Questions about tree roots: June 24, 2021

Roots are slightly important to our shade trees. Just a little! They supply all of their water and nutrients. And they keep them erect. We need to do all we can to nurture healthy root systems.

But sometimes roots can become troublesome. Like these two fairly typical questions I’ve been asked recently.

“What can I do about bald cypress knees? We had no idea they would be such a problem when we planted our tree years ago.”

Those “knees” that extend out into the air are normal developments of bald cypress trees. When they grow in swampy areas those become breathing structures for the root system. Some specimens seem to be more likely to produce them than others, even under identical situations.

You can certainly remove them with a sharp, long-handled axe. (Be careful!) An arborist can determine if they are heading toward your foundation. If the trees are fairly close to the house it’s quite likely that they will be going that way, because soil beneath slabs is consistently cool and moist. Those knees have incredible power capable of doing great damage if left in place beneath concrete.

If you don’t have a certified arborist on call already, a local independent retail garden center would be able to refer you to one.

“Is an oak tree 15 feet from our foundation too close? We have a tree that’s 20 inches in diameter. It has a 3-inch root heading toward the house.”

If you have an oak tree of that size only 15 feet from your house, this probably is not the largest root heading toward your foundation. It’s just the one that’s most visible to you at the moment. Indeed, it would be a good idea to have a certified arborist look at the situation and assess what might need to be done, even to do a little exploratory digging to examine other roots.

If any roots are to be cut, it should be done in the fall, after the stress of the hot, dry weather has passed. Discuss the possibility of installing a root barrier and whether the arborist feels it would offer any help.