Beneficial animals Gardening Pruning Trees

Hollow Tree? No Need to Panic!

It is not unusual to find a hole full of rotten wood in the trunk of a living tree or even to find a completely hollow space just inside.

Formerly, homeowners believed that in such a case, you could save the tree by scraping away the rotten wood and digging into healthy wood to “eliminate the rot.” However, we now know that trees are able to protect themselves from rot. They do this by forming stronger, more resistant cells around the wound. This is called compartmentalization. By cutting into healthy wood in an effort to clean the wound, you’ll actually be removing the tree’s natural protection and may even cause the rot to expand.

Hollow tree haphazardly filled with bricks and mortar.
There is no need to fill a hollow tree with bricks, stones, mortar, ciment, etc. They will in no way strengthen it. Photo:

Neither is it necessary either to fill the hole with concrete, bricks, etc., or to paint it with wound dressing, two outdated techniques that cause more harm than good.

Dear or Alive

It’s important to understand that the heartwood of a large tree is dead anyway. It is only the bark and a thin layer under the bark (the sapwood) that is alive. Healthy heartwood may, in some cases, help the tree to better withstand wind, but not always. You often see hollow trees that are very strong. And a hollow trunk certainly doesn’t mean the tree is dying! It can sometimes survive another 20, 40 or 60 years, even a century, depending on the species, as long as it is structurally sound.

To check that out, you’ll need the opinion of an experienced arborist. If they deem the tree to be structurally unsound and if, because of its placement, it could do damage when it falls, you’ll have to have it removed. Otherwise, just leave it alone.

Owl looking out of hole in hollow tree.
All sorts of wildlife depends on access to hollow trees for its survival, like this owl. Photo: FrankFF, depositphotos  

Holes in trees often host all sorts of interesting animals and birds (a hollow Norway maple at my former residence was once home a family of flying squirrels, much to the delight of my kids!). And hollow trees are part of a normal and healthy environment.

So in most cases, when you realize that one of your trees is hollow, just let Mother Nature do her job. She knows better than you do what to do!


Regardless of the material, a tube is always stronger than a solid cylinder. It’s like that in many fields, and in nature too. It’s the case with bones, quills, tusks, horns. Plus, most plants are also an illustration of this, such as the common reed, for example.

The cavity itself is not a problem. It’s simply not a factor when it comes to strength. That being said, there are limits. The opening itself should not be too large or extend too far up and down, like a slit. The tree takes care of reinforcing the circumference of the hole with scar tissues. They begin to appear as soon as the missing branch responsible for the hole is dead, or broken, or cut. Thus, before the wound even becomes a hole, the tree is already taking care of itself.

Paul Emploi

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

6 comments on “Hollow Tree? No Need to Panic!

  1. Pingback: Weeping Willow in Serious Decline  - Laidback Gardener

  2. A hollow in a tree always brings to mind Boo Radley leaving trinkets for Scout and Jem.

  3. marianwhit

    🙂 And aesthetics…western society is obsessed with straight and perfect trees…which mean they all look alike. I love the Japanese concept of “wabi sabi”…an understanding of the beauty of nature and how the whole process offers possibility for beauty…even aging and decay, which trees can do for long time!

  4. Great advice. Too frequently we are concerned about the aesthetics of a tree or the ‘potential’ for harm. Yet in the wild there are a whole lot of hollow trees that have stood for a very long time. In our area we have owls, woodpeckers and a number of cavity dwelling birds all happily ensconced in tree hollows. Love to have them.

  5. marianwhit

    That photo with the bricks! Breathtaking example of the human “need to control”, a natural urge, but often done without “doing the homework”. 1) Why does the hole bother me? What is motivating me? 2) Is there harm? Is there danger? 3) What is the “tree’s perspective”? What is the wildlife that uses the tree’s perspective? 4) What science is available on the subject? Are my sources of information reliable? 4) What would be lost or gained by doing something…or nothing? That is kind of the process I go through to determine if I need to create a bunch of work for myself, or spend money to hire someone.

    An example…when young and stupid, I paid thousands of dollars to two guys with chainsaws when my 30+ mature spruce started to all die at once. Then a friend said “You know those trees tend to come down in thirds, right?” Argh…so I am careful with the ones around the house that may pose risks in storms, and the rest do what they want…and I have a lot of wonderful woodpeckers! I married the man that gave me the good advice! Hope you are doing well Larry!

  6. Pingback: When A Trunk Cracks… | Laidback Gardener

Leave a Reply

Sign up for the Laidback Gardener blog and receive articles in your inbox every morning!

%d bloggers like this: