Ask Mr. Smarty Plants

As you might suspect, different species of tree grow at different rates. Some are fast growing like Arizona ash and are prized by developers and homeowners for their quick growth pace. Others, like many oaks, are known for their slow growth. In general, their is an inverse correlation between a trees growth rate and its longevity. Fast growing tress tend to have shorter lifespans and slow growing trees longer lifespans. IMr. SP doesn't know where you got the 3.5 percentage but its is pretty easy to tell how fast your tress are growing. Simply examine a twig on any tree and note the terminal bud covered by small scales at the end of the twig. This is the growing tip of the twig. Now work backward until you find a spot on the twig encircled by several scars. These scars are left by the scales that covered the terminal bud in the previous year. The distance between the terminal bud scale scars and the terminal bud equals one years growth (see illustration). You should examine several twigs on the same tree to get an overall idea of how much growth occurred on that tree in the previous year. Using this technique compare the growth on different species to get an idea of how fast your trees are growing.