Whether you’re trying to garden through the winter, like I am, or getting ready for springtime planting, being able to protect your plants from frost is a necessary skill to have.
Where I live, It’s getting chilly out at night, right when I finally have a bit of a garden going that seems to be doing well! Figures! So I was wondering what all of my options are to protect my plants from frost. And because you probably live somewhere that gets much colder in the winter than I do, I thought I would share my research with you all.
What is “frost” and how do you know when there will be “frost”?
Merriam Webster defines frost as “a covering of minute ice crystals on a cold surface” as well as “the temperature that causes freezing.” So with plants, we are concerned about the freezing of water, which has a freezing point of 32 degrees Fahrenheit. Therefore, when it is predicted that the temperature in your area will be 32 degrees or lower, you should protect your plants.
Why do you need to protect plants from frost?
According to Marin Master Gardeners, frost affects a plant by interrupting the flow of water due to the formation of ice crystals. This causes plant damage and can even kill your plants if enough damage is done. So protect all that hard work you’ve put into those plants by being sure to prepare for the frosts!
Do you need to protect all plants from frost?
Marin Master Gardeners reports that certain plants are more cold tolerant than other plants. Plants that are susceptible to the cold are known as “tender.” Tender plants include but are not limited to: citrus, avocados, bougainvillea, fuchsias, and succulents.
How do you protect plants from frost?
Choose Hardy Plants
Choosing plants that are less likely to be affected by frost is an easy way to deal with the possibility of frost. According to Jill Spencer at Dengarden, some good choices of hardy plants are crocuses, narcissus, tulips, grape hyacinths, and pansies; and for edibles, broccoli, cabbage, calendula, carrots, chives, lettuce, leeks, peas, radish, spinach, and Swiss chard are great options.
To find out if your plants are cold hardy, check out the 2012 USDA Hardiness Zone Map. To find plants ideally suited to your area, use the map to find out what zone you are in and match that up to the zone listed on the plants at the nursery. You can certainly grow plants from other zones, but the plant’s assigned zone will be a good clue as to how much care they will need and how much you will need to baby them in the winter.
Your local nursery is also a great resource for finding out what will work well in your area.
Site Selection
Site selection can be a very good defense against frost. Marin Master Gardeners sites that things like “elevation, surface reflectivity, soil properties, canopy cover, and proximity of structures or plants can all affect heat radiation within your landscape.”
So when you’re deciding where to place your tender plants, you’ll want to think about what they’re next to. Other plants, walls, fences, and large rocks can shield plants them and help create a warmer microclimate.
The Old Farmer’s Almanac also advises that you also want to be sure to think about the elevation, exposure, and slope of your plantings. You don’t want to put tender plants in dips in elevation where cold air might settle. A south-facing slope provides both exposure to the sun and better drainage of cold air, making it an ideal position for your garden if possible.
Water
For plants other than succulents, watering them thoroughly before a frost can be helpful because wet soil holds heat better than dry soil, which protects your plants’ roots. Succulents are actually more at risk for cells bursting due to frost if their cells are plump with water, so you’ll want to keep them on the dry side. (Marin Master Gardeners)
Coverings
When using coverings, you’ll want to have them in place by early evening and remove them the next day by mid morning. Make sure your coverings go all the way to the ground to capture the heat radiating from the ground, and don’t tie the cover onto the trunk, if it’s a tree. (Old Farmers Almanac, Dengarden)
Most garden centers sell plant covers, but you can also use things like bedsheets, drop cloths, blankets, towels, or plastic sheets, basically whatever you’ve got that will trap heat, to cover your plants and protect them from frost.
The Old Farmer’s Almanac spoke of an interesting idea to use clear plastic drink bottles cut in half as covers for your plants, screwing the lid on when frost is forecasted and leaving it open when the weather is good. This is known as a cloche.
Around here, you’ll see people put Styrofoam cups over the tips of cactus to protect them from frost because that’s where growth comes from. So that’s another option for covering your plants as well.
Insulators
The use of insulators, like mulch, newspaper, straw, and even evergreen branches, is another way to cover your plants and works especially well for plants that are low to the ground. Simply cover your plants with the insulator during the freeze to retain heat and uncover when the weather permits. (Old Farmer’s Almanac)
Lights
You can also use outdoor rated lights or even outdoor holiday lights (incandescent, not LED) to keep plants warm. Just be sure that you’re being safe if you’re using them in conjunction with coverings. Don’t want to start a fire!
Heat Sinks
A garden wall and bodies of water nearby (a lake or pond 1 acre or larger) act as heat sinks that can help defend against frost. But you can also make your own heat sinks by filling gallon jugs with water and setting them out to absorb heat during the day, which they will then radiate at night. Place these next to your plant and cover both the plant and the jugs for maximum efficacy. (Old Farmer’s Almanac, Dengarden)
Good Soil
Good soil can also help protect plants from frost. The Old Farmer’s Almanac informs that “Good soil, full of organic matter, retains moisture, reducing the rate of evaporation. Mulch also helps to prevent evaporation.”
Raised beds/containers
Raised beds and containers warm up more quickly than the ground, so putting your more tender plants or starters in these can be beneficial and help them get through the winter. (Old Farmer’s Almanac)
If you have hanging baskets, place these on the ground so that they can benefit from the warmth radiated from the ground. (Dengarden)
Wrap Fruit Trees
Jill Spencer with Dengarden advises that “most fruit trees have thin barks that are susceptible to splitting when temperatures fluctuate dramatically. Tree wrap will prevent this splitting, which is known as frost crack.” She goes on to describe that you should use multiple layers of burlap, tree wrap, cloth, or weatherproof paper, keeping the wrapping a bit loose, to protect the trunk of your fruit tree.
Anti-transpirant
This is something new to me that sounds like it could be awesome for people like me who forget to check the weather and cover their plants. According to Marin Master Gardeners, anti-transpirants can be found at your local nursery and all you have to do is apply it once to the foliage for protection up to three months and it will seal the moisture into your cold-sensitive plants! I’m definitely going to be looking into this one.
Bring potted and especially tender plants inside
This one seems obvious, but it’s a good idea to think about this when you get a new plant so that you can decide the best placement for your plant, in a container or in the ground. The last thing you want to be doing is digging up a plant in the bitter cold for fear of it not being able to handle the cold. I actually have a plant that lives in my closet all winter and goes dormant until I pull it out in the spring.
Is there any hope if you forget to protect your plants from frost?
Yes! Be patient until spring to see what the plant is going to do. You very well may get regrowth at the base of the plant. At that point, you can prune off any affected parts off of the plant. In the meantime, while it may be tempting to prune them, leave the damaged parts on the plant to help protect the rest of the plant in the event of future frosts. (Marin Master Gardeners)
Go forth and Garden!
So it turns out that some of the things I was doing already are really good for protecting from frost. My garden is in a raised garden bed, and I actually usually water in the evenings already. I also unknowingly picked some pretty hardy plants at the nursery for my garden this year, like lettuce and spinach. And on the advice of a friend, I also started using incandescent Christmas lights on particularly cold nights to keep my plants warm. Hopefully these things will help carry my garden to springtime this year!
Don’t let frosty weather keep you from the garden of your dreams this year! Use these 11 strategies to keep your plants protected from frost! Happy gardening!
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