Winter desiccation of evergreens
Despite the cold, harsh conditions of winter, your evergreens are still transpiring and need to have that lost water replaced. If moisture lost through the needles is higher than what the tree is taking in through its roots, the needles will turn brown in the spring. This is called “winter desiccation”. Typically you’ll see browning on the ends of branches. In severe cases it can be the entire side of a tree, which usually faces the prevailing wind. When they’re damaged by desiccation there’s no going back, those tissues are dead.
Nicole Stoner is an Extension educator at the University of Nebraska. She says most people ignore their trees during the winter, and advises getting out the hose when temperatures rise above 40-degrees.
"Go out mid-morning once the ground has thawed a little bit, and early enough in the day so that the water can penetrate down into the soil before freezing occurs again. You don’t want it puddling on top of the ground when that freeze occurs overnight," says Stoner. "I like to say November, December, January, February, get out there one time each month. If it’s dry, if we’re not seeing snow cover, get out there and water those trees a little bit."
Evergreens don’t need as much water as they do during the spring and summer, but try to get some moisture to the roots.
"Most of your tree roots are going to be in the top 12”-18” of soil," says Stoner. "So if you’re watering a slow trickle for, you know, a half-hour to an hour, about an inch of water so that it gets down into where those roots are and can keep those going, we do want to get out there if we can. Even full-grown trees need water, especially in drought situations."
In most cases, brown needles are just an aesthetic issue and only need selective pruning. But severe damage can kill the underlying branches, and you may have to remove the tree.
Learn more about winter desiccation and what plants are susceptible
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