University of Vermont Extension 
Department of Plant and Soil Science

Winter News Article


Dr. Leonard Perry, Extension Professor
University of Vermont

How to prune evergreens, how to handle a potted evergreen tree after use indoors for the holidays, and how to discourage woodpeckers, are some of the common outdoor winter gardening questions.

If you have a tall Norway spruce, or similar evergreen such as balsam fir, and want to reduce its height, how do you go about this?  If it is too tall to get to the top comfortably, either on a sturdy ladder or with a pole saw, then hire an arborist.  It is not worth the risk of injury or falling just to save some money. 

By cutting the top out of a tree, even one about ten feet high as I have done with some balsam firs, you will find them getting more bushy over time.  And you will see in a year or two one of the upright side branches near the cut top start growing upwards to become the new central leader.  This is caused by redirecting of plant hormones that are responsible for such trees growing upright.  So, in time, you will have a tall tree once again without further pruning.

Winter is a good time to prune evergreens, provided it is warm enough to work outside comfortably.  Although the cuts you make by pruning wont heal until Spring, diseases aren't active until then either.  In Spring, the wounds will heal rapidly as growth resumes. 

Some have a small Norway spruce in a pot they used for the holidays indoors.  What do you do with it then to keep it healthy?  Such trees, purchased to be planted outside after the holidays, should be placed outside into a prepared hole already dug, ideally.  If you didn’t get such a hole dug, and the ground is frozen, it is still best to place such a tree outside.  These trees need cold, and if left inside too long they will try to grow, and not succeed.  Needles will drop off, and trees usually will die.

If placing such trees outside, cover the pot well with soil and mulch until you can plant in early spring.  If the tree was inside for more than a couple weeks, and you see buds starting to grow, new growth may be tender and injured from cold.  It is best to leave such trees in an unheated garage or shed, but with some light and kept watered.  Or, if placing outside, protect by wrapping with several layers of burlap.     

If you have woodpeckers feeding on your suet and peanut feeders, but then making holes in nearby trees, what should you do?  Sometimes they are looking for insects, so check to see if there are insects under the bark of the trees that you can deal with in spring.  If not, and the trees are valuable, you might spread a commercial product such as Tanglefoot on the bark.  This is designed to not hurt the tree, yet discourage such attacks.  Don’t use home remedies, such as petroleum-based products, that can injure the bark and kill it.  If just a few trunks, you can try wrapping them with screen or fine wire mesh.

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