When to plant in Forsyth, MT
Planting dates worked out from Forsyth's own frost records, not a generic zone chart.
Safe to plant out
May 21
1 year in 10 has a later frost
Average last frost
May 11
about a 50% chance of a later one
Average first fall frost
Sep 26
1 year in 10 by Sep 14
Frost-free days
138
median, 1991–2020
Station used: Forsyth · 0.7 km away · station 767 m, town 768 m. How we match towns to stations
This season
Plan your garden.
Planting dates for common crops
| Crop | Start indoors | Plant out or sow | Harvest from |
|---|---|---|---|
| Tomato | Mar 26 – Apr 9 | May 21 – Jun 4 | Jul 15 |
| Sweet pepper | Mar 12 – Mar 26 | May 21 – Jun 4 | Jul 20 |
| Lettuce (leaf) | Mar 9 – Mar 16 | Apr 13 – Apr 27 | May 23 |
| Peas | — | Apr 3 – May 1 | May 28 |
| Bush beans | — | May 14 – Jun 4 | Jul 3 |
| Carrot | — | Apr 20 – Jun 1 | Jun 19 |
| Beet | — | Apr 16 – May 28 | Jun 5 |
| Potato | — | Apr 20 – May 11 | Jun 29 |
| Kale | Mar 2 – Mar 16 | Apr 13 – Apr 27 | May 26 |
| Broccoli | Mar 2 – Mar 16 | Apr 13 – May 4 | Jun 12 |
| Cucumber | Apr 23 – Apr 30 | May 21 – Jun 4 | Jul 10 |
| Summer squash and zucchini | Apr 23 – Apr 30 | May 21 – Jun 4 | Jul 5 |
| Winter squash | Apr 23 – Apr 30 | May 21 – Jun 4 | Aug 9 |
| Sweet corn | — | May 14 – Jun 4 | Jul 13 |
| Onion (from sets) | — | Apr 13 – May 4 | Jul 12 |
| Garlic | — | Sep 12 – Oct 10 (fall) | following summer |
| Spinach | — | Apr 3 – May 1 | May 11 |
| Basil | Apr 9 – Apr 23 | May 21 – Jun 4 | Jul 17 |
Forsyth'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 |
|---|---|
| 1976 | May 3 |
| 1977 | May 5 |
| 1978 | May 9 |
| 1979 | May 20 |
| 1980 | May 14 |
| 1981 | May 9 |
| 1982 | May 30 |
| 1983 | May 15 |
| 1984 | May 9 |
| 1985 | May 15 |
| 1986 | May 17 |
| 1987 | Apr 22 |
| 1988 | May 3 |
| 1989 | May 2 |
| 1990 | May 17 |
| 1991 | May 5 |
| 1992 | May 21 |
| 1993 | Apr 25 |
| 1994 | Apr 30 |
| 1995 | May 14 |
| 1996 | May 11 |
| 1997 | May 19 |
| 1998 | May 10 |
| 1999 | May 18 |
| 2000 | May 14 |
| 2001 | May 3 |
| 2002 | May 24 |
| 2003 | May 21 |
| 2004 | May 26 |
| 2005 | May 14 |
| 2006 | May 6 |
| 2007 | May 24 |
| 2008 | May 12 |
| 2009 | May 13 |
| 2010 | May 8 |
| 2011 | May 5 |
| 2012 | May 12 |
| 2013 | May 11 |
| 2014 | May 1 |
| 2015 | May 20 |
| 2016 | May 14 |
| 2017 | Apr 26 |
| 2018 | Apr 25 |
| 2019 | May 18 |
| 2020 | May 11 |
| 2021 | May 11 |
| 2022 | May 22 |
| 2023 | Apr 30 |
| 2024 | May 4 |
| 2025 | May 2 |
| 2026 | May 19 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1976 | 128 |
| 1977 | 141 |
| 1978 | 132 |
| 1979 | 116 |
| 1980 | 133 |
| 1981 | 130 |
| 1982 | 112 |
| 1983 | 145 |
| 1984 | 136 |
| 1985 | 130 |
| 1986 | 146 |
| 1987 | 166 |
| 1988 | 154 |
| 1989 | 131 |
| 1990 | 128 |
| 1991 | 135 |
| 1992 | 95 |
| 1993 | 141 |
| 1994 | 160 |
| 1995 | 129 |
| 1996 | 138 |
| 1997 | 123 |
| 1998 | 148 |
| 1999 | 133 |
| 2000 | 130 |
| 2001 | 154 |
| 2002 | 120 |
| 2003 | 119 |
| 2004 | 127 |
| 2005 | 142 |
| 2006 | 144 |
| 2007 | 112 |
| 2008 | 139 |
| 2009 | 131 |
| 2010 | 157 |
| 2011 | 138 |
| 2012 | 144 |
| 2013 | 145 |
| 2014 | 132 |
| 2015 | 147 |
| 2016 | 144 |
| 2017 | 159 |
| 2018 | 160 |
| 2019 | 135 |
| 2020 | 120 |
| 2021 | 153 |
| 2022 | 146 |
| 2023 | 158 |
| 2024 | 149 |
| 2025 | 162 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1976 | 17.7 °C |
| 1977 | 17.6 °C |
| 1978 | 16.5 °C |
| 1979 | 16.4 °C |
| 1980 | 17.4 °C |
| 1981 | 16.8 °C |
| 1982 | 15.8 °C |
| 1983 | 16.9 °C |
| 1984 | 16.4 °C |
| 1985 | 16.2 °C |
| 1986 | 16.1 °C |
| 1987 | 17.4 °C |
| 1988 | 19.0 °C |
| 1989 | 16.6 °C |
| 1990 | 17.3 °C |
| 1991 | 17.1 °C |
| 1992 | 15.8 °C |
| 1993 | 15.2 °C |
| 1994 | 18.0 °C |
| 1995 | 16.3 °C |
| 1996 | 16.8 °C |
| 1997 | 17.1 °C |
| 1998 | 18.4 °C |
| 1999 | 16.4 °C |
| 2001 | 18.4 °C |
| 2002 | 17.0 °C |
| 2003 | 17.8 °C |
| 2004 | 16.2 °C |
| 2005 | 17.1 °C |
| 2006 | 18.1 °C |
| 2007 | 17.9 °C |
| 2008 | 15.6 °C |
| 2009 | 16.1 °C |
| 2010 | 16.0 °C |
| 2011 | 16.2 °C |
| 2012 | 18.1 °C |
| 2013 | 17.2 °C |
| 2014 | 16.3 °C |
| 2015 | 17.3 °C |
| 2016 | 17.5 °C |
| 2017 | 17.6 °C |
| 2018 | 16.6 °C |
| 2019 | 16.0 °C |
| 2020 | 16.7 °C |
| 2021 | 17.7 °C |
| 2022 | 17.1 °C |
| 2023 | 17.9 °C |
| 2024 | 17.5 °C |
| 2025 | 17.6 °C |
| 2026 | 17.7 °C |
What this means for you: Since 1976, Forsyth's last spring frost has stayed at about the same time of year. The frost-free season has grown by about 4 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Forsyth (NOAA GHCN-Daily). Years with too many missing days are left out.