When to plant in Naperville, IL
Planting dates worked out from Naperville's own frost records, not a generic zone chart.
Safe to plant out
May 22
1 year in 10 has a later frost
Average last frost
May 3
about a 50% chance of a later one
Average first fall frost
Oct 9
1 year in 10 by Sep 28
Frost-free days
156
median, 1991–2020
Station used: Wheaton 3 Se · 6.9 km away · station 207 m, town 216 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 | Mar 27 – Apr 10 | May 22 – Jun 5 | Jul 16 |
| Sweet pepper | Mar 13 – Mar 27 | May 22 – Jun 5 | Jul 21 |
| Lettuce (leaf) | Mar 1 – Mar 8 | Apr 5 – Apr 19 | May 15 |
| Peas | — | Mar 26 – Apr 23 | May 20 |
| Bush beans | — | May 15 – Jun 5 | Jul 4 |
| Carrot | — | Apr 12 – May 24 | Jun 11 |
| Beet | — | Apr 5 – May 17 | May 25 |
| Potato | — | Apr 12 – May 3 | Jun 21 |
| Kale | Feb 22 – Mar 8 | Apr 5 – Apr 19 | May 18 |
| Broccoli | Feb 22 – Mar 8 | Apr 5 – Apr 26 | Jun 4 |
| Cucumber | Apr 24 – May 1 | May 22 – Jun 5 | Jul 11 |
| Summer squash and zucchini | Apr 24 – May 1 | May 22 – Jun 5 | Jul 6 |
| Winter squash | Apr 24 – May 1 | May 22 – Jun 5 | Aug 10 |
| Sweet corn | — | May 15 – Jun 5 | Jul 14 |
| Onion (from sets) | — | Apr 5 – Apr 26 | Jul 4 |
| Garlic | — | Sep 25 – Oct 23 (fall) | following summer |
| Spinach | — | Mar 26 – Apr 23 | May 3 |
| Basil | Apr 10 – Apr 24 | May 22 – Jun 5 | Jul 18 |
Naperville'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 |
|---|---|
| 1937 | Apr 11 |
| 1938 | May 13 |
| 1939 | May 3 |
| 1940 | May 4 |
| 1941 | Apr 24 |
| 1942 | Apr 20 |
| 1943 | May 9 |
| 1944 | May 5 |
| 1945 | May 11 |
| 1946 | May 17 |
| 1951 | Apr 23 |
| 1952 | Apr 11 |
| 1953 | Apr 21 |
| 1954 | May 8 |
| 1955 | Apr 8 |
| 1956 | Apr 24 |
| 1957 | May 4 |
| 1958 | Apr 29 |
| 1959 | Apr 22 |
| 1960 | May 12 |
| 1961 | May 1 |
| 1962 | Apr 20 |
| 1963 | May 1 |
| 1964 | Apr 9 |
| 1965 | Apr 3 |
| 1966 | May 11 |
| 1967 | May 16 |
| 1968 | May 6 |
| 1969 | Apr 30 |
| 1970 | May 6 |
| 1971 | May 28 |
| 1972 | Jun 11 |
| 1973 | May 5 |
| 1974 | May 10 |
| 1975 | May 13 |
| 1976 | May 8 |
| 1977 | May 10 |
| 1978 | May 6 |
| 1980 | May 9 |
| 1981 | May 20 |
| 1982 | Apr 28 |
| 1983 | May 16 |
| 1984 | May 16 |
| 1985 | Apr 10 |
| 1986 | May 3 |
| 1987 | Apr 9 |
| 1988 | Apr 29 |
| 1989 | May 12 |
| 1990 | Apr 18 |
| 1991 | Apr 22 |
| 1992 | May 28 |
| 1993 | Apr 27 |
| 1994 | Apr 23 |
| 1995 | Apr 24 |
| 1996 | May 14 |
| 1997 | May 22 |
| 1998 | Apr 28 |
| 1999 | Apr 25 |
| 2000 | Apr 26 |
| 2001 | Apr 19 |
