When to plant in Harlan, IA

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

Safe to plant out

May 11

1 year in 10 has a later frost

Average last frost

Apr 26

about a 50% chance of a later one

Average first fall frost

Oct 9

1 year in 10 by Sep 22

Frost-free days

165

median, 1991–2020

Station used: Harlan · 1.1 km away · station 387 m, town 382 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 16 – Mar 30	May 11 – May 25	Jul 5
Sweet pepper	Mar 2 – Mar 16	May 11 – May 25	Jul 10
Lettuce (leaf)	Feb 22 – Mar 1	Mar 29 – Apr 12	May 8
Peas	—	Mar 28 – Apr 25	May 22
Bush beans	—	May 4 – May 25	Jun 23
Carrot	—	Apr 6 – May 18	Jun 5
Beet	—	Apr 6 – May 18	May 26
Potato	—	Apr 6 – Apr 27	Jun 15
Kale	Feb 21 – Mar 7	Apr 4 – Apr 18	May 17
Broccoli	Feb 15 – Mar 1	Mar 29 – Apr 19	May 28
Cucumber	Apr 13 – Apr 20	May 11 – May 25	Jun 30
Summer squash and zucchini	Apr 13 – Apr 20	May 11 – May 25	Jun 25
Winter squash	Apr 13 – Apr 20	May 11 – May 25	Jul 30
Sweet corn	—	May 4 – May 25	Jul 3
Onion (from sets)	—	Mar 29 – Apr 19	Jun 27
Garlic	—	Sep 25 – Oct 23 (fall)	following summer
Spinach	—	Mar 28 – Apr 25	May 5
Basil	Mar 30 – Apr 13	May 11 – May 25	Jul 7

Plan all 65 crops for Harlan

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

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1899	162
1900	136
1901	127
1902	141
1903	135
1904	176
1905	137
1906	144
1907	131
1908	141
1909	153
1910	136
1911	170
1912	131
1913	147
1914	164
1915	140
1916	119
1918	129
1919	166
1922	171
1925	133
1926	133
1927	164
1928	150
1929	121
1930	175
1931	147
1932	154
1933	152
1934	152
1935	151
1936	170
1937	124
1938	180
1939	163
1940	165
1941	174
1942	142
1943	144
1944	156
1945	142
1946	152
1947	152
1948	185
1949	162
1950	155
1951	154
1952	169
1953	147
1954	163
1955	183
1956	152
1957	178
1958	154
1959	146
1960	167
1961	148
1962	186
1963	157
1964	171
1965	148
1966	143
1967	135
1968	148
1969	132
1970	159
1971	159
1972	157
1973	166
1974	164
1975	164
1976	150
1977	185
1978	156
1979	153
1980	146
1981	143
1982	175
1983	130
1984	148
1985	174
1986	173
1987	176
1988	158
1989	138
1990	162
1991	161
1992	157
1993	170
1994	176
1995	142
1996	179
1997	153
1998	200
1999	156
2000	175
2001	163
2002	167
2003	168
2004	150
2005	147
2006	184
2007	193
2008	168
2009	174
2010	146
2011	167
2012	163
2013	153
2014	146

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

See the data as a table

Year	Growing-season temperature
1899	18.4 °C
1900	19.1 °C
1901	19.5 °C
1902	17.5 °C
1903	17.2 °C
1904	16.9 °C
1905	17.9 °C
1906	18.3 °C
1907	16.5 °C
1908	18.0 °C
1909	17.5 °C
1910	17.8 °C
1911	19.1 °C
1912	17.7 °C
1913	19.1 °C
1914	19.1 °C
1915	17.3 °C
1916	17.9 °C
1917	16.8 °C
1918	18.7 °C
1919	18.6 °C
1921	19.9 °C
1922	19.1 °C
1925	19.3 °C
1926	18.6 °C
1927	17.6 °C
1928	17.0 °C
1929	17.6 °C
1930	19.0 °C
1931	20.0 °C
1932	19.2 °C
1933	19.8 °C
1934	20.5 °C
1935	18.4 °C
1936	21.0 °C
1937	19.7 °C
1938	19.6 °C
1939	20.2 °C
1940	18.8 °C
1941	20.2 °C
1942	18.9 °C
1943	18.7 °C
1944	18.8 °C
1945	17.4 °C
1946	18.8 °C
1947	18.9 °C
1948	19.9 °C
1949	18.9 °C
1950	17.1 °C
1951	17.2 °C
1952	19.0 °C
1953	19.2 °C
1954	19.9 °C
1955	20.9 °C
1956	19.4 °C
1957	18.9 °C
1958	18.7 °C
1959	19.3 °C
1960	18.8 °C
1961	17.6 °C
1962	18.9 °C
1963	19.6 °C
1964	18.9 °C
1965	18.3 °C
1966	17.5 °C
1967	17.4 °C
1968	18.3 °C
1969	18.6 °C
1970	19.2 °C
1971	18.6 °C
1972	18.3 °C
1973	18.3 °C
1974	18.1 °C
1975	18.4 °C
1976	18.8 °C
1977	20.1 °C
1978	18.9 °C
1979	18.1 °C
1980	19.6 °C
1981	19.1 °C
1982	17.9 °C
1983	18.7 °C
1984	18.1 °C
1985	18.4 °C
1986	19.3 °C
1987	19.8 °C
1988	20.4 °C
1989	18.8 °C
1990	18.8 °C
1991	19.5 °C
1992	17.2 °C
1993	17.7 °C
1994	18.9 °C
1995	18.4 °C
1996	18.1 °C
1997	18.5 °C
1998	20.3 °C
1999	17.7 °C
2000	18.7 °C
2001	18.8 °C
2002	18.7 °C
2003	18.0 °C
2004	17.7 °C
2005	19.4 °C
2006	18.9 °C
2007	19.1 °C
2008	17.5 °C
2009	17.1 °C
2010	19.2 °C
2011	18.1 °C
2012	19.6 °C
2013	17.3 °C
2014	18.6 °C

What this means for you: Since 1899, Harlan'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 Harlan (NOAA GHCN-Daily). Years with too many missing days are left out.

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