July 4, 2005

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WESLACO – Thinking about planting or transplanting a tree? Forget it - the weather is far too hot. Better to do that between October and February.

Trimming trees is OK, so long as you don't take off too much. But since conditions are so hot and dry in Texas, the best thing for trees is to make sure they're getting enough water.

That's the advice from Paul Johnson, an urban forester with the Texas Forest Service who offices at the Texas A&M Agricultural Research and Extension Center at Weslaco.

"It's been very dry," Johnson said. "Here in South Texas, we're about 7-8 inches behind normal rainfall for the year, so it's very important that we provide trees with the moisture they need to remain healthy."

How much is enough? Johnson said about an inch of water once every week or two is good for most mature trees.

But don't be fooled into thinking a brief rain is an excuse not to water, he said.

"The brief, scattered showers we've been getting provide only minuscule amounts of water, about a tenth of an inch or so," he said. "That's not anywhere near what trees need."

If you're watering your lawn properly, that should be sufficient for any trees growing in the area. The key word being "properly," Johnson said.

"Unfortunately, many homeowners don't know how much water their automatic sprinkler systems are delivering or how to adjust the amount of water it delivers," he said. "It's kind of like VCRs. People just never learn how to program these systems. They tend to leave their sprinkler systems on the settings the installer set them at."

To determine how much water your system delivers, set an empty tuna fish can on your lawn then manually turn on the sprinkler system, he said. However long it takes to fill that can with 1 inch of water is how long your system should run once a week.

"One good, deep soaking of an inch of water per week is best for landscape lawns, plants and trees," Johnson said. "It promotes a larger and deeper root system and you're training your landscape to be drought tolerant."

But a word of caution: Don't abruptly switch from several irrigations per week to only one per week. Wean your yard slowly from frequent watering, Johnson said. If watering every other day, go to a half-inch of water twice weekly for a few weeks before watering only once weekly.

"If it's really, really hot, water twice a week," he said. "And if your lawn slopes, water until it begins to run off. Stop, then restart. Or if you have a high clay content soil that won't hold much water, water a half-inch on two consecutive days."

At his own home, Johnson prefers to use a soaker hose for several hours once a week.

"If you use a 50-foot soaker hose," he said, "you need to run about 100 gallons through it to equal 1 inch of water. It is better to water longer and less often. An hour once a week is better than 15 minutes every day. You can actually have a tree die from drought even though you water it every day."

Finally, Johnson said, do not water at the tree trunk. Water out at the drip line, or the edge of the foliage all around the tree. Let the soaker hose run for several hours to thoroughly soak the soil to a depth of 12-18 inches, he says.

For more information, contact the county Extension agent or call Johnson at (956) 969-5654.