When to plant in Rockwell, IA

Planting dates worked out from Rockwell'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 3

about a 50% chance of a later one

Average first fall frost

Oct 5

1 year in 10 by Sep 20

Frost-free days

155

median, 1991–2020

Station used: Mason City · 19.8 km away · station 337 m, town 340 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 21 – Apr 4	May 16 – May 30	Jul 10
Sweet pepper	Mar 7 – Mar 21	May 16 – May 30	Jul 15
Lettuce (leaf)	Mar 5 – Mar 12	Apr 9 – Apr 23	May 19
Peas	—	Apr 9 – May 7	Jun 3
Bush beans	—	May 9 – May 30	Jun 28
Carrot	—	Apr 19 – May 31	Jun 18
Beet	—	Apr 19 – May 31	Jun 8
Potato	—	Apr 19 – May 10	Jun 28
Kale	Mar 5 – Mar 19	Apr 16 – Apr 30	May 29
Broccoli	Feb 26 – Mar 12	Apr 9 – Apr 30	Jun 8
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 9 – Apr 30	Jul 8
Garlic	—	Sep 21 – Oct 19 (fall)	following summer
Spinach	—	Apr 9 – May 7	May 17
Basil	Apr 4 – Apr 18	May 16 – May 30	Jul 12

Plan all 65 crops for Rockwell

Rockwell'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
1898	May 6
1903	May 3
1904	Apr 21
1905	Apr 30
1906	May 7
1907	May 27
1908	May 3
1909	May 10
1910	May 14
1911	May 5
1912	Apr 27
1913	May 10
1914	May 15
1915	May 9
1916	May 2
1917	May 23
1918	May 13
1919	May 2
1920	May 15
1921	May 16
1922	Apr 29
1923	May 17
1924	May 24
1925	May 25
1926	May 3
1927	Apr 24
1928	Jun 2
1929	May 19
1930	May 30
1931	May 23
1932	May 2
1933	Apr 27
1934	May 25
1935	May 4
1936	Apr 26
1937	May 14
1938	May 12
1939	May 13
1940	May 15
1941	Apr 24
1942	May 16
1943	May 14
1944	May 6
1945	May 10
1946	May 12
1947	May 29
1948	Apr 21
1949	Apr 24
1950	May 7
1951	Apr 26
1952	Apr 24
1953	May 13
1954	May 20
1955	May 8
1956	May 16
1957	May 5
1958	May 5
1959	Apr 22
1960	May 12
1961	May 26
1962	Apr 19
1963	May 23
1964	Apr 15
1965	Apr 28
1966	May 14
1967	May 13
1968	May 12
1969	May 12
1970	May 2
1971	May 12
1972	Apr 26
1974	May 6
1975	Apr 21
1976	May 8
1977	Apr 8
1979	May 12
1981	May 19
1982	Apr 28
1983	May 15
1984	Apr 30
1985	Apr 15
1986	May 3
1987	Apr 6
1988	Apr 27
1989	May 8
1990	May 3
1991	May 20
1992	May 7
1993	Apr 27
1994	May 3
1995	Apr 23
1996	May 1
1997	May 16
1998	Apr 28
1999	Apr 19
2000	Apr 22
2001	Apr 24
2002	May 4
2003	Apr 23
2004	May 15
2005	May 5
2006	May 7
2007	Apr 17
2008	Apr 30
2009	May 17
2010	May 10
2011	May 4
2012	Apr 18
2013	May 12
2014	May 17
2015	Apr 27
2016	May 15
2017	Apr 29
2018	Apr 21
2019	Apr 29
2020	May 10
2021	May 11
2022	Apr 28
2023	May 4
2024	Apr 23
2025	May 1
2026	May 2

