Putting an estimate on the dollar value of a shade tree in your landscape is a job best left to certified arborists. They are, after all, the people who work with trees for a living. However, there are some general considerations that form the framework of their calculations, and those are simple enough for even mere mortals to understand. Since fall is the best time to plant new shade trees in your landscape, let's take a look into how trees are compared and evaluated.
The tree's species is a good place to start. Fact is, it's really the only place to start. If you begin with a loser type of a shade tree, it will have no chance of getting any better. Start with junk, and you're destined to end with junk. But, you're probably asking yourself, "What constitutes a superior shade tree? What are the attributes that need to show up on the ledger?" Let's develop a list.
Beauty. This tree is going to be an integral part of your landscape. You can plant a lovely tree species, or you can plant one that is ugly from birth. You might as well go with a good-looking type. Consider its growth form, any seasonal color and its overall texture. It's probably better to have a tree that looks good all 52 weeks of the year, instead of a type that's gorgeous one or two weeks but only tolerable the rest of the time.
Longevity. You want a shade tree that will be with you for decades. This isn't an annual flower garden you're planting. The tree should be the most permanent part of your landscape design. This is where most of the fast-growing shade trees drop down on the list. Their life expectancies are often only 10 to 30 years, and wise gardeners soon decide that that's not acceptable. If you're in doubt, ask your local Texas Certified Nursery Professional how long you can expect a certain tree to live in your landscape. Don't settle for short-timers.
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Site adaptability. Trees that aren't suited to an area's soils and climate get scored down in professional evaluations. As great as they may be in another set of soils or weather, if tree species are eventually going to struggle in your yard, they're worth less in the present. Arborists know to score them down from the outset.
Durability. This bridges somewhat into the two previous considerations, but in this case, we're talking about the species' ability to fend off insects and diseases. Just to use one common example, cotton root rot makes many species less desirable in Texas' alkaline soils. Each of the fast-growing, short-lived tree species has at least one fatal insect or disease invader, and those vulnerabilities greatly lower their estimated values. Certified arborists may look at two tree species of the very same size, yet one will be worth twice what the other tree is, and the reason may be nothing more than the specialists' knowledge that the lesser tree is highly likely to succumb to a serious and predictable problem.
Placement in your landscape. The tree's placement does a lot toward determining its long-term value to its surroundings. If it's positioned in an aesthetically pleasing spot, that adds points to its total. If that pleasing spot also happens to allow it to cast shade on your house on hot summer afternoons, that adds even more value.
Number of trees in your landscape. If you only have one or two shade trees, each tree's estimated dollar value will be greater than if you have six or eight. In fact, at some point, you pass the point of diminishing returns. That's where even the highest-quality shade tree of the best health and vigor will actually diminish the value of your home, simply because you have too many trees.
Condition. This is a critical consideration. If a tree is healthy and vigorous, it's going to be worth a lot more than if it's struggling to hang on. Take photos of your shade trees at their peak late each spring to help prove their condition should any calamity befall them later.
So, you're waiting to see which trees score highest in the professionals' evaluations? For shade trees, the list would usually include live oak, Shumard red oak, chinquapin oak, bur oak, cedar elm, pecan, Chinese pistachio and Southern magnolias. Bald cypress could be added to the group, but only if it's going to be growing in deep, preferably acidic soils that are always moist. For smaller accent trees, the best include Little Gem and Teddy Bear dwarf magnolias, golden raintrees, Lacey oaks, and tree-form yaupon hollies. Redbuds could be added, although they typically have shorter life expectancies than the other species listed.
Neil Sperry publishes Gardens magazine and hosts Texas Gardening noon-1 p.m. Saturdays and 9 a.m.-noon Sundays on WBAP AM/FM. Reach him during those hours at 800-288-9227 or 214-787-1820.