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These trees were planted by a gardening company in our courtyard. We would love to match the trees' ages with neighborhood kids' ages so they can see the trees growing along with themselves over the years. The childred will be able to attach their photo to 'their' tree. Unfortunately, the gardening company was unable (or unwilling) to give me estimates on the tree ages. Who could throw in some guesses on the ages of these trees?

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  • Nice idea. But does it really matter if the plant is exactly 4 or 5 or six years old? Tree age is always an estimate until you cut it dead.
    – Johannes_B
    May 14 at 5:31
  • It does not need to be exact. One-off is totally fine. But it cannot be invented, the kids need to trust it.
    – Hauke
    May 14 at 14:48
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There are a couple of ways you can go about this.

One way is to use the formula developed by the International Society of Arborists for calculating the age of a tree from its diameter. You measure the diameter of the tree "at breast height" or about 4 feet off the ground (actually, measure its circumference and divide by 3.14). Then you find the appropriate growth factor for that tree type, and multiply it by the diameter to get the tree's age.

Tree Species | Growth Factor
Red Maple Species | 4.5
Silver Maple Species | 3.0
Sugar Maple Species | 5.0 
River Birch Species | 3.5 
White Birch Species | 5.0
Shagbark Hickory Species | 7.5  
Green Ash Species | 4.0 
Black Walnut Species | 4.5
Black Cherry Species | 5.0
Red Oak Species | 4.0
White Oak Species | 5.0
Pin Oak Species | 3.0 
Basswood Species | 3.0
American Elm Species | 4.0
Ironwood Species | 7.0
Cottonwood Species | 2.0
Redbud Species | 7.0
Dogwood Species | 7.0
Aspen Species | 2.0

That method is more accurate for older trees, and may not be as accurate for your young trees. Also on younger trees, it can be challenging to measure the DBH because there may be branches in the way. But, since all you really need is an estimate, this may be fine. Plus it gives you an activity to do with the children.


Another method is to read the tags on the trees to find out what nursery or tree supplier they came from. It may say on their website how old their trees of each species typically are. Or you can contact them and ask. This might require some interpretation on your part, to figure out what size of tree your gardeners planted.

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  • Are the species you listed the species that are shown in the pictures? Which one is which?
    – Hauke
    May 14 at 14:49
  • You posted 18 different tree photos. That's a bit much to expect to have them all ID'd in a single question. I suggest separating them out into separate questions, with one tree per question, and better photos including close-ups of leaves. The only one I can ID with confidence from those photos is number 12, which is a dogwood. When you go to take leaf photos, check the trees to see if they still have labels with species names on them. Number 6 seems to have a label.
    – csk
    May 14 at 14:55
  • But even with close up photos of the leaves, no one can predict the precise age of the plants.
    – Johannes_B
    May 14 at 17:17
  • @Johannes_B The leaf photos are necessary for species ID, which will allow them to use the formula from the ISA to calculate approximate age. Yes, it will be approximate. I addressed that in my answer.
    – csk
    May 14 at 17:39

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