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How to Protect Your Garden From Frost

Lynn has been a professional organic farmer for the last 35 years and runs a 210-acre farm in Western Colorado with her husband.

Save your plants so you can harvest at the end of the season.

Save your plants so you can harvest at the end of the season.

How to Cover Plants for Frost Protection

Your garden is really starting to come on and finally you have peppers, tomatoes and winter squash, but they're not quite ripe and you want to save the plants from the killing frost so you can harvest at the end of the season. This happens every year to us: The harvest is just not quite ready to pick, and then a cold front comes through and it freezes the garden. So we have perfected our frost protocol with three easy steps.

Here is the frost protocol that we use for our gardens.

Step 1: Monitor the Forecast and Check the Temperature

First we need to monitor the forecast. Check the weather forecast for your area from the same feed every day—in other words, whatever computer or phone or wherever you're getting your feed from, check the same one every day. Then, go out and check the actual temperature in your garden, and figure out the discrepancy from the forecast to the actual temperature in your garden.

For me, there is about a four degree difference in this. So if the forecast is predicted to go to 36 degrees Fahrenheit, then I know that my garden will be down around freezing because of this little discrepancy.

Step 2: Add Frost Covers at Night

You want to have your frost covers ready to go before you need them. Here's what I use for frost covers:

  • Layer 1: Wires
  • Layer 2: Blankets
  • Layer 3: Plastic
  • Layer 4: Wires

Layer 1: Wires

The first thing that I do is I put down some kind of structure to hold the blankets up off the plant. You want a little pillow of air between the plants and the blankets, because otherwise the cold air can come down through the cover if it's actually touching the plants. So, I get a wire or some kind of structure—it could be a cold frame.

Layer 2: Blankets

Next, I put on my blanket. The blankets that you use can be heavy frost blankets that you buy commercially, a quilt, a blanket off your bed, or towels. You can use any big blanket that will cover all the way around the edges.

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Layer 3: Plastic

On top of the blankets is a waterproof layer. If it's raining or snowing, you've got to keep your blankets dry, because otherwise they don't insulate well. So, you want to put your plastic on.

We use old greenhouse roofs because we just have a lot of that around whenever we change out the roofs. But you can go with a tarp. It doesn't have to be see-through to put on the plants at night.

Layer 4: Wires

Next, you'll also need a way to keep that plastic or waterproof layer on, because almost every single time a cold front comes in, you'll get a wind along with that. You're going to want hold the covers on so that they protect the plants. I put on another wire to hold it all together and keep the wind from getting to it.

I use a hardware mesh that you can get at the lumberyard (it's also used for cement—it gets laid in the cement). I put it right on top, and then I put string on it and tie the string to a block, a stake, a brick, anything—and that will secure. We've had these on through 50 mph winds, and everything inside was still protected and doing really well.

The plants go through the night like this. However, one of the things that we found out is that some cold air can get trapped underneath the cover. The next step will help with that.

Step 3: Uncover the Plants During the Day

The third step is to uncover your plants during the heat of the day. You take the wire off, and then you want to let in warm air. Let's say it's 32 at night and then it raises to 50 or 60 during the day. You want that 50 to 60 degree air underneath the cover.

What I like to do is just flip the covers back, even just halfway. That'll let that air exchange in there. If you have a dark tarp on top, you're going to want to get that flipped back off the plants so that the plants can get their light.

So, you want the warmer air to come in the middle of the day and you want the light. Then if it's cold again the next night, everything goes back down again.

Best of Luck With Your Garden!

So with a little vigilance and preparation, you can keep your peppers, tomatoes, and squash growing in your garden about four weeks after your first fall frost. And in that amount of time, you can really get a lot more produce from your garden. So it's well worth the effort, and if you are set up, it is really, really easy.

That's all for today. Until next time, may your garden be easy, fun, productive, and always organic.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2021 Lynn Gillespie

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