When to plant in Sumner, IA
Planting dates worked out from Sumner's own frost records, not a generic zone chart.
Safe to plant out
May 13
1 year in 10 has a later frost
Average last frost
Apr 29
about a 50% chance of a later one
Average first fall frost
Oct 5
1 year in 10 by Sep 20
Frost-free days
156
median, 1991–2020
Station used: Tripoli · 14.1 km away · station 322 m, town 323 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 18 – Apr 1 | May 13 – May 27 | Jul 7 |
| Sweet pepper | Mar 4 – Mar 18 | May 13 – May 27 | Jul 12 |
| Lettuce (leaf) | Mar 2 – Mar 9 | Apr 6 – Apr 20 | May 16 |
| Peas | — | Apr 6 – May 4 | May 31 |
| Bush beans | — | May 6 – May 27 | Jun 25 |
| Carrot | — | Apr 16 – May 28 | Jun 15 |
| Beet | — | Apr 16 – May 28 | Jun 5 |
| Potato | — | Apr 16 – May 7 | Jun 25 |
| Kale | Mar 2 – Mar 16 | Apr 13 – Apr 27 | May 26 |
| Broccoli | Feb 23 – Mar 9 | Apr 6 – Apr 27 | Jun 5 |
| Cucumber | Apr 15 – Apr 22 | May 13 – May 27 | Jul 2 |
| Summer squash and zucchini | Apr 15 – Apr 22 | May 13 – May 27 | Jun 27 |
| Winter squash | Apr 15 – Apr 22 | May 13 – May 27 | Aug 1 |
| Sweet corn | — | May 6 – May 27 | Jul 5 |
| Onion (from sets) | — | Apr 6 – Apr 27 | Jul 5 |
| Garlic | — | Sep 21 – Oct 19 (fall) | following summer |
| Spinach | — | Apr 6 – May 4 | May 14 |
| Basil | Apr 1 – Apr 15 | May 13 – May 27 | Jul 9 |
Sumner'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 24 |
| 1950 | May 1 |
| 1951 | Apr 26 |
| 1952 | Apr 16 |
| 1953 | May 13 |
| 1954 | May 9 |
| 1956 | May 16 |
| 1957 | May 4 |
| 1958 | May 5 |
| 1959 | Apr 21 |
| 1960 | May 1 |
| 1961 | May 2 |
| 1962 | Apr 20 |
| 1963 | May 22 |
| 1964 | Apr 15 |
| 1965 | May 29 |
| 1966 | May 11 |
| 1967 | May 6 |
| 1968 | May 5 |
| 1969 | Apr 29 |
| 1970 | May 2 |
| 1971 | May 3 |
| 1972 | Apr 25 |
| 1973 | May 3 |
| 1974 | May 6 |
| 1975 | Apr 22 |
| 1976 | May 4 |
| 1977 | Apr 29 |
| 1978 | May 1 |
| 1979 | May 1 |
| 1980 | May 7 |
| 1981 | May 11 |
| 1985 | Apr 10 |
| 1986 | Apr 23 |
| 1987 | Apr 6 |
| 1988 | Apr 29 |
| 1989 | May 8 |
| 1990 | May 2 |
| 1991 | Apr 25 |
| 1992 | May 7 |
| 1993 | Apr 22 |
| 1994 | May 2 |
| 1995 | Apr 28 |
| 1996 | May 2 |
| 1997 | May 16 |
| 1998 | Apr 17 |
| 1999 | Mar 27 |
| 2000 | Apr 13 |
| 2001 | Apr 24 |
| 2002 | May 3 |
| 2004 | May 3 |
| 2005 | May 4 |
| 2007 | Apr 16 |
| 2009 | Apr 20 |
| 2010 | May 9 |
| 2011 | May 5 |
| 2012 | Apr 22 |
| 2013 | May 12 |
| 2014 | May 15 |
| 2015 | Apr 26 |
| 2016 | May 15 |
| 2017 | Apr 29 |
