Winter is the time when our family enjoys the warmth from the firewood we have gathered, and prune the branches on the trees we planted. This is the best time to prune because the trees are dormant, and the insects, diseases and fungi that would normally infect open wounds in trees (like those created when a branch is cut off) are not active or in the air.
Pruning has become a family tradition, and our goal is to increase the value of our trees by creating more knot-free wood in the bottom or butt log. We also do some pruning of the trees around our buildings for aesthetic reasons, and to decrease the chances that wildfire will climb the trees (by decreasing the fuel in the lower part of the tree).
Some other reasons you might want to prune trees include:
To remove multiple leaders (or top stems)
To improve on the straightness of the tree
To remove dead or diseased limbs (you can remove dead branches any time of the year)
To increase fruit production and open the canopy (fruit trees)
We focus our pruning on the trees that will give us the highest return on this investment of work. That means primarily the oaks and walnuts, but we also prune the red pine we planted. We would like to prune all the hardwood trees on our property (not just those we planted), but don’t really have the time to do that. However, when we are working in the woods and see a nice tree that would benefit from the removal of some branches, we will spend a bit of time on that one. The guideline we follow for the trees that grew on their own is to prune the best, most vigorously growing trees.
For the trees we plant, we check them out after each growing season to see how they are doing and make some small cuts to improve their quality later in life. When they are small, this usually means identifying what will be the main leader (or the top most stem) and remove any competing branches. We will continue to focus on the top of the trees until they get to be 8-12 feet tall and then start pruning the bottom part of the tree. This may be useful when dealing with deer browse, as well. If deer have eaten a main leader, you can prune to select a new leader.
When the trees were young and small, our focus was on creating a dominant main leader and keeping the form of the tree straight. When the trees get to be 8-12 feet tall, our focus turns to keeping the bottom part of the tree free of branches. But we don’t want to cut too many branches, especially when we just start pruning the bottom. The guideline we follow is to remove no more than one-third of the live crown of the tree.
Some other guidelines we adhere to are to prune branches while they are still small (ie less than three inches across), to keep the knots small. When the trees get bigger, we prune to a minimum height of 9 feet and when possible as high as 16 feet, but usually settle for 12 feet. We have a powered pole pruner and that makes this work much easier.
We have a long tradition in our family of the elders teaching the youngsters how to plant trees and how to prune trees. We usually wait till the kids are a bit older before showing them how to prune, even though they are usually itching to use the pole pruner. The first mistakes the newbies make while pruning is to leave to big of a stub or cut the branch off flush to the main stem. Both of these will leave a sizeable wound that can greatly detract from the value of the tree.
The process we teach the kids for pruning follows three steps (see the figure):
Step 1 – make a cut on the under side of the branch about 12 inches from main stem and 1/3 of depth of branch
Step 2 – make a cut downwards through the branch just past the first cut
Step 3 – cut off the remainder of the branch just outside the branch collar and bark ridge
Pruning is a lot of work, but in the end we have some really good looking trees, and get to spend some time together out in the woods.
Check out this publication for a detailed description on pruning: http://dnr.wi.gov/topic/forestmanagement/documents/pub/FR-256.pdf