When to plant in Cahokia, IL
Planting dates worked out from Cahokia's own frost records, not a generic zone chart.
Safe to plant out
Apr 20
1 year in 10 has a later frost
Average last frost
Apr 9
about a 50% chance of a later one
Average first fall frost
Oct 24
1 year in 10 by Oct 14
Frost-free days
198
median, 1991–2020
Station used: Cahokia · 0.6 km away · station 122 m, town 124 m. How we match towns to stations
This season
Plan your garden.
Planting dates for common crops
| Crop | Start indoors | Plant out or sow | Harvest from |
|---|---|---|---|
| Tomato | Feb 23 – Mar 9 | Apr 20 – May 4 | Jun 14 |
| Sweet pepper | Feb 9 – Feb 23 | Apr 20 – May 4 | Jun 19 |
| Lettuce (leaf) | Feb 5 – Feb 12 | Mar 12 – Mar 26 | Apr 21 |
| Peas | — | Mar 6 – Apr 3 | Apr 30 |
| Bush beans | — | Apr 13 – May 4 | Jun 2 |
| Carrot | — | Mar 19 – Apr 30 | May 18 |
| Beet | — | Mar 17 – Apr 28 | May 6 |
| Potato | — | Mar 19 – Apr 9 | May 28 |
| Kale | Jan 30 – Feb 13 | Mar 13 – Mar 27 | Apr 25 |
| Broccoli | Jan 29 – Feb 12 | Mar 12 – Apr 2 | May 11 |
| Cucumber | Mar 23 – Mar 30 | Apr 20 – May 4 | Jun 9 |
| Summer squash and zucchini | Mar 23 – Mar 30 | Apr 20 – May 4 | Jun 4 |
| Winter squash | Mar 23 – Mar 30 | Apr 20 – May 4 | Jul 9 |
| Sweet corn | — | Apr 13 – May 4 | Jun 12 |
| Onion (from sets) | — | Mar 12 – Apr 2 | Jun 10 |
| Garlic | — | Oct 10 – Nov 7 (fall) | following summer |
| Spinach | — | Mar 6 – Apr 3 | Apr 13 |
| Basil | Mar 9 – Mar 23 | Apr 20 – May 4 | Jun 16 |
Cahokia's weather over time
How the growing season has shifted here, year by year, from the station's own records.
Each year's last spring frostLong-term trend
See the data as a table
| Year | Last spring frost |
|---|---|
| 1970 | Apr 9 |
| 1972 | Apr 9 |
| 1974 | Apr 9 |
| 1975 | Apr 12 |
| 1976 | Apr 26 |
| 1977 | Mar 25 |
| 1979 | Apr 7 |
| 1984 | Mar 31 |
| 1985 | Apr 8 |
| 1986 | Apr 22 |
| 1987 | Apr 11 |
| 1988 | Apr 28 |
| 1989 | May 6 |
| 1990 | Apr 17 |
| 1991 | Mar 30 |
| 1992 | Apr 28 |
| 1993 | Apr 17 |
| 1994 | Apr 7 |
| 1995 | Apr 5 |
| 1996 | Apr 10 |
| 1997 | Apr 14 |
| 1998 | Apr 5 |
| 1999 | Mar 27 |
| 2000 | Apr 9 |
| 2001 | Apr 18 |
| 2002 | Apr 5 |
| 2004 | Apr 5 |
| 2005 | Mar 20 |
| 2006 | Apr 9 |
| 2007 | Apr 13 |
| 2008 | Apr 29 |
| 2009 | Apr 9 |
| 2010 | Mar 27 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1972 | 192 |
| 1974 | 176 |
| 1975 | 196 |
| 1976 | 174 |
| 1977 | 201 |
| 1979 | 185 |
| 1985 | 174 |
| 1986 | 200 |
| 1987 | 174 |
| 1988 | 159 |
| 1989 | 139 |
| 1990 | 175 |
| 1991 | 198 |
| 1992 | 173 |
| 1993 | 196 |
| 1994 | 201 |
| 1995 | 202 |
| 1997 | 190 |
| 1998 | 213 |
| 1999 | 204 |
| 2000 | 180 |
| 2001 | 181 |
| 2004 | 217 |
| 2005 | 219 |
| 2006 | 186 |
| 2007 | 198 |
| 2008 | 181 |
| 2009 | 191 |
| 2010 | 215 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1972 | 20.2 °C |
| 1974 | 20.0 °C |
| 1975 | 20.7 °C |
| 1976 | 19.8 °C |
| 1977 | 21.6 °C |
| 1979 | 19.9 °C |
| 1981 | 21.2 °C |
| 1985 | 21.1 °C |
| 1987 | 22.4 °C |
| 1988 | 21.8 °C |
| 1989 | 20.3 °C |
| 1990 | 21.2 °C |
| 1991 | 22.5 °C |
| 1992 | 20.6 °C |
| 1993 | 21.3 °C |
| 1994 | 20.9 °C |
| 1995 | 21.3 °C |
| 1996 | 20.8 °C |
| 1997 | 19.8 °C |
| 1998 | 21.9 °C |
| 1999 | 21.4 °C |
| 2000 | 20.9 °C |
| 2001 | 21.5 °C |
| 2002 | 21.7 °C |
| 2004 | 20.5 °C |
| 2005 | 21.9 °C |
| 2006 | 21.4 °C |
| 2007 | 21.9 °C |
| 2008 | 20.3 °C |
| 2009 | 20.2 °C |
| 2010 | 22.9 °C |
What this means for you: Since 1970, Cahokia's last spring frost has come about 1 day earlier per decade, on average. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Cahokia (NOAA GHCN-Daily). Years with too many missing days are left out.