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Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

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Thursday - December 12, 2013

From: Palm Coast, FL
Region: Southeast
Topic: Pruning, Problem Plants, Trees
Title: Live oaks lifting up sidewalks in Palm Coast FL
Answered by: Barbara Medford

QUESTION:

My live oak trees roots are lifting up my side walks. Can I cut just the roots that are causing the problem without hurting the trees? Thank you.

ANSWER:

Our first impulse was to simply say "NO!" but that would have meant you did not get your money's worth, even though Mr. Smarty Plants is a free service. Frankly, you have a dilemma, and the first question we would ask you is "Which do you care about more, the sidewalk or the oaks?"

Quercus virginiana (Coastal live oak) is the only oak in our Native Plant Database with the common name "live oak"-  it is native to Florida and to Flagler County on the upper east coast of Florida. Other oaks are sometimes dubbed "live oak" but we will use Quercus virginiana (Coastal live oak) for our example.

First, please read this previous Mr. Smarty Plants answer on cutting a live oak's roots. This answer was in response to a question about oak roots interferring with other vegetation, not a sidewalk, but the same principles apply. Another previous question addresses the proximity of oak roots and paving materials.

From the last previous answer:

"Paving should be kept out of the dripline and no closer than 15 feet from the tree trunk. If at all possible, use a porous paving material such as brick with sand joints, open bricks, bark, gravel, etc., which will allow some water penetration and gas exchange. Even with porous paving, the area around the trunk-at least a 10 foot radius-should be natural and uncovered."

Since we live in drought-stricken Central Texas, we would probably vote in favor of losing the sidewalk, but that is going to be expensive and difficult, too, and the process of taking out the sidewalk paving could well result in damage to the tree. We know all this does not help you much, but many, many people read the questions in Ask Mr. Smarty Plants and, if we can't help you, perhaps we will prevent some other gardener from making the same mistake of expecting tree roots and pavement to co-exist. As you can see from the pictures below from our Image Gallery, oak trees can grow to be HUGE and if their root systems grow out to two to three times the circumference of the tree, they are going to go on relentlessly breaking up the sidewalk unless and until you kill the tree and dig out all those roots. We would say the sidewalk is a goner anyway, but only you can make the decision.

 

From the Image Gallery


Coastal live oak
Quercus virginiana

Coastal live oak
Quercus virginiana

Coastal live oak
Quercus virginiana

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