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When to plant in Gunbarrel, CO

Planting dates worked out from Gunbarrel'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 7
about a 50% chance of a later one
Average first fall frost
Oct 5
1 year in 10 by Sep 22
Frost-free days
154
median, 1991–2020

Station used: Boulder · 11.3 km away · station 1673 m, town 1610 m. How we match towns to stations

This season

Plan your garden.

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Planting dates for common crops

CropStart indoorsPlant out or sowHarvest 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 5 – Mar 12 Apr 9 – Apr 23 May 19
Peas — Mar 26 – Apr 23 May 20
Bush beans — May 14 – Jun 4 Jul 3
Carrot — Apr 16 – May 28 Jun 15
Beet — Apr 9 – May 21 May 29
Potato — Apr 16 – May 7 Jun 25
Kale Feb 26 – Mar 12 Apr 9 – Apr 23 May 22
Broccoli Feb 26 – Mar 12 Apr 9 – Apr 30 Jun 8
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 9 – Apr 30 Jul 8
Garlic — Sep 21 – Oct 19 (fall) following summer
Spinach — Mar 26 – Apr 23 May 3
Basil Apr 9 – Apr 23 May 21 – Jun 4 Jul 17

Plan all 65 crops for Gunbarrel

Gunbarrel's weather over time

How the growing season has shifted here, year by year, from the station's own records.

Apr 1May 1Jun 1Jul 1 1900191019201930194019501960197019801990200020102020
Each year's last spring frostLong-term trend
See the data as a table
YearLast spring frost
1895Apr 25
1898May 7
1899May 4
1900May 1
1901Apr 17
1902Apr 23
1903May 2
1904May 3
1905May 11
1906May 6
1907Jun 2
1908May 28
1909May 9
1910May 17
1911May 11
1913May 2
1914May 12
1915May 21
1916May 15
1917Jun 7
1918Apr 27
1919Jun 2
1920May 1
1921May 2
1922Apr 27
1923May 16
1924May 10
1925May 1
1926Apr 24
1927May 10
1928May 4
1929May 6
1930May 18
1931May 22
1932Apr 30
1933May 13
1934May 13
1935Jun 29
1936May 7
1937Apr 28
1938May 7
1939May 12
1940Apr 30
1941Apr 24
1942May 18
1943May 20
1944May 8
1945May 21
1946May 20
1947Jun 13
1948May 13
1949Apr 15
1950May 26
1951Jun 3
1952Apr 22
1953May 13
1954May 3
1955Apr 28
1956Apr 10
1957May 17
1958Apr 30
1959Apr 21
1960May 19
1961Apr 27
1962Apr 12
1963Apr 23
1964Apr 18
1965May 9
1966May 13
1967May 14
1968May 17
1969Apr 28
1970May 1
1971Apr 27
1972May 2
1973May 3
1974Apr 30
1975May 1
1976May 1
1977Apr 21
1978May 6
1980Apr 25
1981May 10
1982May 6
1983May 14
1984Apr 30
1985May 14
1986Apr 19
1987Apr 21
1988May 3
1989May 1
1991May 3
1992Apr 25
1993May 2
1994May 4
1995May 24
1996Apr 29
1997May 3
1998Apr 29
1999May 17
2000May 13
2001May 21
2002May 24
2003May 11
2004May 1
2005May 3
2006May 11
2007May 6
2008May 11
2010May 13
2011May 5
2012Apr 4
2013May 5
2014May 14
2015May 11
2016May 2
2017May 20
2018Apr 25
2019May 22
2020Apr 18
2021Apr 24
2022May 22
2023Apr 28
2024Apr 27
2025Apr 20
2026May 7

What this means for you: Since 1895, Gunbarrel'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 Boulder (NOAA GHCN-Daily). Years with too many missing days are left out.

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