Its Baking - Please Water and Mulch Those Trees
Round Rock Leader
Saturday, August 7, 2004
By Emsud Horozovic, City of Round Rock Forestry Manager
As the temperatures soar toward the three digit mark, I feel it is my obligation as the city’s officially designated tree hugger to remind you to water your trees. I feel for you as you swelter in the heat, though I am currently vacationing in my mother land of Bosnia, where such hot temperatures are illegal.
While in Bosnia, I was thinking how some people should find and visit their roots—and that holds for you, too. Everyone should be covering their roots—their tree roots! As ya’ll (an old Bosnian word for all of you who are baking right now) know, mulch is the most beneficial thing you can apply to your tree. First of all, it is available free to you if you don’t mind hopping over yonder to the Brush Recycling Center. The mulch is available to all water-bill-carrying-residents, licensed as such by the Water Billing Department. The mulch is made up of hardwood trees and brush that was disposed of by the city residents. The mulch is ground fresh daily, just like Starbuck coffee. I’ve written details on this previously, and you can find more information about this on the city web page at www.ci.round-rock.tx.us .
The benefits of mulch are cooling tree roots so they stay moist longer and reducing weeds and grass that compete with the tree for water. As the mulch decomposes, it breaks down into nutritional elements the tree can use. Mulch also keeps your lawn mower and weed eater a safe distance from the trunk. A thin layer of mulch applied as broadly as practical can improve the soil composition, oxygen levels, temperature, and moisture availability where these roots grow. I would not recommend inorganic mulch such as lava rock, stone, shredded rubber, geotextile fabrics and other materials as they do not decompose nor provide any benefits to the tree. Organic mulch is also attractive when applied carefully and watered regularly.
As beneficial as mulch is, too much can be harmful. If trees could talk, they would ask for a blanket of 2-4 inches of organic mulch over their roots, covering the roots under the drip line. Now, let me talk about volcano mulching. Many people, bless their hearts, pile their mulch high against the trunk of their newly planted trees. Mulch applied this way provides a habitat for rodents that could chew on the tree or house insects that can also damage the tree. Also, since mulch retains water, it is not a good idea to apply moisture continually to the bark. Mulch should be located 2-3 inches from the tree bark. Finally, mulch that is applied too thickly does not allow good passage of water and air to the roots.
Once the trees are mulched, and this year’s Texas spring monsoon season have finally stopped, it is time to give some H2O to newly planted trees. Root and shoot growth is slowed down if a tree does not have enough water. Stunted trees may result. It is often difficult for a tree to make up the growth once it has become stunted.
So, what are some of the watering guidelines? Keep the soil moist but not soaked. Over watering will cause leaves to turn yellow or fall off and can drown the tree. Water trees at least once a week at the rate of 10 gallons per caliper inch this time of year. When the soil is dry below the surface of the mulch, it is time to water. If the mulch is moist, do not water. If you have heavy, clay like soil, avoid over watering as the tree may suffocate.
I often see people watering their leaves and tree trunks. There are two problems with this. The first problem is that the tree gets most of its water through the roots, not the leaves and bark! The second problem is that water on the leaves may result in sun damage to the leaves and disease due to insects. Water the ground within the drip line.
A soaker hose is ideal as it can water a greater area at one time and does not need to be moved as often. Also, a soaker hose allows for gentle watering. Blasting water under the drip line may remove nutrients, washing away useful soil. If you have an irrigation system, create separate zones for trees and grass as watering frequency and volume is different among trees, the beloved St. Augustine and other summer color, deer-candy plants. In Central Texas you should continue watering weekly during the winter if there is no rain. Continue watering your newly planted trees for two years in this manner.
You do not generally need to water established trees. However, observe your older trees to see if they need additional water. The need for watering will most likely occur during periods of extended drought. If you do water an older tree, you can either water the entire area under the crown or foliage, or concentrate water on 1/3 of the area.
The best time to water in this blistering heat is between 10 pm and 8 am. Trees relieve water deficits overnight. There is also less evaporation during the late night hours, providing more water in the soil. Finally, pest problems are minimized when watering during the night.
While all of you are adding mulch, watering, and sweltering in the Texas sun and humidity, I’m resting on the Adriatic coast, enjoying the cool breezes. Keep up the good work, and try to catch some vacation time before this summer is over. Enjoy!