Issue: January 26, 2008

Reasons to trim trees


A man came to my door this morning and told me that my trees needed to be trimmed. I think they look fine and sent him away, but then I began to wonder if he was correct. How can I tell if my trees need trimming?

Sandra T.


You probably made the correct decision. There are people who will go door to door soliciting work. Some are legitimate, others are questionable.

If the man was from the city he would have identified himself as such and shown documentation. It is possible the city would require you to trim trees if they were a public hazard. That is one thing you should consider to determine if your trees need to be trimmed. Are there numerous dead branches that could detach in the wind or during a snow storm? If they are over public areas, you might be required to remove them. If they are over your private property, it may still be wise to have them removed for your own safety. Are there branches blocking traffic or clear vision of traffic? They should be removed, even if it is only your egress from your drive that is obstructed. Are the branches so low that they may be struck by passing trucks? These should also be removed for the benefit of the tree as much as to protect the trucks.

Other things to consider that are a more private property matter would be if there is a bad branch connection. If you have two large branches, each growing vertically like trunks or otherwise forming a narrow angle where they are joined, you may have a problem. This can be rectified by proper pruning. The earlier in the life of a tree that such correction are made, the less the damage that is done to the tree.

Any pruning that removes living tissue from the tree has the potential to do harm to the tree. Sometimes it is necessary for the overall health of the tree and to prevent future problems. Nevertheless, any pruning must be done for a proper reason. Trimming just to trim is not good. And, please remember, topping is never a good pruning technique. Do not let any "tree trimmer" top your trees.

If you decide that your trees do need trimming, contact several tree-care professionals listed in the telephone directory. Many will provide free estimates. Ask them what they will be doing and why. It is also advisable to ask if they are certified by the International Society of Arborists. That means they have studied tree care and passed tests to demonstrate their knowledge. You also want to hire someone who is insured to protect you and them in the event of an accident. You do not want to have to rely on your homeowner's insurance in that instance. If they will be working with their feet off the ground, find out if they have the proper equipment for doing this work. While cost is a consideration, it is very important to choose a person who will protect your tree, your property, and his employees when working on your trees. The lowest price may not be the best price.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!