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A society grows when the old plant trees whose shade they will never sit in

That's a good old Greek proverb above.

In Florida there are trees everywhere.

Of course it's possible to have a very old site with young trees on it, but old trees often mark places where interesting things happened a long time ago.

So we at HCNF often find ourselves wondering: How old is that tree?

There is a HUGE variation depending on soil type, moisture, and so on. But you can start with a very rough guess by using this technique, from the International Society of Arborculture:

  1. With a tape measure, find the circumference of the tree about 4.5 feet off the ground. Make sure the tape doesn't pass over any burls or bumps.

  2. Find the tree's diameter by dividing that number by pi (see! your teacher was right, that math really was good for something). In the likely event that you don't want to pull out the calculator app on your phone, just divide by 3.

  3. Multiply that diameter by the Growth Factor for that type of tree. Try the table below. If you don't know the type, use 4.

  4. Your answer is the VERY ROUGH age of the tree in years

Circumference x 1/3 x Growth Factor = age in years

One of our members has a house built 40 years ago. There is a hickory tree in the yard, clearly planted at the time of building, that measures 17 inches (43 cm) around, so

(17 inches ÷ 3.14) x 7.5 years/inch = 41 years

(43 cm ÷ 3.14) x 3.0 years/inch = 41 years

Pretty good! shows that this house is on land that was previously part of a farm, and that plowing stopped and trees started growing back in about 70 years ago.

86 inch circumference oak = 82 years

55 inch circumference sycamore = 70 years

Not too shabby at all.

The Fairchild Oak in Bulow Creek State Park has a 24 foot circumference, leading experts to estimate that it is well over 400 years old (live oaks are notoriously tricky when it comes to growth factor - it may be much older than this!)

The Fairchild Oak

Identifying your tree:


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