When to plant in Marengo, IA

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

Safe to plant out

May 14

1 year in 10 has a later frost

Average last frost

Apr 28

about a 50% chance of a later one

Average first fall frost

Oct 7

1 year in 10 by Sep 23

Frost-free days

161

median, 1991–2020

Station used: Williamsburg 1e · 16.0 km away · station 238 m, town 225 m. How we match towns to stations

This season

Plan your garden.

Build my Marengo plan

Planting dates for common crops

Crop	Start indoors	Plant out or sow	Harvest from
Tomato	Mar 19 – Apr 2	May 14 – May 28	Jul 8
Sweet pepper	Mar 5 – Mar 19	May 14 – May 28	Jul 13
Lettuce (leaf)	Feb 24 – Mar 3	Mar 31 – Apr 14	May 10
Peas	—	Mar 31 – Apr 28	May 25
Bush beans	—	May 7 – May 28	Jun 26
Carrot	—	Apr 9 – May 21	Jun 8
Beet	—	Apr 9 – May 21	May 29
Potato	—	Apr 9 – Apr 30	Jun 18
Kale	Feb 24 – Mar 10	Apr 7 – Apr 21	May 20
Broccoli	Feb 17 – Mar 3	Mar 31 – Apr 21	May 30
Cucumber	Apr 16 – Apr 23	May 14 – May 28	Jul 3
Summer squash and zucchini	Apr 16 – Apr 23	May 14 – May 28	Jun 28
Winter squash	Apr 16 – Apr 23	May 14 – May 28	Aug 2
Sweet corn	—	May 7 – May 28	Jul 6
Onion (from sets)	—	Mar 31 – Apr 21	Jun 29
Garlic	—	Sep 23 – Oct 21 (fall)	following summer
Spinach	—	Mar 31 – Apr 28	May 8
Basil	Apr 2 – Apr 16	May 14 – May 28	Jul 10

Plan all 65 crops for Marengo

Marengo'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
1916	May 2
1917	May 23
1918	May 1
1919	Apr 26
1920	Apr 17
1921	May 3
1922	Apr 29
1923	May 9
1924	May 20
1925	May 26
1926	May 15
1927	Apr 24
1928	May 12
1929	May 21
1930	Apr 25
1931	May 7
1932	May 2
1933	Apr 27
1934	Apr 27
1935	May 4
1936	Apr 23
1937	May 20
1938	Apr 22
1939	Apr 19
1940	Apr 18
1941	Apr 2
1942	Apr 19
1943	Apr 21
1944	May 5
1945	May 9
1946	May 11
1947	May 9
1948	Apr 14
1949	Apr 24
1950	May 1
1953	May 13
1954	May 20
1955	Apr 8
1956	May 16
1957	May 4
1958	May 7
1959	Apr 22
1960	Apr 18
1961	May 10
1962	Apr 16
1963	May 23
1964	Apr 15
1965	Apr 27
1966	May 11
1967	May 7
1968	Apr 25
1969	Apr 29
1970	May 2
1971	May 3
1972	Apr 26
1973	May 15
1974	Apr 24
1975	Apr 13
1976	May 8
1977	Apr 29
1978	May 2
1979	May 1
1980	May 9
1981	Apr 20
1982	Apr 21
1983	May 5
1984	Apr 19
1985	Apr 9
1986	Apr 22
1987	Apr 7
1988	Apr 28
1989	May 7
1990	Apr 19
1991	Apr 11
1992	May 27
1993	Apr 22
1994	Apr 29
1995	Apr 26
1996	May 2
1997	May 16
1998	Apr 19
1999	Mar 29
2000	Apr 13
2001	Apr 19
2002	Apr 27
2003	May 21
2004	May 4
2006	May 6
2007	Apr 15
2009	Apr 22
2010	May 9
2011	May 5
2012	Apr 21
2013	May 13
2016	Apr 13
2017	May 3
2018	Apr 29
2019	Apr 28
2020	May 12
2021	May 12
2022	Apr 20
2023	May 3
2024	Apr 21
2025	Apr 13
2026	May 7