| 2018 | Apr 21 |
| 2019 | Apr 29 |
| 2020 | May 12 |
| 2021 | Apr 26 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1949 | 157 |
| 1950 | 145 |
| 1951 | 154 |
| 1952 | 171 |
| 1953 | 166 |
| 1954 | 160 |
| 1956 | 126 |
| 1957 | 146 |
| 1958 | 148 |
| 1959 | 172 |
| 1960 | 170 |
| 1961 | 148 |
| 1962 | 185 |
| 1963 | 159 |
| 1964 | 165 |
| 1965 | 135 |
| 1966 | 142 |
| 1967 | 145 |
| 1968 | 151 |
| 1969 | 170 |
| 1970 | 154 |
| 1971 | 156 |
| 1972 | 157 |
| 1973 | 179 |
| 1974 | 138 |
| 1975 | 162 |
| 1976 | 142 |
| 1977 | 159 |
| 1978 | 159 |
| 1979 | 156 |
| 1980 | 141 |
| 1981 | 143 |
| 1985 | 173 |
| 1986 | 165 |
| 1987 | 179 |
| 1988 | 157 |
| 1990 | 161 |
| 1991 | 146 |
| 1992 | 144 |
| 1993 | 162 |
| 1994 | 160 |
| 1995 | 146 |
| 1996 | 153 |
| 1997 | 150 |
| 1998 | 185 |
| 1999 | 190 |
| 2000 | 175 |
| 2001 | 164 |
| 2004 | 151 |
| 2005 | 156 |
| 2007 | 151 |
| 2009 | 173 |
| 2011 | 132 |
| 2012 | 153 |
| 2013 | 160 |
| 2014 | 142 |
| 2015 | 172 |
| 2016 | 150 |
| 2017 | 180 |
| 2018 | 173 |
| 2019 | 165 |
| 2020 | 142 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1949 | 18.7 °C |
| 1950 | 16.4 °C |
| 1951 | 16.6 °C |
| 1952 | 18.5 °C |
| 1953 | 17.7 °C |
| 1954 | 18.3 °C |
| 1956 | 17.1 °C |
| 1957 | 17.2 °C |
| 1958 | 16.8 °C |
| 1959 | 18.0 °C |
| 1960 | 18.0 °C |
| 1961 | 16.7 °C |
| 1962 | 17.3 °C |
| 1963 | 18.0 °C |
| 1964 | 18.5 °C |
| 1965 | 17.2 °C |
| 1966 | 16.8 °C |
| 1967 | 16.4 °C |
| 1968 | 17.4 °C |
| 1969 | 17.6 °C |
| 1970 | 18.0 °C |
| 1971 | 17.6 °C |
| 1972 | 17.4 °C |
| 1973 | 17.5 °C |
| 1974 | 16.8 °C |
| 1975 | 17.4 °C |
| 1976 | 17.9 °C |
| 1977 | 19.2 °C |
| 1978 | 18.2 °C |
| 1979 | 17.3 °C |
| 1980 | 18.7 °C |
| 1981 | 18.1 °C |
| 1985 | 17.1 °C |
| 1986 | 17.3 °C |
| 1987 | 18.2 °C |
| 1988 | 18.6 °C |
| 1989 | 16.5 °C |
| 1990 | 16.8 °C |
| 1991 | 17.9 °C |
| 1992 | 15.2 °C |
| 1993 | 15.5 °C |
| 1994 | 16.7 °C |
| 1995 | 16.9 °C |
| 1996 | 16.3 °C |
| 1997 | 16.5 °C |
| 1998 | 18.4 °C |
| 1999 | 17.6 °C |
| 2000 | 17.6 °C |
| 2001 | 17.7 °C |
| 2004 | 17.1 °C |
| 2005 | 18.4 °C |
| 2007 | 18.1 °C |
| 2009 | 16.3 °C |
| 2010 | 18.2 °C |
| 2011 | 17.2 °C |
| 2012 | 18.4 °C |
| 2013 | 16.8 °C |
| 2014 | 16.6 °C |
| 2015 | 17.9 °C |
| 2016 | 18.3 °C |
| 2017 | 17.9 °C |
| 2018 | 17.8 °C |
| 2019 | 17.6 °C |
| 2020 | 17.6 °C |
What this means for you: Since 1949, Sumner'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 Tripoli (NOAA GHCN-Daily). Years with too many missing days are left out.