"What size landscape tree should I buy from the nursery?" This is an often asked question that I get and is particularly applicable now that many homeowners are establishing trees in their landscape during the spring season.
While patience is a virtue, it is understandable that many homeowners are unwilling to wait for plants to grow to a respectable size. An immediate effect in the landscape is desired, so the biggest plants available are often bought for planting.
But when it comes to planting shade trees, bigger isn't always better even in the great State of Texas. Not only are large trees expensive, they're also heavy and difficult to move around and plant. Once they're planted, they often just sit there for several years, hardly growing.
The reason? Most of the large shade trees are grown by nurserymen in the field or dug up from native areas. The larger the trees' canopies grow, the larger their root systems become. When the trees are dug for sale, much of their root system is left in the ground. For the next several years, these trees oftentimes have to devote their energy to replacing roots, instead of growing new branches.
Medium-size trees, on the other hand, are usually grown in containers. By buying containerized trees, transplant shock can be greatly reduced or even eliminated given proper care. The medium-size trees pick up and start growing soon after planting. Another reason for immediate growth is that they're younger and more vigorous than larger trees.
Selecting medium-size trees results in fewer problems with transplant shock and more vigorous growth; in fact, medium-size trees often catch up in size to larger trees after five-to-six years. This concept applies to almost any species of tree (i.e., Live Oak, Texas Red Oak, Chinese Pistache, etc.).
What constitutes a large versus a medium-size tree? Although there's no hard and fast rule, many nurserymen define a large tree as having a trunk diameter greater than 2 inches, and a medium-size tree as having a trunk diameter between 1 and 2 inches. A large tree can vary from 12 to 20 feet or more in height, while a medium-size tree generally ranges from 8 to 12 feet.
Ultimately, which size tree is right for you depends on your particular needs. If you expect to move shortly, a large tree may enhance your home's marketability. But if you plan to remain in your present home for the foreseeable future, in most cases a medium-size tree is a better option. You will probably be able to plant it yourself, it won't be that long before it attains the size you want and it won't cost you a month's salary.
There are several things you can do to help a medium-size tree grow even faster. In planting trees, dig a planting hole that is at least twice the diameter of the tree's root ball. In fact, research shows that digging the planting hole up to five times the diameter of the root ball is beneficial. Refill the planting hole with the original soil dug out. This may sound harsh if you have gumbo clay soil but if filling the planting hole with improved or high organic matter soil can create a limited soil environment that is so "nice" for the root system that root growth into the surrounding native clay soil may be delayed and, in some cases, roots may never leave the hole you dug.
Also, don't plant the tree too deeply. Do not dig the hole any deeper than the root ball itself as the top of the root ball should protrude above the soil surface a half inch to three-fourths of an inch. Add a three-inch organic mulch (i.e., shredded pine bark) in a three-to-five-foot circular area around the tree to keep down weeds and preserve moisture. Keep the tree well-watered, but not soaked, during dry spells during first two years.
In a few years, you'll have a nice sized tree to beautify the landscape and provide some cool shade during our long hot summers.