Pruning for Your Tree's Future

Take a look at your trees - especially any that border the sidewalk in front of your house or grow over the street. Branches less than 6 to 8 feet from the ground should be removed.

I was speaking with a neighbor of mine a few weeks ago about such a branch and discovered that he just assumed the tree would get taller and those branches would grow up as the tree height increased. In case you have that same notion, let me dispel it immediately: a branch 4 feet above the ground now will always be 4 feet above the ground. Trees grow each spring from the top buds up, and the side branch tips, but not from the bottom up out of the ground. Of course children in the mood to climb trees will appreciate your leaving as many low branches as possible, but trees near the street and sidewalk or property line can be inconvenient or may even be obstructions.

First, branches over the sidewalk need to be pruned to avoid poking pedestrians. Those hanging over the street are better pruned by you or your city street tree department than ripped off by a truck driving by. Chances are pruning will cost less that taking care of the property damage a low branch may cause a passing vehicle. In addition, pruning those low branches is best when the tree is still young: the smaller branch size will leave less of a scar on the tree, and therefore new callous growth will close over the injury faster.

In fact, I have a little poem about why we should prune: You don't want to poke a pedestrian's eye; to avoid trucks scraping when they're passing by; leave space for your friends to park their car; Prune early for the tree, to avoid a scar.

In addition to pruning low-hanging branches, additional pruning will probably be needed. Without our help, a tree can self-destruct over time. In a case where two branches are growing too close together, one will eventually be squeezed out of place, die and eventually break off. The broken and/or dead branch could be the better of the two for your tree's appearance.

How do you know which branch to prune? Well, once you've removed low branches hanging over the sidewalk or street, start with those that are crossed and rubbing each other. The branch most perpendicular to the trunk is the one to try and save, as it forms a mechanically strong junction with the trunk.

Next, look for spacing between branches. I like to see 12 inches, if not more, between branches - one above the other. That goes for those trees that grow opposite branches as well as alternate branches. We also don't want too many branches radiating from the same height above the ground. These may also pinch each other.

If you have to select one branch over another in order to achieve optimum spacing, consider the health of the particular branch, the variety of positions of all the branches on the tree, and the tree's overall surroundings. If a healthy, seemingly well-placed branch is headed towards your shed or your child's swing set, sacrifice it and allow a better-placed branch to continue growing.

You should also take into account the need to properly space trees. If you are planting young trees in an area that you want shaded now, plant a "sacrifice tree." In other words, you can purposely plant trees too close together if you intend to cut the middle one down when they get tall and begin to crowd one another.

When you prune branches, cut just beyond the branch-bark collar. This is a slightly swollen ring of tissue at the point where the branch joins the trunk. Do not cut the branch flush to the trunk. A flush cut opens a larger scar and you will be cutting behind the wound closure tissue that trees have. Cutting slightly further out on the branch (just past the collar) is better for the tree because the wound will close more quickly and allow less time for decay to set in.

Don't feel like you have to make all these decisions alone. There are lots of competent arborists out there ready to help you. Give them a call if you are unsure of the needs of a particular tree.

Don't leave the pruning to Mother Nature. Quite often she's not as particular as we are with each individual tree.