When Should I Prune My Trees?

Jason LaRose
Staunton, VA

-This is perhaps the most frequently asked question we get.  So let's break it down.

Tree service companies by nature are busiest in the spring.  After being cooped up inside all winter, which is a very reasonable 4 months here in Staunton, VA, yard work becomes a top priority for homeowners.  Perhaps you are out pulling weeds in the fine sunshine and you notice the large pin oak (Quercus palustris) in the front that the previous owners planted back in the 70s.  It somehow managed to escape the topping expertise of the local "trimmers" and it has a rather nice, albeit crowded upper crown.  The branches are reaching for the sun, and with no competition nearby they are getting plenty of it.  The lower 1/3 of the tree is a different story.  An interwoven mat of sickly, half dead and crispy branches meets the eye.  Something must be done.

A phone call to your local certified Arborist, an appointment, and you're on the schedule for a crown cleaning and thinning before barbecue season sets in.  Unless...you don't get around to calling till after the 4th, and the company has a very respectable "backlog" of clients all anxious to get the crew 'round to them.  Your Arborist knows full well that the phone basically stops ringing between Thanksgiving and Christmas, and might not start again till the following spring.  Maybe he can give you a great deal on pruning this tree, if you wait till January?  If he is an honest sort you may be inclined to agree, and perhaps you all reach an agreement on structure pruning the redbuds (Cercis canadensis) you planted back in 2012.

Perhaps the fellow you called isn’t a certified Arborist, nor a CTSP, and has never even heard of the Tree Care Industry Association and its ongoing mission to promote safety, education, and standards in the field of arboriculture? GASP.

Either way you can easily imagine how dirty rumors like “you should only prune your trees in the winter” get started.

The truth is that the only “bad” time to prune a healthy tree is the two week period in which it is flowering, and during times of moderate to severe drought.  The exception is pruning fruit trees to maximize production.  I’m not an expert on pruning for fruit production and am not going there.

To be clear, pruning cuts made at different times of the year will generate growth in different ways.  The Godfather of modern arboriculture, Dr. Alex Shigo, said it best “pruning is not about what you take, rather about what you leave behind.”  Shigo mapped the process by which trees protect themselves after an injury like pruning.  He coined this system CODIT, controlled order of decay in trees.  

The most important factors to take into account for a pruning job are (in no particular order):

1. Client goals
2. The position of the cuts in the crown i.e. tips, trunk, laterals etc
3. The age of the tree

     4.   Size of the cut/size of wound the tree must now seal
     5.   Cleanliness of cut and placement- No stubs, no flush cuts
     6.   Volume of leaf bearing material being removed, no more than 20%
-Anytime is a good time to remove dead wood or crown clean.

As always these tasks should be carried out by a trained professional, no ladders, no loppers, no gas powered pole saws.  Even a bucket truck can’t get everywhere in every tree, trust me I’ve tried. Climbers that love to climb will do the best job, the bigger the tree the happier he will be.  

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