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1898	152
1903	173
1904	167
1905	163
1906	154
1907	120
1908	147
1909	154
1910	144
1911	155
1912	151
1913	134
1914	162
1915	112
1916	137
1917	140
1919	161
1920	137
1921	139
1922	162
1923	119
1924	128
1925	134
1926	144
1927	148
1929	121
1930	120
1931	141
1932	149
1933	157
1934	154
1935	145
1936	158
1937	124
1938	163
1939	135
1940	132
1941	157
1942	126
1943	125
1944	155
1945	141
1946	139
1947	115
1948	171
1949	157
1950	139
1951	151
1952	151
1953	122
1954	124
1955	126
1956	136
1957	157
1958	148
1959	169
1960	159
1961	124
1962	153
1963	158
1964	172
1965	166
1966	134
1967	137
1968	144
1969	154
1970	160
1971	168
1972	156
1974	119
1976	138
1979	145
1981	135
1982	145
1983	128
1985	168
1986	155
1987	179
1988	159
1989	137
1990	159
1991	122
1992	141
1993	157
1994	159
1995	149
1996	154
1997	150
1998	162
1999	154
2000	166
2001	164
2002	155
2003	159
2004	139
2005	155
2006	157
2007	150
2008	168
2009	145
2010	145
2011	134
2012	157
2013	157
2014	139
2015	172
2016	150
2017	180
2018	173
2019	165
2020	144
2021	163
2022	153
2023	159
2024	174
2025	174

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

See the data as a table

Year	Growing-season temperature
1894	18.4 °C
1895	17.7 °C
1898	16.8 °C
1903	17.2 °C
1904	16.5 °C
1905	17.4 °C
1906	18.2 °C
1907	15.8 °C
1908	16.6 °C
1909	15.8 °C
1910	16.8 °C
1911	17.5 °C
1912	16.5 °C
1913	17.9 °C
1914	17.5 °C
1915	16.0 °C
1916	16.9 °C
1917	16.2 °C
1919	17.5 °C
1920	16.4 °C
1921	18.9 °C
1922	17.9 °C
1923	17.7 °C
1924	15.3 °C
1925	17.7 °C
1926	16.8 °C
1927	16.2 °C
1929	16.3 °C
1930	17.2 °C
1931	18.3 °C
1932	16.7 °C
1933	18.3 °C
1934	18.6 °C
1935	16.7 °C
1936	18.6 °C
1937	17.8 °C
1938	17.6 °C
1939	18.2 °C
1940	17.0 °C
1941	18.7 °C
1942	17.1 °C
1943	16.6 °C
1944	17.3 °C
1945	15.5 °C
1946	16.6 °C
1947	16.9 °C
1948	18.2 °C
1949	17.9 °C
1950	15.4 °C
1951	15.6 °C
1952	17.3 °C
1953	16.8 °C
1954	17.2 °C
1955	19.3 °C
1956	16.8 °C
1957	17.2 °C
1958	16.8 °C
1959	18.0 °C
1960	17.1 °C
1961	16.1 °C
1962	16.6 °C
1963	17.8 °C
1964	17.8 °C
1965	16.7 °C
1966	16.3 °C
1967	15.9 °C
1968	16.8 °C
1969	17.1 °C
1970	17.8 °C
1971	17.3 °C
1972	17.0 °C
1974	17.4 °C
1976	17.8 °C
1977	19.7 °C
1979	17.1 °C
1981	17.5 °C
1982	16.9 °C
1983	17.1 °C
1985	17.9 °C
1986	17.7 °C
1987	19.6 °C
1988	19.5 °C
1989	16.6 °C
1990	16.5 °C
1991	17.4 °C
1992	14.9 °C
1993	14.7 °C
1994	16.4 °C
1995	16.4 °C
1996	15.2 °C
1997	15.7 °C
1998	18.0 °C
1999	17.1 °C
2000	16.8 °C
2001	16.9 °C
2002	17.1 °C
2003	16.6 °C
2004	16.2 °C
2005	17.6 °C
2006	17.4 °C
2007	17.2 °C
2008	16.4 °C
2009	15.8 °C
2010	18.0 °C
2011	16.8 °C
2012	18.2 °C
2013	16.4 °C
2014	16.2 °C
2016	17.4 °C
2017	17.5 °C
2018	17.2 °C
2019	17.1 °C
2020	17.2 °C
2021	18.1 °C
2022	17.1 °C
2023	18.1 °C
2024	17.9 °C
2025	17.5 °C
2026	18.3 °C

What this means for you: Since 1895, Rockwell's last spring frost has come about 1 day earlier per decade, on average. The frost-free season has grown by about 1 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.

Source: daily records from Mason City (NOAA GHCN-Daily). Years with too many missing days are left out.

Nearby towns

Sheffield Mason City Clear Lake Nora Springs Hampton Greene