How to Tell How Old a Tree Is: A Brief Guide

how to tell how old a tree is

Do you have a beloved tree in your yard or garden that has thrived there for as long as you can remember? Knowing the age of your specimen can help you grasp the full scope of its history and appreciate it even more — but how exactly do you find out?

As Denver’s professional tree service, we at Bear Creek Tree Service can offer insight on how to tell how old a tree is. Keep reading and discover something new about your living landscape!

Count the Rings

Did you know that all trees have ring-like marks inside their trunks? Every year, they grow a new layer of wood, which produces one more ring. If you recently cut down your specimen, you can count the rings from the freshly exposed surface.

This method isn’t ideal if your tree still stands, though. Some arborists use special tools called increment borers to penetrate the bark and take core samples to count the rings. When done correctly, it won’t cause any lasting damage.

Measure the Trunk

One way you can get a ring-count estimate is to measure the circumference of the trunk at breast height and calculate the radius and diameter of the tree. Then, subtract 0.25, 0.5, or one inch off the radius to factor out the bark (the thinner the bark, the less you need to subtract).

Now that you have a rough radius of the trunk, you need to determine the average ring width of your specific tree species. For instance, oak varieties have 0.2 inches per ring. Divide the radius of the tree by 0.2 to get a rough estimate of its age.

Estimating Through Growth Factor

Another way how to tell how old a tree is is by multiplying the diameter you measured in the previous step by the growth factor of your tree species. Here’s a quick reference guide of popular varieties and their average growth rates:

  • Douglas Fir: 5.0
  • Colorado Blue Spruce: 4.5
  • Aspen: 2.0
  • Red Maple: 4.5
  • American Sycamore: 4.0
  • White Birch: 5.0
  • Pin Oak: 3.0
  • Linden: 3.0
  • Kentucky Coffeetree: 3.0
  • Bradford Pear: 3.0
  • Austrian Pine: 4.5
  • Red Pine: 5.5

Count the Whorls

Do you have a coniferous or evergreen specimen? You can count its whorls — that is, the circular row of branches originating from the main stem. Don’t include any irregular branches between two whorls. Add about two to four years for each whorl, and you’ll estimate the age of your tree.

Consult a Local Arborist

Even similar trees grow differently in different environments, making it difficult to calculate the exact age. Why not let an expert handle it? We at Bear Creek Tree Service know how to tell how old a tree is. Plus, we can check its overall health and provide appropriate care to keep it thriving. Give us a call at (720) 299-1409 or read our blog and discover the best time to plant trees, easy fungus treatments, and other useful tips.

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