The term frost blanket is used when talking about many different types of plant or crop coverings utilized when the forecast calls for low, typically below freezing, overnight (or sometimes even daylight) temperatures and you have outdoor plants that are vulnerable to such conditions. The easiest and fastest solution is to cover the plant or row of crops with a ‘blanket‘, more specifically a frost blanket.
You can buy a professionally manufactured frost blanket, sometimes called a thermal blanket, thermal row cover, or garden fabric. They are made from a variety of materials(mostly polypropylene) that come in different weights and sizes. Some ‘breathe’ well. Some don't.
My mom used to use our old sheets and a few well placed rocks and that always seemed to do the trick on her front yard flower bed. It wasn’t the most aesthetically appealing but it was only temporary.
Savvy gardeners have become more frugal and more creative in what they have used for a frost blanket.
Some gardeners use cardboard boxes although I can imagine this option to be slightly more difficult to ‘drape‘ and to pin down, but surely work in a pinch.
A burlap sack is a good frost blanket and is able to breathe. In a pinch plastic sheeting(as in left over from the dry cleaner!) will work if the low temperatures are not too drastic. If you are really desperate you can even use newspaper as a frost blanket!
Others use old blankets or sheets like my mother used to do and again this works well. Along the same lines, beach towels will work. Even old curtains!
I like to go the route of my mom’s old method of using her sheets and blankets but this only works well if the fabric doesn’t get wet. If this happens evaporative cooling might lead to colder temperatures surrounding your plants(under the blanket) so be sure the forecast doesn’t involve much humidity. If you decide to do the same, the fabric must be removed during the day to allow the soil to warm up again while the sun is up. Then you will have to replace the fabric before nightfall but before replacing it I also like to water the garden lightly. The water will help to retain the heat in the soil longer. Another tip from a frugal gardening friend was to place a bicycle inner tube filled with a bit of water in your garden bed before you place the frost blanket back on top. The black inner tube would have absorbed heat throughout the day and the water retains it. At night the inner tube will give off added warmth under the frost blanket.
I like any idea that involves recycling and less cost…and a little bit of science!
While using old blankets or towels or even sheets you must consider how heavy they are and if they are going to be damaging to the plants below. You can prop up the blankets using old tent stakes or any kind of makeshift stake. You can also drape the fabric over hoops made out of PVC pipe or hose. Another friend admitted to using hula hoops which I thought was a very good idea for a smaller row. This would be considered a hoop tunnel so not exactly a frost blanket any longer but it does the same thing.
A solution to the heavy weight issue is something called a floating row cover which also is a type of frost blanket. It is made of a lightweight fabric that can lay directly on top of a row of plants.
It is also able to transmit light so it can be left on the plants for a longer duration than the sheets out of the linen closet!
I hope this list gets your creative juices flowing. It doesn’t cost much to create a frost blanket so no excuses about getting into that garden a wee bit earlier than usual! Think of those ripe tomatoes you’ll be plucking from the vine in June!