It was cold this morning, zero according to the thermometer. In most places there have been frosts already, but we haven’t really had any until now.

Our farm is backed up against a rock face that collects and holds the sun’s heat – a definite plus for gardening up here. My tomato plants weren’t covered, either, so they were the first thing I checked when I saw the frost.

They didn’t seem to be touched at all. But as soon as the sun comes around the mountain, we will see for sure if they were. Frost damage doesn’t always show until the sun hits the plants.

Frost damage isn’t actually caused by the freezing of moisture on the plant, but by the ice crystals penetrating it as the sun warms it. So, by covering plants, this protects them from damage. It also keeps any heat closer to the plant, just like a jacket does for us when it cools down.

There are ways we can avoid frost damage just by where we put certain plants. With tomatoes, I usually plant them in containers and try to keep them close to a building or structure that will hold heat.

If I do put them into the main garden, I put old tires around them. This not only holds heat, but it also acts as a mulch and will funnel rainwater toward the plant.

I also have a wall of old tires around the big garden. This helps to hold the heat and, hopefully, to channel the frost around and away from the plants inside the wall.

Sometimes the way to avoid frost damage is actually in the variety of vegetables that you plant. Some are hardier than others. The hardy plants generally have thicker leaves and stems. This helps prevent the leaves from being punctured by ice crystals.

Some vegetables are more hardy, having originated from areas that have frost. Vegetables of the cabbage family tend to handle frost without much problem. And root crops are usually OK as well. Potatoes, however, can’t take much frost.

One year we got a killing frost at the beginning of August. All of our potato plants were gone. But, being summer, we were too busy to harvest right then. I figured that the potatoes would be OK if we left them in the ground.

The most remarkable thing about it was that some of the red potato plants were trying to make a comeback when we did finally harvest. The frost had only stunted them and not killed them.

There is also a way to try and save a plant that is hit by frost. A couple of years ago, I went out to harvest lettuce (for our last market of the season), only to see that it was coated with frost crystals.

I had read somewhere that if you can water the plants before the sun gets to them, they will often survive the frost. So that is what I did. There I was, watering them frantically as the sun came over the horizon. I managed it, though, and that day I was able to sell those heads of lettuce.

The water melts the ice crystals so that they do no damage, which is what I did this morning with the tomatoes and most of them survived, too.