A general landscaping company should be able to trim most trees, provided they have the right equipment. Sometimes, though, you may want to hire a more qualified professional, called an arborist, to trim your trees. Arborists know all there is to know about trees and their structure, their biology, their health, and their care. As such, they are capable of using more specialized trimming techniques to meet a tree's unique needs. But when do you need to call an arborist, and not just your general landscaper? Here are a few situations.

Your tree has a disease.

Does your tree have spots on some of the leaves or cankers on some of the branches? Some tree diseases can be eliminated by trimming away the damaged branches. But there are other diseases for which this is not a cure and may, in fact, just make the disease worse. It's a good idea to have an arborist come to care for the tree. They can determine which disease is at fault and carry out the recommended treatment, whether that's trimming the tree, spraying it with fungicides, or both. Arborists are also very well-versed in the sanitation techniques needed to keep prevent spreading the disease to other branches when trimming away the diseased ones.

You are trying to make a tree much smaller.

The more growth you remove from the tree, the harder it will be for the tree to recover. So, if you have a really large and overgrown tree that you hope you can really bring down in size or reshape, you are better off leaving this to an experienced arborist. They'll know which branches to remove and which to leave. They'll also know when to best schedule the trimming to ensure your tree stands the best chance of recovery. Some tree species recover from extensive trimming more easily in the spring, and other in the fall.

Your tree is a rare or valuable species.

If you have a rare tree species, like a Florida yew, a monkey puzzle tree, or a ginkgo, then you should probably hire an arborist to trim it. Many of these trees have specific needs as far as when they need to be trimmed and how they are best shaped. The average landscaper has probably not encountered these trees before and may not know how to best trim them.

Arborists are a wealth of knowledge, and they are often the best choice for tree trimming if your tree is a rare or valuable species, if your tree is diseased, or if you're trying to make the tree substantially smaller.