Here's why expert arborists recommend pruning your trees in the winter

Just like humans, trees should get regular "haircuts" to stay looking and feeling their best.

For trees, this is called "pruning," and it's the process of selectively removing or trimming problematic or unhealthy branches to keep a tree healthy and growing.

While many humans prefer getting their hair cut in the warmer summer months, expert arborists have found its best to prune trees in the winter, when they've entered their dormant phase.

We spoke with arborist Adam Passo, district manager of Southwest Milwaukee's Davey Tree service, about why it's best to prune your trees in the winter and how to go about doing it.

Here's what we learned.

Why should I prune my trees in the winter?

After trees lose their leaves in the fall, it's much easier to see and remove problem branches.

"When we're pruning in the winter, it's a lot more efficient," Passo said. "And without all those leaves, it's a lot less debris, so it's more cost effective for people to do work."

Additionally, in the winter, trees enter their dormant phase. The trees are still alive, but not actively growing, and their inner workings slow down. Dormancy helps trees prevent loss of water and nutrients and avoid damage from cold temperatures.

It's also virtually impossible for diseases ― like fire blight, Dutch elm disease and oak wilt ― to spread while trees are dormant, Passo said. So lawn owners and arborists don't have to worry about contaminating their pruning equipment and spreading disease.

More:You probably shouldn't rake up all your leaves. Here's why, according to experts.

What are the benefits of pruning your trees?

Removing unhealthy and weak branches from trees allows them to direct more nutrients and resources into healthy branches, allowing those limbs to grow even stronger and healthier.

Additionally, weak branches can pose a safety hazard because they're more likely to fall on people or buildings.

In natural settings like forests, trees essentially prune themselves by "shading out" excess branches, Passo said.

"You'll have understory limbs in a forest that are all competing; it's just one big competition in the forest for light and resources," he said. "So a lot of those lower limbs will not be producing as much because they don't get enough light, and the tree will just cut off the water, basically, to those limbs, and then they die."

While this works in the dense forest, most people's yards do not have enough shade for pruning to happen naturally.

Because of this, "every limb ... has the ability to live, even though maybe it shouldn't necessarily, because it's weak or has poor junctions," Passo said. Weak limbs are prone to storm damage, he added; that can result in storm damage being far more common in yards than in nature.

What are some signs a branch might need to be pruned?

There are many signs that a branch might be weak, damaging to its tree, or a threat to nearby people and property.

Here are some clues that a branch might need to be pruned, Passo said:

• Scaffolding, also known as limbs that are growing too closely on top of each other. Often, a weaker limb uses another limb to support all of its weight and wouldn't be able to support itself on its own, Passo said. Limbs like these should be removed.
• Limbs that are rubbing together should be pruned.
• Bad junctions where the branches are pushing on the trunk, rather than growing "nicely away from the trunk" should be pruned because this competition between the limb and the trunk can cause decay.
• Generally, limbs growing toward buildings should be removed.
• Limbs that are clearly structurally weak, dying or diseased should be removed.

How much should I prune my trees?

While pruning is extremely important for maintaining a tree's health, there is such a thing as too much pruning, and that can cause problems.

Passo said you generally should not cut off more than one-third of any limb or one-third total of a tree; otherwise, the tree will send out stress signals. Being under stress can put a tree at risk for many problems, including insects and leaf diseases.

Making sure you don't prune too much and stress out your tree is another good reason to prune in the winter because you can more accurately see how much you're cutting off without leaves in the way, Passo noted.

Can I prune my own trees?

Lawn owners can do light pruning on smaller trees, Passo said. However, they should be sure to consult expert sources, like an arborist or reputable websites, to ensure they're making the correct cuts on their tree. Incorrect cuts can further damage, or even kill, a tree.

Larger pruning jobs that involve climbing trees should be left to professional arborists who have the necessary training and tools, like ropes and saddles, to complete them safely and without damaging the tree.