During a normal year we will experience at least three to four weeks of drought conditions. Typically, this happens during the months of July and August. This year has been the exception. We have been experiencing dry conditions since mid-May in many areas. Many folks continue to worry about trees and shrubs when it comes to our lack of rainfall.
Prolonged droughts affect young and mature trees and shrubs. The main point to clarify is for how long trees and shrubs are affected and what is the result of a drought. Some trees and shrubs we can see immediate symptoms of leaf drop, leaves drooping or sunscald on the leaves. Other symptoms depend on the type of tree or shrub. Some will show dieback on a few stems or branches while others may completely die. Depending on the plant, symptoms can appear at different times. Some symptoms may appear within days and some may take months or even years. For example, the drought of 2010/2011 had a major impact on pine trees. We are still losing pines from that drought. Basically, stressful events can decrease the lifespan of a tree and also make it more susceptible to other issues like diseases and insects. It is important for us to take care of the ones that we have the ability to impact. So what can we do?
There are things you can do to minimize the effects of drought. Trees and shrubs benefit from slow deep watering that is less frequent than what our turfgrass needs. Water long and slowly will allow water to soak deep into the soil. One way to check and see if you are watering enough is to use a screwdriver and simply try to push it into the ground. If it is dry, it will not be able to go into the ground. If the ground is moist enough, you will be able to get it to go at least 6 to 8 inches into the ground. Watering will vary depending on whether the trees are young or mature. Just a few extra tidbits. It is important to minimize water contact with the trunk and lower leaves water droplets can increase problems with bacteria and other harmful diseases. Also, it is important to understand your soil. A sandy soil may require more frequent irrigation to remain moist, whereas as clay type soil can hold moisture for longer periods of time but require a much slower application of water.
Mature Trees
Mature trees should be watered at least every two weeks during drought. Water should be applied to the entire area within the dripline under the crown of the tree. During periods of prolonged drought, apply water under the canopy while keeping any local water restrictions n mind.
Younger Trees & Shrubs
Younger trees and shrubs will require more frequent irrigation until they become established at roughly two -five years after planting. (very plant dependent) It is recommended to water newly planted trees 2-3 times a week with at least one gallon of water per caliper inch of trunk diameter. Watering should be focused in close proximity to the original root ball until roots develop further out. Water should be applied slowly allowing it to soak deep into the soil rather than run off. Typically, newly planted trees and shrubs have soil that forms a “crater” or “bowl” just beyond the root ball. This area can be used to fill up with water and allow it to percolate directly where it is needed.
Lastly, another way to assist trees during times of drought is utilizing mulch. Hardwood mulch is beneficial to conserving a tree’s water and retaining moisture in the soil. Mulch helps to improve water percolation into the soil and keeps that root system underneath cooler than surrounding areas. This reduces water lost to evaporation and provides the tree with less stress for any water or nutrient exchange. Mulch also reduces competition from other weeds and generally improves overall tree health. Mulch should be applied no more than three inches thick over as much of the root system as possible, but not in direct contact with the tree trunk.
Don’t forget to send your garden questions to Plant Answers at 9020 Airport Rd., Conroe TX 77303 or e-mail me at
mpotter@ag.tamu.edu.
