Frost Dates for Plainfield, IL
In Plainfield, IL, the average last spring frost is around Apr 20 and the average first fall frost around Oct 22, for a growing season of about 184 days. For frost-tender plants, wait until May 6, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Romeoville Wfo, IL weather station, 8 miles away, elevation 660 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | May 6 | Oct 7 |
| 20% | May 1 | Oct 14 |
| 30% | Apr 27 | Oct 17 |
| 40% | Apr 23 | Oct 20 |
| 50% | Apr 20 | Oct 22 |
| 60% | Apr 17 | Oct 25 |
| 70% | Apr 14 | Oct 27 |
| 80% | Apr 11 | Oct 30 |
| 90% | Apr 7 | Nov 3 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | May 1 | Oct 12 |
| Frost / freeze (32°F) | Apr 20 | Oct 22 |
| Hard freeze (28°F) | Apr 8 | Nov 1 |
Planting calendar for Plainfield
Transplant Apr 27 – May 11
Transplant May 4 – May 18
Transplant May 4 – May 18
Transplant Apr 27 – May 11
Sow or transplant Apr 27 – May 11
Sow or transplant Apr 27 – May 11
Sow or transplant May 4 – May 18
Sow or transplant Mar 23 – Apr 6
Fall sowing Aug 27 – Sep 24
Fall sowing Aug 27 – Sep 17
Fall sowing Aug 13 – Aug 27
Sow or transplant Mar 23 – Apr 6
Fall sowing Aug 13 – Sep 10
Transplant Apr 6 – Apr 20
Fall sowing Jul 30 – Aug 13
Transplant Mar 30 – Apr 13
Fall sowing Jul 30 – Aug 13
Fall sowing Jul 30 – Aug 13
Fall sowing Sep 10 – Oct 1
Fall sowing Aug 13 – Aug 27
Plant Mar 23 – Apr 6
Based on the average last frost (Apr 20) and first frost (Oct 22). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.