Drip Irrigation Keeps Trees Looking and Feeling their Best
July 20, 2015
The sudden intense summer heat has taken many of us by surprise, given our extended cool rainy spring. It seemed like the rain and flooding would never end, and we wouldn’t have to water our trees all summer. But oh how quickly things change here in the Dallas & Fort Worth area. The rain has completely stopped and temperatures have heated up above 100 F degrees. All of a sudden, plants are becoming a bit stressed for water.
How NOT to water your tree.
We are often asked “do we really need to water our trees as regularly as the rest of our landscape?” It of course depends on the type of tree, it’s age and the weather. Most established landscape trees and plants do well with the equivalent of 1” of rainfall per week. So this is what you should try to deliver if it’s not raining.
You might think that most trees have a tap root that grows deep into the soil in search of moisture. Did you know that most of a tree’s feeder root system is in the top 18-inches of soil? This wide network of roots both stabilize the tree and take up water and nutrients. That also means your trees don’t have an ever-present supply deep down of groundwater.
When trees become drought stressed they can become a hazard. Branches become weak and so does the structural root system. A drought-stressed brittle tree is much more likely to split, lose branches or fall over during a storm or high winds. Urban trees are very important to keeping urban temperatures down, improving air quality and reducing flooding and runoff. So it is important to go ahead and provide some supplemental water to our trees during times of dry heat.
Best watering practices
If you have an automatic irrigation system that sprays water into the air, your trees might not be getting enough moisture. If that tree is also competing with surrounding lawn or groundcover, then neither may be getting what they need. Drip irrigation can be an effective and efficient way to get your tree the water it needs during the hottest part of the summer. Drip irrigation can reduce water evaporation and runoff from 50%-70%. You can install an automated drip irrigation system, or simply attach a soaker hose to your outdoor spigot and run it around the base of your tree.
Drip lines deliver water directly and efficiently to the tree’s feeder roots. Note how the lawn is not allowed to grow up against the trunk, and the root flare is visible. Drip hoses can be covered with mulch, as long as the mulch is not piled up against the tree trunk.
Also notice the areas between the two trees where the lawn is thinning? Warm season lawns don’t thrive in shady conditions.
Tree vs Your Lawn
As you might already know, grass and large shade trees don’t play nice. Not only does the tree starve the lawn of much-needed sunlight, but also water and nutrients. It’s best to designate the area right under your tree’s canopy a “grass-free zone”. Leave the root flare properly exposed and then cover bare soil with mulch to retain moisture.
When watering your trees and landscape, be sure you know your city’s watering guidelines. We posted them in a previous post HERE.