| 2002 | May 21 |
| 2003 | May 4 |
| 2004 | May 3 |
| 2005 | May 5 |
| 2006 | Apr 26 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1937 | 184 |
| 1939 | 163 |
| 1940 | 164 |
| 1941 | 186 |
| 1942 | 157 |
| 1943 | 162 |
| 1944 | 163 |
| 1945 | 141 |
| 1951 | 178 |
| 1952 | 174 |
| 1953 | 168 |
| 1954 | 164 |
| 1955 | 196 |
| 1956 | 148 |
| 1957 | 168 |
| 1958 | 154 |
| 1959 | 172 |
| 1960 | 160 |
| 1961 | 153 |
| 1962 | 186 |
| 1963 | 184 |
| 1964 | 179 |
| 1966 | 142 |
| 1967 | 148 |
| 1968 | 150 |
| 1969 | 166 |
| 1970 | 162 |
| 1971 | 118 |
| 1972 | 125 |
| 1973 | 164 |
| 1974 | 134 |
| 1975 | 155 |
| 1976 | 136 |
| 1977 | 155 |
| 1980 | 148 |
| 1981 | 135 |
| 1982 | 171 |
| 1983 | 163 |
| 1985 | 174 |
| 1987 | 181 |
| 1988 | 159 |
| 1989 | 144 |
| 1990 | 175 |
| 1991 | 157 |
| 1992 | 141 |
| 1993 | 155 |
| 1994 | 169 |
| 1995 | 151 |
| 1996 | 149 |
| 1997 | 145 |
| 1998 | 176 |
| 1999 | 171 |
| 2000 | 163 |
| 2001 | 169 |
| 2002 | 144 |
| 2004 | 152 |
| 2005 | 170 |
| 2006 | 156 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1938 | 18.9 °C |
| 1939 | 18.9 °C |
| 1940 | 17.7 °C |
| 1941 | 19.3 °C |
| 1942 | 18.2 °C |
| 1944 | 19.2 °C |
| 1945 | 16.9 °C |
| 1946 | 17.9 °C |
| 1951 | 17.5 °C |
| 1952 | 19.2 °C |
| 1953 | 18.7 °C |
| 1954 | 18.9 °C |
| 1955 | 20.1 °C |
| 1956 | 18.3 °C |
| 1957 | 18.0 °C |
| 1958 | 17.8 °C |
| 1959 | 19.6 °C |
| 1960 | 18.6 °C |
| 1961 | 17.6 °C |
| 1962 | 18.3 °C |
| 1963 | 18.3 °C |
| 1964 | 19.0 °C |
| 1965 | 18.2 °C |
| 1966 | 17.4 °C |
| 1967 | 16.9 °C |
| 1968 | 18.2 °C |
| 1969 | 18.0 °C |
| 1970 | 18.9 °C |
| 1971 | 18.6 °C |
| 1972 | 17.7 °C |
| 1973 | 18.4 °C |
| 1974 | 17.6 °C |
| 1975 | 17.9 °C |
| 1976 | 17.9 °C |
| 1977 | 19.7 °C |
| 1978 | 19.0 °C |
| 1980 | 18.5 °C |
| 1981 | 18.4 °C |
| 1982 | 17.5 °C |
| 1983 | 18.8 °C |
| 1984 | 18.2 °C |
| 1985 | 19.0 °C |
| 1987 | 20.1 °C |
| 1988 | 20.1 °C |
| 1989 | 18.1 °C |
| 1990 | 18.5 °C |
| 1991 | 20.4 °C |
| 1992 | 17.4 °C |
| 1993 | 18.6 °C |
| 1994 | 19.0 °C |
| 1995 | 19.4 °C |
| 1996 | 17.6 °C |
| 1997 | 18.1 °C |
| 1998 | 20.2 °C |
| 1999 | 19.9 °C |
| 2000 | 19.3 °C |
| 2001 | 19.9 °C |
| 2002 | 19.8 °C |
| 2003 | 17.9 °C |
| 2004 | 18.3 °C |
| 2005 | 19.9 °C |
| 2006 | 18.8 °C |
What this means for you: Since 1937, Naperville's last spring frost has stayed at about the same time of year. The frost-free season has shrunk by about 2 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Wheaton 3 Se (NOAA GHCN-Daily). Years with too many missing days are left out.