Bigger is usually not better when planting new trees

I understand that one of the prime reasons that folks here want to have trees is for the shade they provide during our hot summers. And I also understand that, all other things being equal, big trees make more shade than little trees.

So when the subject of planting a tree comes up, they’ll point to a favored spot and often ask a natural question: “How large a tree can I plant there?” It seems to be a logical question, but the answer is not quite that simple; a little more complex than you might think. Usually implied in their question is the idea that “bigger is better,” but that is not always the case.

First, in most situations there is an obvious real limit on the size that can be installed. The limiting factors are not only physical space on the site, but also cost, availability and the physical limitations of installation equipment. Eight- to 10-inch trees can be installed on a site with a large tree spade. And, of course, even larger trees have now and then been successfully i nstalled when money for process, equipment and manpower is no impediment.

But there is another and maybe even more practical aspect to the question of “How big?” It is the matter of survivability and performance.

If a tree comes in on a mechanical tree spade, it may be a 4-inch tree or an 8-inch tree, depending on what the buyer has ordered and purchased. But whichever it is, the same size root ball is coming in with both of them, and that can make a very big difference.

Assume two sizes of trees (large and smaller), both with an X-diameter root ball. The smaller tree is generally going to establish faster and start growing both sooner and faster with a higher prognosis for vitality and appearance. The reason is obvious: The large tree coming in with only a partial root system is going to have to sit in the hole for a time — maybe a couple of years — using available sugar

energy just rebuilding its roots and surviving the seasons before it can start to grow. Its risk of having trouble during that time is elevated, while the small one is likely overtaking it.

Of course, when (time of year) and how planti ng happens are also important factors. But all things being equal again, the idea is to come in with as much root system relative to trunk size as possible.

So if you’re thinking of planting a tree, it may be well to ask your provider about these things. Technically, there is a big difference between surviving and thriving while a common, though not universal, warranty on new trees is one calendar year. After that, it’s yours. Fred Morgan is an ISA-certified arborist and has operated Morgan Tree Service since 1974. He can be contacted at fmorgan@ morgantreeservice.com or 901830-9928.