Frost Blanket! Freeze Blanket! Row Cover! Frost Protection! Whatever you call them, you need to stock up on them, or pull them out of storage, before we actually do get any freezing weather or frost. November 1 is a good deadline to be prepared. We often experience early, but light freezes in November. And once we do have a legitimate freeze forecast for the region, every retail outlet that sells such products will be sold out in a flash. That’s why I implore you to act early!
If you’re not familiar with the ‘hows’, “whys’ and ‘whats’ of Frost Blankets, let me explain in detail on why I think you should be stocking up on them. It is mainly their unique ability to create a 5-6 degree (in some cases 6-8 degrees) temperature difference between the outside elements and what’s underneath that cover. That’s because Frost Blankets and their cousins are made from spun fabrics from polypropylene material that transmits 70 percent of the available light, which helps to keep the heat underneath the fabric, on light freeze nights.
Meanwhile unlike plastics and blankets, these fabrics allow for air and moisture to percolate down to the ground around the plants. And the temperatures don’t have to be freezing or below to benefit from the use of Frost Blankets; as the common name suggests, they are great at protecting against frost damage on those mornings where the temperatures are slightly above freezing but the moisture and humidity are just right to create a layer of frost.
And while sheets and bedspreads, cardboard boxes and curtain material can help to provide several degrees of temperature difference, you have to remove them each day the temps get back above freezing because you can’t keep a plant covered for more than two days unless it is the woven-fabric kind.
For those who still mistakenly cover with plastic, let me try to explain why that’s never a good idea. First it’s almost always too thin to provide much more than 1 to 2 degrees difference in temperatures. Plastic that touches the plant is even worse because it’s like a conduit for the freezing weather to be pulled straight into the plant, since it can hold moisture against the plant tissues and cause more serious freeze damage.
And for those who worry about “Wind Chill” and thinking that if the temperature gets down to 29 but the wind chill is 22, then what good is the Frost Blanket at 5-6 degrees warmer? Unlike human skin, “wind chill” has no effect on plants.
So, whether you’re like me and already have plenty of Frost Blankets in storage, or whether you’re finally willing to invest in that change — pull ‘em out or get to the store and stock up.