When to plant in Denison, IA

Planting dates worked out from Denison's own frost records, not a generic zone chart.

Safe to plant out

May 9

1 year in 10 has a later frost

Average last frost

Apr 24

about a 50% chance of a later one

Average first fall frost

Oct 9

1 year in 10 by Sep 22

Frost-free days

169

median, 1991–2020

Station used: Denison · 3.0 km away · station 427 m, town 391 m. How we match towns to stations

This season

Plan your garden.

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Planting dates for common crops

Crop	Start indoors	Plant out or sow	Harvest from
Tomato	Mar 14 – Mar 28	May 9 – May 23	Jul 3
Sweet pepper	Feb 28 – Mar 14	May 9 – May 23	Jul 8
Lettuce (leaf)	Feb 26 – Mar 5	Apr 2 – Apr 16	May 12
Peas	—	Apr 2 – Apr 30	May 27
Bush beans	—	May 2 – May 23	Jun 21
Carrot	—	Apr 11 – May 23	Jun 10
Beet	—	Apr 11 – May 23	May 31
Potato	—	Apr 11 – May 2	Jun 20
Kale	Feb 26 – Mar 12	Apr 9 – Apr 23	May 22
Broccoli	Feb 19 – Mar 5	Apr 2 – Apr 23	Jun 1
Cucumber	Apr 11 – Apr 18	May 9 – May 23	Jun 28
Summer squash and zucchini	Apr 11 – Apr 18	May 9 – May 23	Jun 23
Winter squash	Apr 11 – Apr 18	May 9 – May 23	Jul 28
Sweet corn	—	May 2 – May 23	Jul 1
Onion (from sets)	—	Apr 2 – Apr 23	Jul 1
Garlic	—	Sep 25 – Oct 23 (fall)	following summer
Spinach	—	Apr 2 – Apr 30	May 10
Basil	Mar 28 – Apr 11	May 9 – May 23	Jul 5

Plan all 65 crops for Denison

Denison'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
1895	May 21
1897	Apr 18
1898	May 5
1899	Apr 22
1900	May 3
1901	May 26
1902	Apr 23
1903	May 3
1904	Apr 28
1905	May 26
1906	May 28
1907	May 27
1908	May 9
1909	May 4
1910	May 13
1911	May 2
1912	May 17
1913	Apr 28
1914	May 13
1915	May 18
1916	May 18
1918	May 13
1919	Apr 26
1920	Apr 28
1921	May 14
1922	Apr 19
1923	May 9
1924	May 24
1925	May 25
1926	May 14
1927	May 5
1928	Apr 27
1929	May 16
1930	Apr 24
1931	May 22
1932	Apr 27
1933	Apr 27
1934	Apr 27
1935	May 5
1936	Apr 22
1937	May 14
1938	May 8
1939	Apr 19
1940	May 1
1941	Apr 24
1942	May 4
1943	May 8
1944	May 6
1945	May 10
1946	May 12
1947	May 29
1948	Apr 13
1949	Apr 24
1950	May 1
1951	Apr 26
1952	Apr 16
1953	May 13
1954	May 8
1955	Apr 7
1956	Apr 30
1957	May 4
1958	Apr 29
1959	May 15
1960	May 11
1961	May 2
1962	Apr 19
1963	May 23
1964	Apr 9
1965	Apr 28
1966	May 9
1967	May 6
1968	May 5
1969	Jun 3
1970	May 2
1971	Apr 29
1972	Apr 25
1973	Apr 27
1974	Apr 23
1975	Apr 20
1976	May 7
1977	Apr 6
1978	May 2
1979	May 3
1980	May 8
1981	May 10
1982	Apr 22
1983	May 15
1984	Apr 30
1985	Apr 9
1986	Apr 22
1987	Apr 5
1988	Apr 27
1989	May 6
1990	May 1
1991	Apr 10
1992	Apr 27
1993	Apr 20
1994	May 1
1995	Apr 27
1996	Apr 30
1997	May 15
1998	Apr 4
1999	Apr 19
2000	Apr 13
2001	Apr 24
2002	Apr 10
2003	Apr 10
2004	May 4
2005	May 4
2006	Apr 9
2007	Apr 15
2008	Apr 30
2009	Apr 15
2010	Apr 18
2011	May 4
2012	Apr 12
2013	May 12
2014	May 17
2015	Apr 23
2016	Apr 13
2017	May 2
2018	Apr 21
2019	Apr 28
2020	May 9
2021	May 12
2022	Apr 27
2023	Apr 24
2024	Apr 20

