CO-Horts Blog

Thursday, September 8, 2022

You may not believe it, but cold IS coming

Posted by Todd Hagenbuch, Routt County CSU Extension

This week’s record temps may have us all lulled into a false sense that summer is here to stay, but if you’ve lived in Colorado for any length of time, you know that a frost is just around the corner…at any time! In the high mountain valleys of Northwest Colorado, we’ve typically had a scare with frost by now and are ready to get our gardens through a cool night. I think this Saturday might be my zucchini's closest brush with death this season with a projected low of 37 in Phippsburg…which usually translates to 5 degrees cooler at my house. So what will we do to get through the night in order to keep things going for another week or two?

Plants are all snug under sheets and tarps, plus old-
fashioned holiday lights provide extra heat.
Simple cloth covers like old bed sheets or floating row covers go a long way towards protecting sensitive plants when the temps are just at or near freezing. On Saturday, we’ll likely cover the summer squash, beans, and potatoes with old sheets that we have procured over the years from the local Phippsburg Community Club Rummage Shop. This simple layer of protection will be all those plants need when temps get down to even 30 degrees, and hardier plants like the cabbage and peas will be fine and cruise through the night without issue.

If it looks like it’s going to get even colder, then more extreme measures need to be taken. We have metal hoops to put over our plants so heavier materials don’t need to lay on top of them. We can spread the sheets or blankets over the hoops and trap the heat coming off of the soil to ensure plants remain in temps well-above freezing.

When one of those really cold snaps hits and we know we’re going to have another stretch of warm temps ahead, we go all-out to ensure we get our plants through the worst in order to get another week or two of growth out of them. Using the hoops with sheets and blankets to hold heat, we also cover the top with plastic so if it’s a wet storm that’s bringing the cold, the water is shed and doesn’t further weigh down the insulative layer.

If the soil isn’t warm enough to provide the warmth needed, we go a step further and pull out the old C-7 and C-9 holiday lights and string throughout the garden to increase the temps a few more degrees under the covers. Those old lights are super inefficient for holiday lighting when compared to the newer LED types, but that inefficiency means they are awesome heat producers. Take a look at the temperature difference between the space under the covers with the lights and outside- what a difference!

WOW- a 20 degree difference under the covers!
If you think a cold night is coming but that several growing days still exist in your plant’s future, take a little time to cover your garden so they can keep producing. Heck, I know your neighbor needs another zucchini even if they tell you they don’t!

For more information on how to protect your plants during a cold-snap, visit the CMG Garden Notes on the subject at

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