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1895	131
1916	138
1917	110
1918	142
1919	167
1920	166
1921	157
1922	163
1923	150
1924	132
1925	133
1926	132
1927	166
1928	133
1930	174
1931	178
1932	155
1933	173
1934	152
1935	152
1936	181
1937	140
1938	183
1939	177
1940	160
1941	208
1942	157
1943	178
1944	159
1945	152
1946	184
1947	180
1948	185
1949	157
1950	155
1953	131
1954	149
1955	156
1956	126
1958	146
1959	172
1960	183
1961	140
1962	156
1963	158
1964	165
1965	167
1966	147
1967	144
1968	161
1969	167
1970	166
1971	156
1972	156
1973	167
1974	150
1975	165
1976	150
1977	165
1978	158
1979	158
1980	155
1981	164
1982	181
1983	140
1984	159
1985	174
1986	166
1987	178
1988	158
1989	149
1990	182
1992	124
1993	165
1994	163
1995	148
1996	161
1997	151
1998	183
1999	198
2000	175
2001	169
2003	130
2006	158
2007	153
2009	165
2010	146
2011	132
2012	154
2013	152
2016	182
2017	174
2018	165
2019	166
2020	142
2021	162
2022	160
2023	159
2024	176
2025	192

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

See the data as a table

Year	Growing-season temperature
1895	18.0 °C
1916	18.2 °C
1917	16.9 °C
1918	18.2 °C
1919	18.8 °C
1920	17.4 °C
1921	20.5 °C
1922	19.4 °C
1923	18.6 °C
1924	16.5 °C
1925	18.7 °C
1926	17.9 °C
1927	17.2 °C
1928	17.2 °C
1929	17.7 °C
1930	20.1 °C
1931	20.1 °C
1932	19.2 °C
1933	20.3 °C
1934	20.8 °C
1935	18.0 °C
1936	19.9 °C
1937	18.7 °C
1938	19.3 °C
1939	19.5 °C
1940	19.1 °C
1941	20.2 °C
1942	19.0 °C
1943	18.2 °C
1944	18.8 °C
1945	17.5 °C
1946	18.0 °C
1947	18.7 °C
1948	19.0 °C
1949	18.6 °C
1950	17.2 °C
1951	18.0 °C
1952	19.1 °C
1953	18.3 °C
1954	19.1 °C
1955	19.6 °C
1956	18.3 °C
1958	18.2 °C
1959	19.4 °C
1960	18.7 °C
1961	18.1 °C
1962	18.5 °C
1963	19.1 °C
1964	19.2 °C
1965	18.1 °C
1966	17.4 °C
1967	17.6 °C
1968	18.7 °C
1969	18.8 °C
1970	19.3 °C
1971	19.0 °C
1972	18.6 °C
1973	18.8 °C
1974	18.3 °C
1975	18.7 °C
1976	18.7 °C
1977	20.6 °C
1978	19.3 °C
1979	18.5 °C
1980	19.7 °C
1981	19.0 °C
1982	18.2 °C
1983	19.5 °C
1984	18.4 °C
1985	19.3 °C
1986	19.6 °C
1987	19.9 °C
1988	20.7 °C
1989	17.5 °C
1990	17.5 °C
1992	16.5 °C
1993	17.1 °C
1994	17.6 °C
1995	17.9 °C
1996	17.1 °C
1997	17.1 °C
1998	19.3 °C
1999	18.5 °C
2000	18.6 °C
2001	18.7 °C
2003	17.3 °C
2004	17.5 °C
2005	19.4 °C
2006	18.4 °C
2007	19.0 °C
2009	16.9 °C
2010	19.0 °C
2011	18.1 °C
2012	18.8 °C
2013	17.5 °C
2016	19.2 °C
2017	18.5 °C
2018	18.9 °C
2019	18.1 °C
2020	17.7 °C
2021	18.6 °C
2022	18.5 °C
2023	19.0 °C
2024	18.9 °C
2025	18.9 °C
2026	19.6 °C

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

Source: daily records from Williamsburg 1e (NOAA GHCN-Daily). Years with too many missing days are left out.

Nearby towns

Williamsburg Belle Plaine Walford Fairfax Atkins North English