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1895	131
1897	176
1899	148
1900	136
1901	113
1902	141
1903	146
1904	160
1905	137
1906	124
1907	120
1908	141
1909	159
1910	145
1911	170
1912	131
1913	146
1914	155
1915	125
1916	119
1918	129
1919	166
1920	154
1921	142
1922	172
1923	163
1924	126
1925	134
1926	133
1927	178
1928	150
1929	124
1930	175
1931	147
1932	165
1933	163
1934	152
1935	144
1936	181
1937	124
1938	164
1939	163
1940	147
1941	157
1942	142
1943	134
1944	155
1945	141
1946	139
1947	118
1948	183
1949	157
1950	145
1951	154
1952	171
1953	131
1954	160
1955	190
1956	152
1957	158
1958	154
1959	146
1960	157
1961	148
1962	153
1964	179
1965	148
1966	144
1967	144
1968	151
1969	132
1970	159
1971	181
1972	172
1973	184
1974	151
1975	163
1976	151
1977	185
1978	157
1979	162
1980	131
1981	144
1982	180
1983	128
1984	148
1985	174
1986	173
1987	187
1988	159
1989	139
1990	161
1991	161
1992	170
1993	171
1994	176
1995	147
1996	155
1997	151
1998	212
1999	165
2000	175
2001	164
2002	179
2003	173
2004	150
2005	155
2006	185
2007	152
2008	168
2009	177
2010	192
2011	133
2012	175
2013	159
2014	139
2015	189
2016	182
2017	177
2018	173
2019	166
2020	146
2021	162
2022	153
2023	167
2024	169

Each year's average temperature, April to SeptemberLong-term trend

See the data as a table

Year	Growing-season temperature
1895	18.6 °C
1896	19.6 °C
1897	17.8 °C
1899	17.9 °C
1900	19.2 °C
1901	19.1 °C
1902	16.8 °C
1904	16.9 °C
1905	17.8 °C
1906	18.1 °C
1907	16.2 °C
1908	18.0 °C
1909	17.4 °C
1910	17.8 °C
1911	18.9 °C
1912	18.0 °C
1913	19.1 °C
1914	18.7 °C
1915	17.3 °C
1916	18.3 °C
1918	19.3 °C
1919	18.9 °C
1920	18.0 °C
1921	19.9 °C
1922	19.2 °C
1923	18.1 °C
1924	16.7 °C
1925	19.4 °C
1926	18.4 °C
1927	17.8 °C
1928	17.4 °C
1929	17.8 °C
1930	19.5 °C
1931	20.0 °C
1932	18.9 °C
1933	20.0 °C
1934	20.3 °C
1935	18.2 °C
1936	21.1 °C
1937	19.4 °C
1938	19.2 °C
1939	19.7 °C
1940	18.3 °C
1941	19.6 °C
1942	18.3 °C
1943	17.9 °C
1944	17.9 °C
1945	16.3 °C
1946	17.7 °C
1947	17.9 °C
1948	18.8 °C
1949	18.7 °C
1950	16.2 °C
1951	16.4 °C
1952	18.0 °C
1953	17.9 °C
1954	18.5 °C
1955	20.1 °C
1956	18.1 °C
1957	17.8 °C
1958	17.8 °C
1959	18.5 °C
1960	18.0 °C
1961	16.9 °C
1962	18.0 °C
1963	19.0 °C
1964	18.5 °C
1965	17.9 °C
1966	17.2 °C
1967	17.3 °C
1968	18.0 °C
1969	18.2 °C
1970	18.9 °C
1971	18.5 °C
1972	17.9 °C
1973	18.3 °C
1974	18.1 °C
1975	18.1 °C
1976	19.3 °C
1977	20.2 °C
1978	18.1 °C
1979	17.8 °C
1980	18.9 °C
1981	18.7 °C
1983	17.8 °C
1984	18.2 °C
1985	18.8 °C
1986	19.2 °C
1987	20.4 °C
1988	20.0 °C
1989	18.4 °C
1990	18.3 °C
1991	18.9 °C
1992	16.8 °C
1993	16.8 °C
1994	18.1 °C
1995	18.0 °C
1996	16.7 °C
1997	17.4 °C
1998	18.9 °C
1999	17.6 °C
2000	18.7 °C
2001	18.4 °C
2002	18.6 °C
2003	17.9 °C
2004	17.8 °C
2005	19.2 °C
2006	18.4 °C
2007	18.6 °C
2008	17.5 °C
2009	17.1 °C
2010	18.4 °C
2011	17.1 °C
2012	19.0 °C
2013	16.7 °C
2014	16.7 °C
2015	17.8 °C
2016	18.3 °C
2017	18.0 °C
2018	18.0 °C
2019	17.7 °C
2020	18.4 °C
2021	18.8 °C
2022	18.2 °C
2023	19.2 °C
2024	19.1 °C

What this means for you: Since 1895, Denison's last spring frost has come about 1 day earlier per decade, on average. The frost-free season has grown 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 Denison (NOAA GHCN-Daily). Years with too many missing days are left out.

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