What Causes a Tree Trunk to Split Vertically? Common Causes

Split trunk trees can be both worrying and fascinating to look at. Many people often wonder what causes a tree trunk to split vertically, creating a dramatic effect almost like an optical illusion. 

There are many reasons for the bark splitting, including temperature and moisture fluctuations and incorrect care. In some cases, splitting may indicate issues with your tree’s health. Let’s look at the main reasons a tree is likely to split. 

What Causes a Tree Trunk to Split Vertically?

What Causes a Tree Trunk to Split Vertically

It is important to note that vertical splitting in tree trunks does not always mean the tree is in danger. In most cases, it simply means that the tree is adjusting to its surroundings.

However, if you notice any vertical splits in your trees, it is recommended to take a closer look and ensure no other underlying issues are causing the splitting. If so, contact a professional arborist who can safely handle any underlying problem. 

Here are some common reasons trees split:

Natural splits

The main cause of vertical splits in tree trunks is due to the natural process of expansion and contraction of wood fibers because of changes in temperature and moisture. When the wood fibers contract during a dry spell or cold winter, they can cause splits to open up in the bark as the trunk adjusts to its environment. 

Frost damage

Frost crack is the most common reason that a tree will split. During very cold weather, the tree will contract. As temperatures start to rise, cracks can form in the tree’s trunk.  

Incorrect care

In addition to this natural process, other factors such as over-pruning or incorrect fertilizer application may also contribute to vertical splitting in tree trunks. If branches are over-pruned, it can weaken the tree structure and put too much strain on the trunk. 

Applying too much fertilizer to a tree can cause rapid growth, which can lead to vertical splits forming in the bark. 

The tree is sick

Tree decay diseases may also be a cause of vertical splitting in tree trunks. This is why it’s important to identify the cause of any splits in your trees. If you suspect that your tree has issues, contact a professional arborist to assess the health of the tree and take the necessary steps to protect it. 

How to fix a split tree? 

What Causes a Tree Trunk to Split Vertically

If you have found that a tree has split, it is important to take action and address the issue. Depending on the cause of the splitting, there are several ways to fix a split tree:

  • Prune away any dead or weak branches 
  • Seek professional advice if the tree is sick
  • Use appropriate support systems to stabilize the trunk 
  • Remove the tree if you’re unable to fix or support it

Sometimes, you may need to use a bolt to close the split in the trunk, but be sure to seek professional advice before attempting this. Bolting will involve drilling a hole through the trunk and inserting a bolt to keep the halves together.

Preventative methods

Taking preventive action is also crucial in avoiding vertical splitting in tree trunks. Regularly check your trees and take note of any signs of distress or splits in the bark. With proper care, your trees can remain healthy and strong for many years to come. 


By understanding the causes of vertical splitting in tree trunks, you can help ensure that your trees remain healthy and strong for many years. With proper care and maintenance, even a split trunk tree can be an impressive addition to any garden!