When to plant in Charles City, IA
Planting dates worked out from Charles City's own frost records, not a generic zone chart.
Safe to plant out
May 16
1 year in 10 has a later frost
Average last frost
May 2
about a 50% chance of a later one
Average first fall frost
Oct 3
1 year in 10 by Sep 20
Frost-free days
150
median, 1991–2020
Station used: Charles City · 0.7 km away · station 303 m, town 307 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 21 – Apr 4 | May 16 – May 30 | Jul 10 |
| Sweet pepper | Mar 7 – Mar 21 | May 16 – May 30 | Jul 15 |
| Lettuce (leaf) | Feb 28 – Mar 7 | Apr 4 – Apr 18 | May 14 |
| Peas | — | Apr 3 – May 1 | May 28 |
| Bush beans | — | May 9 – May 30 | Jun 28 |
| Carrot | — | Apr 12 – May 24 | Jun 11 |
| Beet | — | Apr 12 – May 24 | Jun 1 |
| Potato | — | Apr 12 – May 3 | Jun 21 |
| Kale | Feb 27 – Mar 13 | Apr 10 – Apr 24 | May 23 |
| Broccoli | Feb 21 – Mar 7 | Apr 4 – Apr 25 | Jun 3 |
| Cucumber | Apr 18 – Apr 25 | May 16 – May 30 | Jul 5 |
| Summer squash and zucchini | Apr 18 – Apr 25 | May 16 – May 30 | Jun 30 |
| Winter squash | Apr 18 – Apr 25 | May 16 – May 30 | Aug 4 |
| Sweet corn | — | May 9 – May 30 | Jul 8 |
| Onion (from sets) | — | Apr 4 – Apr 25 | Jul 3 |
| Garlic | — | Sep 19 – Oct 17 (fall) | following summer |
| Spinach | — | Apr 3 – May 1 | May 11 |
| Basil | Apr 4 – Apr 18 | May 16 – May 30 | Jul 12 |
Charles City'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 |
|---|---|
| 1893 | May 4 |
| 1895 | May 21 |
| 1896 | Apr 9 |
| 1898 | Apr 29 |
| 1899 | May 13 |
| 1900 | May 5 |
| 1901 | Apr 21 |
| 1903 | May 3 |
| 1904 | May 15 |
| 1949 | Apr 24 |
| 1950 | May 1 |
| 1951 | Apr 26 |
| 1952 | Apr 16 |
| 1953 | May 13 |
| 1954 | May 20 |
| 1955 | Apr 7 |
| 1956 | May 16 |
| 1957 | May 5 |
| 1958 | Apr 29 |
| 1959 | Apr 22 |
| 1960 | May 12 |
| 1961 | May 3 |
| 1962 | Apr 20 |
| 1963 | May 23 |
| 1964 | Apr 15 |
| 1965 | Apr 28 |
| 1966 | May 11 |
| 1967 | May 6 |
| 1968 | May 5 |
| 1969 | May 12 |
| 1970 | May 2 |
| 1971 | May 3 |
| 1972 | Apr 26 |
| 1973 | May 3 |
| 1974 | May 6 |
| 1975 | Apr 22 |
| 1976 | May 4 |
| 1977 | Apr 8 |
| 1978 | May 2 |
| 1979 | Apr 30 |
| 1980 | Apr 24 |
| 1981 | May 10 |
| 1982 | Apr 22 |
| 1983 | May 8 |
| 1984 | Apr 30 |
| 1985 | Apr 15 |
| 1986 | Apr 22 |
| 1987 | Apr 6 |
| 1988 | Apr 29 |
| 1989 | May 7 |
| 1990 | May 2 |
| 1991 | Apr 24 |
| 1992 | May 6 |
| 1993 | Apr 21 |
| 1994 | May 2 |
| 1995 | Apr 27 |
| 1996 | May 13 |
| 1997 | May 16 |
| 1998 | Apr 17 |
| 1999 | May 9 |
| 2000 | Apr 22 |
| 2001 | Apr 24 |
| 2002 | Apr 26 |
| 2003 | Apr 10 |
| 2004 | May 15 |
| 2005 | May 16 |
| 2006 | May 6 |
| 2007 | Apr 16 |
| 2008 | Apr 29 |
| 2009 | May 17 |
| 2010 | May 9 |
| 2011 | May 4 |
| 2012 | Apr 21 |
| 2013 | May 12 |
| 2014 | May 17 |
| 2015 | Apr 28 |
| 2016 | May 15 |
| 2017 | Apr 28 |
| 2018 | Apr 29 |
| 2019 | Apr 28 |
| 2020 | May 12 |
| 2021 | May 11 |
| 2022 | May 4 |
| 2023 | May 3 |
| 2024 | Apr 24 |
| 2025 | Apr 16 |
| 2026 | May 7 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1893 | 143 |
| 1895 | 131 |
| 1896 | 163 |
| 1898 | 159 |
| 1899 | 135 |
| 1900 | 155 |
