Protect fruit trees from freezing

Asked February 20, 2015, 5:15 PM EST

I have 5 fruit trees in my yard and with the unseasonably warm weather so early this year a few have budded already, with the low of 22 expected this coming Monday is there anything I can do to protect them? The trees are only a few year old and so not very large, the largest is an apple that is about 10ft tall and maybe 5ft in diameter at the widest part of the canopy

Salt Lake County Utah

1 Response

I am afraid the unseasonably warm spring weather will create problems for commercial fruit growers as well as home orchardists as well. There are a few things you can try but with the low off 22 and with the tree buds swelling, there are no guarantees! Commercial growers will use wind machines, orchard heaters and overhead sprinklers to ward off the cold weather and try to prevent the bud tissues from freezing. Of course, nothing can stop the homeowners from trying to mimic these strategies in the backyard. Hard to mimic a wind machine as the theory is the machines blow hot air down onto the fruit trees (the machines rely on an inversion layer of warm air covering cold air) and drive the cold air away. However, when you plant your trees in a landscape situation, you will want to avoid any low spots in the home landscape where cold air will collect. You want to enhance air movement so the cold air flows away from the fruit trees. Not much of an option for homeowners. Orchard heaters can be purchased by homeowners, but this is still a rather expensive endeavor. I have heard of people placing strings of old-fashioned light bulbs on their fruit trees. The bulbs give off some heat. I have also heard of people constructing plastic "greenhouses", sheds or roofs over the trees to capture or trap radiant heat rising from the ground within the canopy of the tree. Some people will cover the top of the fruit tree canopy with plastic or blankets to trap the radiant heat in the tree canopy. Finally, the watering approach. Believe it or not, when water freezes, it releases heat. So if you can keep a mist or layer of water on the tree, freezing water will heat the tree. Furthermore the ice will provide the tree with a little insulation. Drawback is that ice accumulation can weigh down branches causing damage. I have heard of people having success with under-the-tree irrigation. Again as the water freezes on the ground, it generates heat. Also wet soil under the tree will accumulate and hold more heat during the day and release more heat at night. A combination of all these strategies works best to protect both the fragile buds and the trunk of the tree. The catch is are you spending too much effort to save those buds that develop into fruit this year. Weigh the value of this season's fruit with the value of your effort (for the rest of the spring). If we get an arctic blast, the overall health of the tree may be jeopardized. It may be cheaper to replace any winter-killed trees with winter hardier varieties of fruit trees. Good luck!