When to plant in Castle Pines, CO
Planting dates worked out from Castle Pines's own frost records, not a generic zone chart.
Safe to plant out
May 25
1 year in 10 has a later frost
Average last frost
May 12
about a 50% chance of a later one
Average first fall frost
Sep 30
1 year in 10 by Sep 13
Frost-free days
138
median, 1991–2020
Station used: Castle Rock · 8.4 km away · station 1876 m, town 1999 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 30 – Apr 13 | May 25 – Jun 8 | Jul 19 |
| Sweet pepper | Mar 16 – Mar 30 | May 25 – Jun 8 | Jul 24 |
| Lettuce (leaf) | Mar 10 – Mar 17 | Apr 14 – Apr 28 | May 24 |
| Peas | — | Mar 31 – Apr 28 | May 25 |
| Bush beans | — | May 18 – Jun 8 | Jul 7 |
| Carrot | — | Apr 21 – Jun 2 | Jun 20 |
| Beet | — | Apr 19 – May 31 | Jun 8 |
| Potato | — | Apr 21 – May 12 | Jun 30 |
| Kale | Mar 3 – Mar 17 | Apr 14 – Apr 28 | May 27 |
| Broccoli | Mar 3 – Mar 17 | Apr 14 – May 5 | Jun 13 |
| Cucumber | Apr 27 – May 4 | May 25 – Jun 8 | Jul 14 |
| Summer squash and zucchini | Apr 27 – May 4 | May 25 – Jun 8 | Jul 9 |
| Winter squash | Apr 27 – May 4 | May 25 – Jun 8 | Aug 13 |
| Sweet corn | — | May 18 – Jun 8 | Jul 17 |
| Onion (from sets) | — | Apr 14 – May 5 | Jul 13 |
| Garlic | — | Sep 16 – Oct 14 (fall) | following summer |
| Spinach | — | Mar 31 – Apr 28 | May 8 |
| Basil | Apr 13 – Apr 27 | May 25 – Jun 8 | Jul 21 |
Castle Pines'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 |
|---|---|
| 1893 | Jun 5 |
| 1894 | May 22 |
| 1896 | May 15 |
| 1898 | May 20 |
| 1899 | May 6 |
| 1900 | May 16 |
| 1901 | May 10 |
| 1902 | May 20 |
| 1903 | Jul 4 |
| 1904 | May 17 |
| 1906 | Jun 8 |
| 1907 | Jun 1 |
| 1908 | May 29 |
| 1909 | May 25 |
| 1911 | May 22 |
| 1912 | Jun 17 |
| 1914 | May 12 |
| 1915 | Jun 7 |
| 1916 | Jun 8 |
| 1917 | Jun 13 |
| 1921 | May 11 |
| 1922 | May 16 |
| 1923 | May 16 |
| 1924 | Jun 2 |
| 1927 | May 30 |
| 1928 | May 6 |
| 1929 | May 30 |
| 1963 | May 21 |
| 1964 | May 30 |
| 1965 | May 28 |
| 1966 | May 20 |
| 1967 | May 27 |
| 1968 | May 19 |
| 1969 | May 9 |
| 1970 | May 15 |
| 1971 | May 23 |
| 1972 | May 24 |
| 1973 | Jun 19 |
| 1974 | Jun 9 |
| 1975 | Jun 11 |
| 1976 | Jun 15 |
| 1977 | May 22 |
| 1979 | Jun 10 |
| 1981 | May 14 |
| 1982 | Jun 7 |
| 1983 | Jun 14 |
| 1984 | May 8 |
| 1986 | May 22 |
| 1987 | Apr 21 |
| 1988 | May 22 |
| 1989 | May 26 |
| 1991 | May 5 |
| 1992 | Apr 25 |
| 1993 | May 11 |
| 1994 | May 4 |
| 1995 | May 18 |
| 1996 | May 27 |
| 1997 | May 27 |
| 1998 | Jun 8 |
| 2000 | May 14 |
| 2001 | May 22 |
| 2002 | May 23 |
| 2003 | May 12 |
| 2004 | May 14 |
| 2005 | May 13 |
| 2006 | May 11 |
| 2007 | May 8 |
| 2008 | May 14 |
| 2009 | Apr 27 |
| 2010 | May 16 |
| 2011 | May 20 |
| 2012 | Apr 30 |
| 2015 | May 11 |
| 2016 | May 3 |
| 2017 | May 20 |
| 2020 | Apr 15 |
| 2021 | Apr 22 |
| 2023 | Apr 29 |
| 2024 | Apr 28 |
