USDA Hardiness Zone 5b
Frost Dates for 61231 — Aledo, Illinois
Averages from Aledo, Il US, the nearest reporting station, 0.8 miles away.
Plant tender crops after April 22, and expect the first autumn freeze around October 19. That leaves about 181 frost-free days.
- Last spring frost
- April 22
- First fall frost
- October 19
- Growing season
- 181 days
- Hardiness zone
- 5b
50% probability
50% probability
frost-free
-15 to -10°F annual low
Planting calendar for 61231
| When | What to do |
|---|---|
| February 11 – February 25 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| February 25 – March 11 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| March 25 – April 8 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| April 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by July 27 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by October 5 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| October 19 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after April 22 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Aledo, Illinois are past their last freeze. Harvest before October 19, which leaves roughly 181 frost-free days.
ZIP 61231 sits in USDA hardiness zone 5b, meaning the average coldest night of the year falls between -15 to -10°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.