| 1901 | 164 |
| 1903 | 137 |
| 1949 | 157 |
| 1950 | 155 |
| 1951 | 154 |
| 1952 | 169 |
| 1953 | 146 |
| 1954 | 150 |
| 1955 | 157 |
| 1956 | 136 |
| 1957 | 157 |
| 1958 | 154 |
| 1959 | 172 |
| 1960 | 159 |
| 1961 | 147 |
| 1962 | 183 |
| 1963 | 157 |
| 1964 | 165 |
| 1965 | 167 |
| 1966 | 142 |
| 1967 | 144 |
| 1968 | 151 |
| 1969 | 154 |
| 1970 | 154 |
| 1971 | 156 |
| 1972 | 156 |
| 1973 | 179 |
| 1974 | 138 |
| 1975 | 156 |
| 1976 | 142 |
| 1977 | 186 |
| 1978 | 158 |
| 1979 | 157 |
| 1980 | 154 |
| 1981 | 144 |
| 1982 | 176 |
| 1983 | 137 |
| 1984 | 147 |
| 1985 | 168 |
| 1986 | 166 |
| 1987 | 179 |
| 1988 | 156 |
| 1989 | 138 |
| 1990 | 160 |
| 1991 | 147 |
| 1992 | 145 |
| 1993 | 160 |
| 1994 | 160 |
| 1995 | 147 |
| 1996 | 142 |
| 1997 | 150 |
| 1998 | 173 |
| 1999 | 134 |
| 2000 | 151 |
| 2001 | 164 |
| 2002 | 161 |
| 2003 | 171 |
| 2004 | 139 |
| 2005 | 144 |
| 2006 | 136 |
| 2007 | 151 |
| 2008 | 157 |
| 2009 | 144 |
| 2010 | 146 |
| 2011 | 133 |
| 2012 | 154 |
| 2013 | 159 |
| 2014 | 145 |
| 2015 | 171 |
| 2016 | 150 |
| 2017 | 181 |
| 2018 | 165 |
| 2019 | 166 |
| 2020 | 142 |
| 2021 | 163 |
| 2022 | 146 |
| 2023 | 159 |
| 2024 | 173 |
| 2025 | 189 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1893 | 17.2 °C |
| 1894 | 18.5 °C |
| 1895 | 18.4 °C |
| 1896 | 18.7 °C |
| 1898 | 17.2 °C |
| 1899 | 17.8 °C |
| 1900 | 18.6 °C |
| 1901 | 18.5 °C |
| 1903 | 16.2 °C |
| 1904 | 15.6 °C |
| 1949 | 18.2 °C |
| 1950 | 15.8 °C |
| 1951 | 16.0 °C |
| 1952 | 17.7 °C |
| 1953 | 17.5 °C |
| 1954 | 18.3 °C |
| 1955 | 19.8 °C |
| 1956 | 17.7 °C |
| 1957 | 18.0 °C |
| 1958 | 17.5 °C |
| 1959 | 18.6 °C |
| 1960 | 18.0 °C |
| 1961 | 16.9 °C |
| 1962 | 17.2 °C |
| 1963 | 18.0 °C |
| 1964 | 18.2 °C |
| 1965 | 17.1 °C |
| 1966 | 16.7 °C |
| 1967 | 16.4 °C |
| 1968 | 17.4 °C |
| 1969 | 17.6 °C |
| 1970 | 18.1 °C |
| 1971 | 17.7 °C |
| 1972 | 17.4 °C |
| 1973 | 17.6 °C |
| 1974 | 17.2 °C |
| 1975 | 17.5 °C |
| 1976 | 18.1 °C |
| 1977 | 19.5 °C |
| 1978 | 18.2 °C |
| 1979 | 16.9 °C |
| 1980 | 18.6 °C |
| 1981 | 17.8 °C |
| 1982 | 17.0 °C |
| 1983 | 17.7 °C |
| 1984 | 17.5 °C |
| 1985 | 18.1 °C |
| 1986 | 18.1 °C |
| 1987 | 19.1 °C |
| 1988 | 19.0 °C |
| 1989 | 17.3 °C |
| 1990 | 17.3 °C |
| 1991 | 18.4 °C |
| 1992 | 16.1 °C |
| 1993 | 16.1 °C |
| 1994 | 17.2 °C |
| 1995 | 17.3 °C |
| 1996 | 16.3 °C |
| 1997 | 16.3 °C |
| 1998 | 18.7 °C |
| 1999 | 17.6 °C |
| 2000 | 17.2 °C |
| 2001 | 18.7 °C |
| 2003 | 18.0 °C |
| 2004 | 17.5 °C |
| 2005 | 18.8 °C |
| 2006 | 18.4 °C |
| 2007 | 18.1 °C |
| 2008 | 16.8 °C |
| 2009 | 16.3 °C |
| 2010 | 18.5 °C |
| 2011 | 17.3 °C |
| 2012 | 18.7 °C |
| 2013 | 17.0 °C |
| 2014 | 16.8 °C |
| 2015 | 17.7 °C |
| 2016 | 17.9 °C |
| 2017 | 17.5 °C |
| 2018 | 17.3 °C |
| 2019 | 17.4 °C |
| 2020 | 17.2 °C |
| 2021 | 18.2 °C |
| 2022 | 17.3 °C |
| 2023 | 18.2 °C |
| 2024 | 17.9 °C |
| 2025 | 17.9 °C |
| 2026 | 18.8 °C |
What this means for you: Since 1893, Charles City's last spring frost has stayed at about the same time of year. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Charles City (NOAA GHCN-Daily). Years with too many missing days are left out.