How to Properly Protect Your Outdoor Plants From Frost

Each year as the seasons change, there are a few times where the temperatures dip just near freezing, allowing dew to freeze and cover everything it's touched. It's beautiful to see—until you realized it probably killed all of your plants in one go.

Frost is unavoidable, but there are plenty of ways to ensure your precious garden isn't wiped out by a drop in the temperature. Whether you want to protect your flower bed, cover your veggie garden, or learn how to move your container plants to a safer location, we rounded up the best ways to ensure your plants survive a cold night (or many cold nights if need be).

At What Temperature Should You Be Concerned About Frost?

According to the Farmer's Almanac, you should expect frost when the nighttime temperature drops at or below 32 degrees Fahrenheit. If the temperature reaches just around 32 for a couple of hours, then the frost will likely be light, as it won't have time to form a heavy, icy layer over your plants. Most plants can survive a light frost, but not all will.

However, if the temperature dips to 28 degrees or lower for more than four consecutive hours, then that is considered a heavy frost. This will kill most warm-weather plants, unfortunately. If you're watching the evening weather or looking ahead for the week, prepare to cover your plants or bring them in if the weather looks like it will be cold enough for a light or heavy frost. It's always better to be safe than to be sorry.

Additionally, you can make an educated guess on whether or not it will frost based on your region's average frost dates. These dates are available in the Farmer's Almanac, but there's also a frost calculator tool online you can use.

The Best Ways to Shield Plants From a Frost

There are a myriad of ways to protect your plants from a frost, and it really depends on the types of plants you have in terms of how you shield them. You can cover, move, or pull up and store certain kinds of plants, while others may benefit from the occasional light frost (like broccoli and spinach).

• If you know that frost isn't going to stick around for long, covering your plants is a rather easy way to protect them from a light layer of ice. You can use things like an old sheet or light blanket to cover large areas, or you can lightly wrap potted plants in a sheet or other fabric to better protect them and hold them in heat. There are horticultural fleeces that you can buy for plants, too, if you prefer to have something specific to gardening. In a pinch, you can use something like bubble wrap to lightly cover plants, although you may want to secure it to the ground somehow to keep it from blowing away.
• For tender plants, you can also cover them with a glass or plastic dome or cloche. This creates a quick cover over seedlings or smaller sprouts, and it's easily removable once the sun comes out again.
• If you really want to protect your plants, you can create a cold frame—basically a mini greenhouse—out of wire and plastic sheeting. Simply bend sturdy wire over the plants, cover those arches with plastic sheeting, and secure the sheeting into the ground. This will keep frost out and heat in, while also increasing humidity.
• Another simple fix is adding mulch around plants. This will keep heat in the ground and act as a blanket of sorts, protecting roots from frigid temps even if the leaves are exposed.
• If you have a garden full of perennials, you could even pull them up and store them until things warm up again. This one is probably the most effort, but it works if you don't mind some pulling and replanting.
• For small items like potted plants, it's easy to bring them indoors for a night or two to avoid frost.

Tips to Prevent Your Plants from Freezing

While a frost is essentially a short freeze, a harsh freeze is more intense. In this case, try to cover your plants earlier in the day to trap warmer air under a cover (like a blanket, sheet, or plastic sheet). This will keep dew off the plants and hopefully keep them warmer while temperatures drop.

Items like baskets, jars, or plastic containers turned over a plant to completely cover it can also help prevent freezing. Of course, for smaller potted plants, bring them indoors for the night so they survive.