The Garden Guru: What not to do when it comes to trees

The next time you’re in a tall building looking out over Fort Worth, take a gander at that vast urban forest. There are places where you can look for miles and hardly see rooftops — the trees are growing branch-against-branch.

And Fort Worth isn’t alone. If you’re ever way out in the Davis Mountains in Alpine, visit the campus of Sul Ross State University and look down into the city. Even in that arid West Texas environment, there are thousands of trees.

Texans love trees. They beautify, and they cool. They slow the north winds, and they provide drama and accent to our surroundings. Trees are good to us. But, sadly, we’re not always good to our trees.

Things we shouldn’t do when it comes to trees:

Plant the wrong species for our soils and climate. Fast growth, for example, is a terrible criterion for choosing a shade tree. They suffer short and hard lives and are prone to insect, disease and storm damage.

Or, we choose trees that can’t handle our heavy, alkaline soils. East Texas pines, water oaks and even dogwoods fall into this group.

You simply can’t do enough soil amending to satisfy trees as their root systems grow farther and wider.

Plant trees whose mature size doesn’t match up with our needs. A prime example is trees that have to be flat-sided or topped so that they can fit around power lines.

Ask your local nursery how tall and wide your tree will grow. Read and check resources online to get more opinions. Keeping trees out of utilities is our responsibility, not one we should leave to the linemen.

Start with trees that are too large to transplant successfully. This is when an eager owner of a new home envisions "instant shade" and buys the biggest tree possible. If it’s a tall sapling that’s been plucked off a hillside, then wrapped in burlap, it probably will suffer from the loss of roots during the transplanting.

A smaller, nursery-grown tree that has proportionately more of its roots intact will generally take off much faster. Container-grown trees establish most quickly.

Improperly nurture young trees. Perhaps you drive home with the new tree hanging out of the back of your car or pickup. Maybe you didn’t get it planted right away and it ran out of steam waiting in its original pot. Or, perhaps you planted it punctually but forgot to water it on one or more critical occasions.

New trees will dry out more quickly than the adjacent soil, so hand-watering is a critical issue for the first 12 to 18 months of that tree’s life in your landscape.

Cover a tree’s root system with fill. Gardeners are often amazed to find that 90 percent of any root system is in the top foot of soil. And if you cover the majority of the tree’s roots with fill soil — even a couple of inches — you can do permanent harm. It usually takes a year or two, but the tree will lose the battle, and you may not even know the reason.

Strip bark with line trimmers and mower wheels. This is the surest way to kill a tree because of the configuration of the plant tissues in that trunk.

The bark is the protective covering, and just inside the bark is the phloem. It’s the cylinder of tissue that conducts manufactured sugars from the leaves down to the roots.

Cutting through the phloem, the cambium and perhaps even into the xylem is another way to do major damage. Protect the trunk at all costs.

Blame trees when our house foundations and concrete driveways fail. Granted, trees suck a lot of moisture out of the soil. If the roots extend beneath a house, that could contribute to foundation failure. However, there is an option short of removing the tree.

Cut a trench between the trunk and the house and install a root-barrier fabric to prevent root growth where it’s not wanted.

Texas has been blessed by the urban foresters of the Texas Forest Service as well as a cadre of trained and skilled arborists. Let’s follow their lead and take care of our shade trees.