Magnolia trees can benefit greatly from proper pruning done at the right intervals. Like with any tree, the key to good pruning or even adequate pruning is to not overdo it and harm the plant’s growth potential. This is especially true with magnolias, as these trees can reach heights of 60-80 feet in their lifetime.
Benefits of Pruning
Pruning in its most basic definition is the removal of unsightly or unwanted tree parts. Unwanted parts aren’t uncommon with these trees. Since magnolias get so large, one of the most frequent reasons to prune a magnolia is to restrict its growth so that it is either more manageable or not an obstruction in its surroundings.
Removing unsightly parts can serve additional purposes as well. Considering blemishes on a plant are often leaves, branches, or blossoms that are dead or infirmed, pruning improves not only the aesthetic quality of the tree, but also its health.
By removing weakened or dead limbs through proper pruning, more of the tree’s energy can be focused towards cultivating the healthy branches and flowers that remain.
When to Prune a Magnolia Tree
The general consensus among experts is that the best time to prune a magnolia tree is right after the flowers have finished blooming. However, that’s pretty much where the consensus ends.
Depending factors such as variety, be it evergreen or deciduous, the age and maturity of the tree, and what shape you may be training your tree to grow into, the ideal habits for pruning vary.
The first task in any pruning job, regardless of variety, should be to remove all broken, decayed, dead, or diseased branches or anything that looks to have become a problem.
Magnolia trees of this variety grow quickly and grow tall, with species like the Southern Magnolia growing as tall as 80 feet under ideal conditions. As such, young evergreen magnolias can be pruned using conventional techniques without any detriment.
Similarly, because of the evergreen’s durability, if you wish to properly dictate the shape it will grow into, pruning must be done early and must be repeated as it grows. New growth will continue to come from the tips of the cut branches.
When pruning for shape, begin with a cut at the point of origin or back to a strong shoot or lateral branch regardless of shaping, and only then prune for shape, to fill in an open area, or to keep the magnolia tree in check.
Some botanical garden sources say that deciduous magnolia trees are best left alone to achieve their natural shape and growth. As such, shaping magnolias takes longer with deciduous varieties than evergreen ones.
Unlike evergreens that sprout new growth from exactly where they are cut, the same technique applied to deciduous magnolia trees will result in the growth appearing up to a foot above or below where the cut was made.
Deciduous trees require more caution and precision when pruning, as severe pruning can cause long term damage.
When cutting back to lateral branches, look for branches with a 45 degree angle to the branch to be cut. Be sure to make slanting cuts on branches that grow upwards.
When to Stop Pruning
Regardless of the differences the two varieties have as they grow, at a certain age, any mature magnolia tree should no longer be pruned, as big cuts will not heal and can cause disease problems.
Tools for Pruning
Proper pruning tools must be used to ensure consistent, clean cuts. The best means of choosing the proper cutting tool is to determine the thickness of whatever piece of the plant you wish to remove.
Use conventional pruning shears for cuts up to 3/4 inches in diameter. Lopping shears or loppers should be used to cut branches ranging in thickness from 1-1 1/2 inches in diameter. Hand saws are best for magnolia tree branches greater than 2 inches in diameter.
As you can see, there are some gaps between the ranges these tools cut best at. Examine the hardness and resistance you feel in your specific branches and use your best judgement when your diameter falls between the ideal zone for two tools.
Sterilize pruning tools before using them by placing them in a bucket with hydrogen peroxide for 20 minutes.