Pruning a Magnolia Tree

Pruning a magnolia tree isn't as difficult as you may think. Arborists recommend that tree pruning only be done in accordance with the tree's natural growth habit. In other words, don't overprune. This is especially true for magnolia trees, which can grow to heights of 60 to 80 feet. Still, it's important to know when, how and why to prune a magnolia tree.

Why Prune a Magnolia Tree?

There are only four basic reasons to prune a magnolia tree.

To Achieve the Best Shape - Train a young tree to grow according to desired shape.

To Improve the Tree’s Health - Pruning supplies more energy for remaining limbs and flowers. It improves overall health of the tree and encourages larger and more flower blooms.

To Improve the Quality of the Tree – Pruning removes unsightly or unwanted tree parts to improve the tree’s overall value or effect in the landscape.

To Restrict growth – Although magnolias growth is slow, they can get quite large over time. Pruning keeps the magnolia tree in check.

When to Prune a Magnolia Tree

According to experts, the best time to prune a magnolia tree that blooms early on last year’s growth is right after the flowers have finished blooming. Depending on the variety of magnolia tree – evergreen or deciduous – pruning may or may not be necessary or recommended.

TIP: Our expert gardening advisor, Susan Patterson warns, "Do not prune mature magnolia trees, as big cuts will not heal and can cause disease problems."

Some botanical garden sources say that deciduous magnolia trees are best left alone to achieve their natural shape and growth. However, shaping magnolias takes longer with deciduous varieties than evergreen ones. For some large varieties of evergreen magnolia, such as the Southern Magnolia, which can grow as high as 80 feet, pruning must be done early when they are young, and repeated as they grow.

The general consensus is that young evergreen magnolias can be pruned by conventional techniques, even severely, without detriment. New growth will come from the tips of the cut branches. If the same technique is applied to deciduous magnolia trees, it may result in growth coming out up to a foot above or below where the cut was made.

TIP: Susan adds, "Use great caution when pruning young magnolia trees. Severe pruning early can cause long-term damage."

General Pruning of Magnolia Trees

Proper pruning tools must be used to ensure consistent, clean cuts. Use pruning shears for cuts up to ¾-inch in diameter. Lopping shears (loppers) should be used to cut branches up to 11 1/2-inches in diameter. Hand saws are best for magnolia tree branches greater than 1 inch in diameter. When pruning a magnolia tree, here are some general tips.

• First, remove all broken, decayed, dead or diseased branches or those that have become a problem
• Cut at the point of origin or back to a strong shoot or lateral branch
• Next, prune for shape, to fill in an open area, or to keep the magnolia tree in check
• Don’t leave stubs and avoid tearing bark on a large branch or trunk
• Cutting back to lateral branches, look for branches with a 45 degree angle to the branch to be cut
• Make slanting cuts on branches that grow upward

TIP: Susan says, "Sterilize pruning tools before using them by placing them in a bucket with hydrogen peroxide for 20 minutes."

In summary, prune a magnolia tree if absolutely necessary to stimulate new growth, to train to a particular rounded-head shape, to keep it from overgrowth and to retain its value. Don’t prune indiscriminately, and keep the magnolia tree’s natural growth and shape in mind.