreme winter low 0°F to 5°F), according to the USDA 2023 map.
When is the last frost in Waterloo?
The average last spring frost (32°F) in Waterloo is April 9. There is still a 10% chance of frost until April 25.
When can I plant tomatoes in Waterloo?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 16 – Apr 23. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Festus, MO (USC00232850), 24.5 km (15.2 mi) from the city center, elevation 183 m, based on 25 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.