When to plant in Broomfield, CO
Planting dates worked out from Broomfield's own frost records, not a generic zone chart.
Safe to plant out
May 17
1 year in 10 has a later frost
Average last frost
May 5
about a 50% chance of a later one
Average first fall frost
Oct 8
1 year in 10 by Sep 21
Frost-free days
153
median, 1991–2020
Station used: Northglenn · 6.7 km away · station 1637 m, town 1644 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 22 – Apr 5 | May 17 – May 31 | Jul 11 |
| Sweet pepper | Mar 8 – Mar 22 | May 17 – May 31 | Jul 16 |
| Lettuce (leaf) | Mar 3 – Mar 10 | Apr 7 – Apr 21 | May 17 |
| Peas | — | Mar 24 – Apr 21 | May 18 |
| Bush beans | — | May 10 – May 31 | Jun 29 |
| Carrot | — | Apr 14 – May 26 | Jun 13 |
| Beet | — | Apr 7 – May 19 | May 27 |
| Potato | — | Apr 14 – May 5 | Jun 23 |
| Kale | Feb 24 – Mar 10 | Apr 7 – Apr 21 | May 20 |
| Broccoli | Feb 24 – Mar 10 | Apr 7 – Apr 28 | Jun 6 |
| Cucumber | Apr 19 – Apr 26 | May 17 – May 31 | Jul 6 |
| Summer squash and zucchini | Apr 19 – Apr 26 | May 17 – May 31 | Jul 1 |
| Winter squash | Apr 19 – Apr 26 | May 17 – May 31 | Aug 5 |
| Sweet corn | — | May 10 – May 31 | Jul 9 |
| Onion (from sets) | — | Apr 7 – Apr 28 | Jul 6 |
| Garlic | — | Sep 24 – Oct 22 (fall) | following summer |
| Spinach | — | Mar 24 – Apr 21 | May 1 |
| Basil | Apr 5 – Apr 19 | May 17 – May 31 | Jul 13 |
Broomfield'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 |
|---|---|
| 1985 | Apr 27 |
| 1986 | May 23 |
| 1987 | May 3 |
| 1990 | May 10 |
| 1991 | May 3 |
| 1992 | Apr 25 |
| 1993 | May 10 |
| 1994 | Apr 30 |
| 1995 | May 14 |
| 1996 | Apr 30 |
| 1997 | May 3 |
| 1998 | Apr 29 |
| 2000 | May 13 |
| 2001 | May 21 |
| 2002 | May 24 |
| 2003 | May 16 |
| 2004 | May 1 |
| 2005 | May 12 |
| 2006 | May 11 |
| 2007 | Apr 15 |
| 2008 | May 11 |
| 2009 | Apr 19 |
| 2010 | May 13 |
| 2011 | May 6 |
| 2012 | Apr 16 |
| 2013 | May 3 |
| 2014 | May 13 |
| 2015 | May 11 |
| 2016 | May 2 |
| 2017 | May 20 |
| 2018 | Apr 25 |
| 2019 | May 1 |
| 2020 | Apr 18 |
| 2022 | May 22 |
| 2023 | Apr 24 |
| 2024 | Apr 22 |
| 2025 | Apr 20 |
| 2026 | May 7 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1985 | 148 |
| 1987 | 132 |
| 1990 | 149 |
| 1991 | 153 |
| 1992 | 164 |
| 1993 | 125 |
| 1994 | 143 |
| 1995 | 129 |
| 1996 | 147 |
| 1997 | 161 |
| 1998 | 153 |
| 2000 | 131 |
| 2001 | 136 |
| 2002 | 140 |
| 2003 | 161 |
| 2004 | 176 |
| 2005 | 147 |
| 2006 | 134 |
| 2007 | 183 |
| 2008 | 154 |
| 2010 | 167 |
| 2011 | 165 |
| 2013 | 153 |
| 2014 | 122 |
| 2015 | 178 |
| 2016 | 193 |
| 2017 | 142 |
| 2018 | 172 |
| 2019 | 159 |
| 2020 | 165 |
| 2022 | 147 |
| 2023 | 171 |
| 2024 | 185 |
| 2025 | 181 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1985 | 16.8 °C |
| 1986 | 16.2 °C |
| 1987 | 16.4 °C |
| 1988 | 17.0 °C |
| 1990 | 17.8 °C |
| 1991 | 17.1 °C |
| 1992 | 17.3 °C |
| 1993 | 16.4 °C |
| 1994 | 18.3 °C |
| 1995 | 14.5 °C |
| 1996 | 16.2 °C |
| 1997 | 17.3 °C |
| 1998 | 18.2 °C |
| 2000 | 19.2 °C |
| 2001 | 19.1 °C |
| 2002 | 19.4 °C |
| 2003 | 18.9 °C |
| 2004 | 17.8 °C |
| 2005 | 18.5 °C |
| 2006 | 19.3 °C |
| 2007 | 18.9 °C |
| 2008 | 18.8 °C |
| 2009 | 17.7 °C |
| 2010 | 18.2 °C |
| 2011 | 18.1 °C |
| 2013 | 17.9 °C |
| 2014 | 17.9 °C |
| 2015 | 18.0 °C |
| 2016 | 18.5 °C |
| 2017 | 18.3 °C |
| 2018 | 19.6 °C |
| 2019 | 19.0 °C |
| 2020 | 19.7 °C |
| 2022 | 19.4 °C |
| 2023 | 18.2 °C |
| 2024 | 19.4 °C |
| 2025 | 19.1 °C |
| 2026 | 20.3 °C |
What this means for you: Since 1985, Broomfield's last spring frost has come about 2 days earlier per decade, on average. The frost-free season has grown by about 8 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Northglenn (NOAA GHCN-Daily). Years with too many missing days are left out.