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Thursday - August 18, 2011

From: The Woodlands, TX
Region: Southwest
Topic: Compost and Mulch, Watering, Drought Tolerant, Trees
Title: Difficulty of watering at drip line of trees from The Woodlands TX
Answered by: Barbara Medford


I'm watering my couple dozen native mature trees to make sure they survive this drought and its aftermath..and I'm reading about how to water at the drip line. But..all of my trees' drip lines extend over other trees, patios, sidewalks, neighbors' yards, houses, garages, etc. And my property is rumpled with miniature slopes and ridges that send water trickling in all sorts of directions. So should I just soak my entire yard every time I see one tree in the crowd that starts to show yellow leaves? I had been soaking the targeted trunks previously, and that seemed to have been working. What do I do?


So, this is our second chapter of Gardener Survival in a Texas Summer. The first chapter, also for you, is this previous Mr. Smarty Plants question.

Your specific concern this time seems to be concerning mature native trees. We have had several questions about our reference to "drip line." Since roots of large trees will ordinarily go out far beyond the drip line, if you have a lot of trees, yes, you are going to have to cover a lot of ground. Soaking the trunks with water is not what we recommend. Too much moisture on the bark of a tree can invite disease and fungi. Our suggestions to push a hose down in the soil around the tree and let the water drip slowly has to do with young, newly planted trees.

No, we don't think you should soak a yard when one tree shows yellow leaves. Those yellow leaves could be early Fall color because of our extreme drought. We realize some of your trees are under or over other trees, but all of the roots are in the ground, and it's the roots you need to be watering. There is not much you can do about roots under sidewalks, patios and so forth, and some of the roots under foundations or driveways may be causing you problems having nothing to do with where they are being watered. Roots go where they do in search of water and nutrition; if it happens to be under your house, pulling the water out by the tree could be causing settling of your foundation. We always urge people planting trees to stay well away from hardscape of any kind, especially structures.

But you probably had trees on your property, since we know the area in which you live, and you sure want to preserve them if you can. If some of the roots go into your neighbors' yard, some of theirs are probably in your yard. Be responsible neighbors and follow the watering restrictions to water the lawn, gardens and soil under which you know you have tree roots. If you have bare ground, we suggest mulching. That will hold in moisture, help cool the roots and, as it decomposes, add organic material to the soil to aid in drainage and nutrition. Do not pile the mulch up around the trunk-another opportunity for insects and mildew to move in.


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