| 2025 | May 20 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1893 | 108 |
| 1896 | 132 |
| 1898 | 111 |
| 1899 | 133 |
| 1900 | 126 |
| 1901 | 129 |
| 1902 | 114 |
| 1903 | 71 |
| 1906 | 101 |
| 1907 | 100 |
| 1908 | 119 |
| 1912 | 87 |
| 1914 | 124 |
| 1915 | 98 |
| 1916 | 95 |
| 1917 | 105 |
| 1921 | 132 |
| 1922 | 143 |
| 1923 | 131 |
| 1924 | 121 |
| 1927 | 112 |
| 1928 | 137 |
| 1963 | 145 |
| 1964 | 119 |
| 1965 | 110 |
| 1966 | 132 |
| 1967 | 109 |
| 1968 | 119 |
| 1969 | 146 |
| 1970 | 129 |
| 1971 | 114 |
| 1972 | 128 |
| 1973 | 75 |
| 1974 | 94 |
| 1975 | 99 |
| 1977 | 140 |
| 1979 | 96 |
| 1981 | 144 |
| 1983 | 97 |
| 1984 | 137 |
| 1987 | 170 |
| 1988 | 118 |
| 1992 | 153 |
| 1993 | 124 |
| 1994 | 140 |
| 1995 | 125 |
| 1996 | 114 |
| 1997 | 137 |
| 1998 | 118 |
| 2000 | 131 |
| 2002 | 133 |
| 2003 | 124 |
| 2004 | 131 |
| 2005 | 144 |
| 2006 | 128 |
| 2007 | 152 |
| 2008 | 145 |
| 2010 | 155 |
| 2011 | 140 |
| 2012 | 156 |
| 2015 | 169 |
| 2016 | 156 |
| 2017 | 131 |
| 2020 | 183 |
| 2021 | 180 |
| 2023 | 167 |
| 2024 | 185 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1893 | 15.5 °C |
| 1894 | 15.9 °C |
| 1896 | 14.9 °C |
| 1897 | 16.4 °C |
| 1898 | 15.6 °C |
| 1899 | 15.6 °C |
| 1900 | 14.8 °C |
| 1901 | 15.8 °C |
| 1902 | 16.4 °C |
| 1903 | 14.7 °C |
| 1904 | 14.6 °C |
| 1906 | 15.3 °C |
| 1907 | 12.4 °C |
| 1908 | 14.3 °C |
| 1909 | 13.5 °C |
| 1911 | 15.9 °C |
| 1912 | 13.3 °C |
| 1914 | 14.8 °C |
| 1915 | 13.6 °C |
| 1916 | 14.5 °C |
| 1917 | 13.5 °C |
| 1921 | 15.2 °C |
| 1922 | 15.6 °C |
| 1923 | 14.8 °C |
| 1924 | 16.0 °C |
| 1926 | 13.4 °C |
| 1927 | 14.5 °C |
| 1928 | 14.2 °C |
| 1962 | 16.4 °C |
| 1963 | 16.8 °C |
| 1964 | 15.4 °C |
| 1965 | 14.6 °C |
| 1966 | 15.9 °C |
| 1967 | 15.0 °C |
| 1968 | 14.9 °C |
| 1969 | 16.5 °C |
| 1970 | 15.4 °C |
| 1971 | 14.5 °C |
| 1972 | 15.0 °C |
| 1973 | 14.1 °C |
| 1974 | 14.8 °C |
| 1975 | 14.6 °C |
| 1977 | 16.8 °C |
| 1979 | 15.7 °C |
| 1981 | 16.8 °C |
| 1982 | 15.5 °C |
| 1983 | 15.9 °C |
| 1984 | 15.3 °C |
| 1986 | 15.7 °C |
| 1987 | 15.6 °C |
| 1988 | 15.7 °C |
| 1989 | 15.2 °C |
| 1992 | 15.4 °C |
| 1993 | 14.7 °C |
| 1994 | 16.6 °C |
| 1995 | 14.4 °C |
| 1996 | 15.9 °C |
| 1997 | 15.1 °C |
| 1998 | 15.7 °C |
| 2000 | 16.6 °C |
| 2002 | 16.7 °C |
| 2003 | 16.0 °C |
| 2004 | 14.8 °C |
| 2005 | 15.9 °C |
| 2006 | 16.8 °C |
| 2007 | 16.6 °C |
| 2008 | 15.7 °C |
| 2010 | 16.6 °C |
| 2011 | 16.6 °C |
| 2012 | 17.9 °C |
| 2015 | 16.4 °C |
| 2016 | 16.6 °C |
| 2017 | 16.2 °C |
| 2019 | 17.6 °C |
| 2021 | 19.9 °C |
| 2023 | 16.2 °C |
| 2024 | 17.4 °C |
| 2025 | 17.1 °C |
What this means for you: Since 1893, Castle Pines's last spring frost has come about 1 day earlier per decade, on average. The frost-free season has grown by about 3 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Castle Rock (NOAA GHCN-Daily). Years with too many missing days are left out.