When to plant in Upper Alton, IL
Planting dates worked out from Upper Alton's own frost records, not a generic zone chart.
Safe to plant out
Apr 11
1 year in 10 has a later frost
Average last frost
Mar 31
about a 50% chance of a later one
Average first fall frost
Nov 8
1 year in 10 by Nov 1
Frost-free days
215
median, 1991–2020
Station used: Alton - Melvin Price L&d · 5.0 km away · station 123 m, town 166 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 14 – Feb 28 | Apr 11 – Apr 25 | Jun 5 |
| Sweet pepper | Jan 31 – Feb 14 | Apr 11 – Apr 25 | Jun 10 |
| Lettuce (leaf) | Feb 5 – Feb 12 | Mar 12 – Mar 26 | Apr 21 |
| Peas | — | Mar 12 – Apr 9 | May 6 |
| Bush beans | — | Apr 4 – Apr 25 | May 24 |
| Carrot | — | Mar 20 – May 1 | May 19 |
| Beet | — | Mar 20 – May 1 | May 9 |
| Potato | — | Mar 20 – Apr 10 | May 29 |
| Kale | Feb 5 – Feb 19 | Mar 19 – Apr 2 | May 1 |
| Broccoli | Jan 29 – Feb 12 | Mar 12 – Apr 2 | May 11 |
| Cucumber | Mar 14 – Mar 21 | Apr 11 – Apr 25 | May 31 |
| Summer squash and zucchini | Mar 14 – Mar 21 | Apr 11 – Apr 25 | May 26 |
| Winter squash | Mar 14 – Mar 21 | Apr 11 – Apr 25 | Jun 30 |
| Sweet corn | — | Apr 4 – Apr 25 | Jun 3 |
| Onion (from sets) | — | Mar 12 – Apr 2 | Jun 10 |
| Garlic | — | Oct 22 – Nov 19 (fall) | following summer |
| Spinach | — | Mar 12 – Apr 9 | Apr 19 |
| Basil | Feb 28 – Mar 14 | Apr 11 – Apr 25 | Jun 7 |
Upper Alton'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 |
|---|---|
| 1949 | Apr 19 |
| 1950 | Apr 15 |
| 1951 | Apr 17 |
| 1952 | Apr 11 |
| 1953 | Apr 21 |
| 1954 | Apr 3 |
| 1955 | Mar 29 |
| 1956 | Apr 24 |
| 1958 | Mar 22 |
| 1959 | Mar 28 |
| 1960 | Apr 10 |
| 1961 | Apr 16 |
| 1962 | Apr 15 |
| 1963 | Mar 22 |
| 1964 | Apr 8 |
| 1965 | Mar 31 |
| 1966 | May 10 |
| 1967 | Mar 19 |
| 1968 | Apr 6 |
| 1969 | Apr 1 |
| 1970 | Apr 5 |
| 1971 | Apr 7 |
| 1972 | Apr 10 |
| 1973 | Apr 13 |
| 1974 | Apr 9 |
| 1975 | Apr 8 |
| 1976 | Apr 14 |
| 1977 | Mar 22 |
| 1978 | Mar 27 |
| 1979 | Apr 7 |
| 1980 | Apr 15 |
| 1981 | Mar 23 |
| 1982 | Apr 10 |
| 1983 | Apr 20 |
| 1985 | Apr 10 |
| 1986 | Apr 22 |
| 1987 | Apr 5 |
| 1988 | Mar 20 |
| 1990 | Apr 8 |
| 1991 | Mar 31 |
| 1992 | Apr 4 |
| 1993 | Apr 2 |
| 1994 | Apr 8 |
| 1995 | Apr 6 |
| 1996 | Apr 6 |
| 1997 | Apr 12 |
| 1998 | Mar 25 |
| 2000 | Apr 12 |
| 2001 | Mar 31 |
| 2002 | Apr 5 |
| 2003 | Mar 12 |
| 2004 | Mar 23 |
| 2005 | Mar 16 |
| 2007 | Apr 9 |
| 2008 | Mar 25 |
| 2009 | Mar 14 |
| 2016 | Apr 10 |
| 2025 | Apr 9 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1949 | 189 |
| 1950 | 202 |
| 1951 | 197 |
| 1952 | 177 |
| 1953 | 197 |
| 1955 | 218 |
| 1956 | 197 |
| 1958 | 248 |
| 1959 | 221 |
| 1960 | 192 |
| 1961 | 203 |
| 1962 | 193 |
| 1963 | 237 |
| 1964 | 224 |
| 1965 | 230 |
| 1966 | 174 |
| 1967 | 229 |
| 1968 | 216 |
| 1970 | 223 |
| 1971 | 213 |
| 1972 | 191 |
| 1973 | 205 |
| 1974 | 218 |
| 1975 | 219 |
| 1976 | 184 |
| 1977 | 233 |
| 1978 | 210 |
| 1979 | 189 |
| 1980 | 193 |
| 1981 | 213 |
| 1983 | 198 |
| 1985 | 174 |
| 1986 | 201 |
| 1987 | 218 |
| 1988 | 224 |
| 1990 | 213 |
| 1991 | 215 |
| 1992 | 197 |
| 1993 | 211 |
| 1994 | 228 |
| 1995 | 210 |
| 1996 | 209 |
| 1997 | 213 |
| 1998 | 226 |
| 2002 | 210 |
| 2003 | 240 |
| 2004 | 234 |
| 2005 | 245 |
| 2008 | 229 |
| 2025 | 206 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1948 | 22.2 °C |
| 1949 | 21.2 °C |
| 1950 | 19.8 °C |
| 1951 | 20.4 °C |
| 1952 | 22.2 °C |
| 1953 | 22.2 °C |
| 1955 | 22.2 °C |
| 1956 | 21.0 °C |
| 1958 | 20.9 °C |
| 1959 | 22.2 °C |
| 1960 | 21.5 °C |
| 1961 | 20.2 °C |
| 1962 | 21.5 °C |
| 1963 | 21.5 °C |
| 1964 | 22.0 °C |
| 1965 | 21.5 °C |
| 1966 | 20.5 °C |
| 1967 | 20.1 °C |
| 1968 | 21.0 °C |
| 1969 | 20.7 °C |
| 1970 | 21.3 °C |
| 1971 | 20.3 °C |
| 1972 | 20.4 °C |
| 1973 | 20.2 °C |
| 1974 | 19.9 °C |
| 1975 | 20.4 °C |
| 1976 | 20.2 °C |
| 1977 | 22.2 °C |
| 1978 | 21.1 °C |
| 1979 | 20.5 °C |
| 1980 | 21.7 °C |
| 1981 | 20.9 °C |
| 1982 | 20.0 °C |
| 1983 | 21.3 °C |
| 1985 | 19.6 °C |
| 1986 | 21.8 °C |
| 1987 | 22.7 °C |
| 1992 | 19.9 °C |
| 1993 | 20.6 °C |
| 1994 | 20.7 °C |
| 1995 | 20.6 °C |
| 1996 | 19.9 °C |
| 1997 | 19.9 °C |
| 1998 | 22.2 °C |
| 2002 | 21.7 °C |
| 2003 | 20.3 °C |
| 2004 | 20.5 °C |
| 2005 | 22.9 °C |
| 2007 | 22.6 °C |
| 2008 | 20.5 °C |
| 2009 | 21.2 °C |
| 2016 | 21.4 °C |
What this means for you: Since 1949, Upper Alton's last spring frost has come about 2 days earlier per decade, on average. The frost-free season has grown by about 3 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Alton - Melvin Price L&d (NOAA GHCN-Daily). Years with too many missing days are left out.