When to plant in Windsor, CO
Planting dates worked out from Windsor's own frost records, not a generic zone chart.
Safe to plant out
May 14
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 3
1 year in 10 by Sep 13
Frost-free days
149
median, 1991–2020
Station used: Ft Collins 4 E · 15.0 km away · station 1500 m, town 1462 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 19 – Apr 2 | May 14 – May 28 | Jul 8 |
| Sweet pepper | Mar 5 – Mar 19 | May 14 – May 28 | Jul 13 |
| Lettuce (leaf) | Mar 3 – Mar 10 | Apr 7 – Apr 21 | May 17 |
| Peas | — | Mar 24 – Apr 21 | May 18 |
| Bush beans | — | May 7 – May 28 | Jun 26 |
| Carrot | — | Apr 14 – May 26 | Jun 13 |
| Beet | — | Apr 11 – May 23 | May 31 |
| 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 16 – Apr 23 | May 14 – May 28 | Jul 3 |
| Summer squash and zucchini | Apr 16 – Apr 23 | May 14 – May 28 | Jun 28 |
| Winter squash | Apr 16 – Apr 23 | May 14 – May 28 | Aug 2 |
| Sweet corn | — | May 7 – May 28 | Jul 6 |
| Onion (from sets) | — | Apr 7 – Apr 28 | Jul 6 |
| Garlic | — | Sep 19 – Oct 17 (fall) | following summer |
| Spinach | — | Mar 24 – Apr 21 | May 1 |
| Basil | Apr 2 – Apr 16 | May 14 – May 28 | Jul 10 |
Windsor'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 |
|---|---|
| 1991 | May 3 |
| 1992 | Apr 26 |
| 1993 | May 2 |
| 1994 | Apr 30 |
| 1995 | May 4 |
| 1996 | Apr 29 |
| 1997 | May 12 |
| 1998 | Apr 29 |
| 1999 | May 12 |
| 2000 | May 13 |
| 2001 | May 3 |
| 2002 | May 24 |
| 2003 | May 11 |
| 2004 | May 2 |
| 2005 | May 12 |
| 2006 | May 11 |
| 2007 | Apr 15 |
| 2008 | May 14 |
| 2009 | Apr 27 |
| 2010 | May 13 |
| 2011 | May 5 |
| 2012 | Apr 17 |
| 2013 | May 3 |
| 2014 | May 14 |
| 2015 | May 11 |
| 2016 | May 2 |
| 2017 | May 18 |
| 2018 | Apr 27 |
| 2019 | May 11 |
| 2020 | Apr 19 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1991 | 143 |
| 1992 | 163 |
| 1993 | 133 |
| 1994 | 143 |
| 1995 | 138 |
| 1996 | 149 |
| 1997 | 149 |
| 1998 | 159 |
| 1999 | 138 |
| 2000 | 131 |
| 2001 | 128 |
| 2002 | 140 |
| 2003 | 142 |
| 2004 | 173 |
| 2005 | 147 |
| 2006 | 154 |
| 2007 | 175 |
| 2008 | 151 |
| 2009 | 157 |
| 2010 | 158 |
| 2011 | 165 |
| 2012 | 170 |
| 2013 | 155 |
| 2014 | 121 |
| 2015 | 165 |
| 2016 | 155 |
| 2017 | 137 |
| 2018 | 165 |
| 2019 | 148 |
| 2020 | 141 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1991 | 16.4 °C |
| 1992 | 16.3 °C |
| 1993 | 15.6 °C |
| 1994 | 17.2 °C |
| 1995 | 15.2 °C |
| 1996 | 16.5 °C |
| 1997 | 16.1 °C |
| 1998 | 17.0 °C |
| 1999 | 15.8 °C |
| 2000 | 18.0 °C |
| 2001 | 17.9 °C |
| 2002 | 17.7 °C |
| 2003 | 17.3 °C |
| 2004 | 16.4 °C |
| 2005 | 17.1 °C |
| 2006 | 18.1 °C |
| 2007 | 17.8 °C |
| 2008 | 16.4 °C |
| 2009 | 16.2 °C |
| 2010 | 17.1 °C |
| 2011 | 17.1 °C |
| 2012 | 19.0 °C |
| 2013 | 17.1 °C |
| 2014 | 16.9 °C |
| 2015 | 17.4 °C |
| 2016 | 17.4 °C |
| 2017 | 17.2 °C |
| 2018 | 17.9 °C |
| 2019 | 17.1 °C |
| 2020 | 17.4 °C |
What this means for you: Since 1991, Windsor's last spring frost has stayed at about the same time of year. 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 Ft Collins 4 E (NOAA GHCN-Daily). Years with too many missing days are left out.