When to plant in Three Forks, MT

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

Safe to plant out

May 27

1 year in 10 has a later frost

Average last frost

May 16

about a 50% chance of a later one

Average first fall frost

Sep 21

1 year in 10 by Sep 8

Frost-free days

123

median, 1991–2020

Station used: Trident · 8.4 km away · station 1230 m, town 1242 m. How we match towns to stations

This season

Plan your garden.

Build my Three Forks plan

Planting dates for common crops

Crop	Start indoors	Plant out or sow	Harvest from
Tomato	Apr 1 – Apr 15	May 27 – Jun 10	Jul 21
Sweet pepper	Mar 18 – Apr 1	May 27 – Jun 10	Jul 26
Lettuce (leaf)	Mar 14 – Mar 21	Apr 18 – May 2	May 28
Peas	—	Apr 8 – May 6	Jun 2
Bush beans	—	May 20 – Jun 10	Jul 9
Carrot	—	Apr 25 – Jun 6	Jun 24
Beet	—	Apr 22 – Jun 3	Jun 11
Potato	—	Apr 25 – May 16	Jul 4
Kale	Mar 7 – Mar 21	Apr 18 – May 2	May 31
Broccoli	Mar 7 – Mar 21	Apr 18 – May 9	Jun 17
Cucumber	Apr 29 – May 6	May 27 – Jun 10	Jul 16
Summer squash and zucchini	Apr 29 – May 6	May 27 – Jun 10	Jul 11
Winter squash	Apr 29 – May 6	May 27 – Jun 10	Aug 15
Sweet corn	—	May 20 – Jun 10	Jul 19
Onion (from sets)	—	Apr 18 – May 9	Jul 17
Garlic	—	Sep 7 – Oct 5 (fall)	following summer
Spinach	—	Apr 8 – May 6	May 16
Basil	Apr 15 – Apr 29	May 27 – Jun 10	Jul 23

Plan all 65 crops for Three Forks

Three Forks'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
1924	Jun 7
1925	May 10
1926	May 9
1927	May 10
1928	May 4
1929	May 15
1930	May 11
1931	May 21
1932	Apr 10
1933	May 12
1934	May 13
1936	Apr 27
1937	Apr 25
1938	May 21
1939	Jun 2
1940	May 8
1941	May 20
1942	May 18
1943	Jun 6
1944	May 23
1945	Jun 14
1946	May 20
1947	May 29
1948	May 9
1949	May 7
1950	Jun 8
1951	Jun 3
1952	May 15
1953	May 15
1954	May 29
1955	May 28
1956	May 13
1957	Apr 27
1958	Apr 30
1959	May 23
1960	May 18
1961	May 14
1962	Jun 7
1963	May 2
1964	May 8
1965	May 18
1966	May 18
1967	May 26
1968	May 11
1969	May 8
1970	May 14
1971	May 23
1972	May 3
1973	May 27
1974	May 16
1975	May 26
1976	May 1
1977	May 30
1978	May 30
1979	Jun 9
1980	Apr 17
1981	Jul 8
1982	May 31
1983	May 15
1984	Jun 2
1985	May 16
1986	May 23
1987	May 3
1988	May 15
1989	May 30
1990	May 25
1991	Jun 16
1992	May 5
1993	May 9
1994	Apr 30
1995	May 23
1996	May 10
1997	May 19
1998	May 19
2002	May 23
2003	May 20
2005	May 12
2006	May 10
2011	May 11
2012	May 27
2013	May 5
2014	May 13
2015	May 11
2016	May 11
2017	May 19
2018	Jun 12
2019	May 10
2020	May 8
2021	May 22
2022	May 23

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1924	94
1925	132
1926	132
1927	127
1928	138
1929	111
1930	112
1931	124
1932	163
1933	133
1934	129
1936	141
1937	152
1938	135
1939	96
1940	150
1941	118
1942	130
1943	93
1944	117
1945	87
1946	124
1947	110
1948	143
1949	126
1950	96
1951	100
1952	121
1953	132
1954	112
1955	115
1956	140
1957	138
1958	152
1959	108
1960	113
1961	121
1962	93
1963	166
1964	125
1965	103
1966	134
1967	130
1968	145
1969	118
1970	119
1971	117
1972	143
1973	109
1974	108
1975	115
1976	129
1977	124
1978	106
1979	94
1980	157
1981	73
1982	106
1983	126
1984	102
1985	116
1986	122
1987	136
1988	126
1989	103
1990	130
1991	93
1992	109
1993	127
1994	144
1995	120
1996	118
1997	123
2002	121
2003	117
2005	137
2011	131
2012	129
2013	144
2014	121
2015	146
2016	148
2018	100
2019	140
2020	122
2021	117
2022	137

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

See the data as a table

Year	Growing-season temperature
1924	15.4 °C
1925	15.9 °C
1926	15.4 °C
1927	15.1 °C
1928	15.0 °C
1929	16.2 °C
1930	18.1 °C
1931	17.2 °C
1932	17.6 °C
1933	17.2 °C
1934	17.8 °C
1936	16.9 °C
1937	16.4 °C
1938	15.4 °C
1939	15.7 °C
1940	16.6 °C
1941	15.2 °C
1942	14.8 °C
1943	14.9 °C
1944	14.8 °C
1945	14.1 °C
1946	15.1 °C
1947	14.9 °C
1948	15.4 °C
1949	15.9 °C
1950	14.3 °C
1951	14.2 °C
1952	16.0 °C
1953	15.2 °C
1954	15.4 °C
1955	14.8 °C
1956	15.7 °C
1957	15.6 °C
1958	15.9 °C
1959	14.7 °C
1960	15.4 °C
1961	15.8 °C
1962	15.2 °C
1963	15.8 °C
1964	14.8 °C
1965	13.7 °C
1966	16.0 °C
1967	15.0 °C
1968	14.3 °C
1969	15.6 °C
1970	14.4 °C
1971	14.7 °C
1972	14.9 °C
1973	15.2 °C
1974	14.9 °C
1975	13.9 °C
1976	15.1 °C
1977	15.2 °C
1978	14.6 °C
1980	15.4 °C
1981	15.4 °C
1982	14.4 °C
1983	14.8 °C
1984	15.0 °C
1985	15.7 °C
1986	15.6 °C
1987	16.4 °C
1988	17.2 °C
1989	16.0 °C
1990	15.9 °C
1991	15.8 °C
1992	14.9 °C
1993	13.0 °C
1994	15.5 °C
1995	13.9 °C
1996	14.6 °C
1997	14.9 °C
1998	15.6 °C
2002	14.8 °C
2005	15.1 °C
2011	14.2 °C
2012	15.6 °C
2013	15.6 °C
2014	14.6 °C
2015	15.3 °C
2016	14.8 °C
2017	15.1 °C
2018	14.6 °C
2019	14.8 °C
2020	15.1 °C
2021	15.9 °C
2022	15.2 °C
2023	16.0 °C

What this means for you: Since 1924, Three Forks'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 Trident (NOAA GHCN-Daily). Years with too many missing days are left out.

Nearby towns

Manhattan Belgrade Four Corners Whitehall Bozeman Townsend