Watering trees during the summer can be tricky. To avoid underwatering or overwatering, you need an irrigation plan that takes into consideration several key aspects, including the size of your trees, the soil that they’re planted in, and changing moisture levels.
During the summer in North Texas, a tree should be watered one day a week for 30-40 minutes total, without runoff. One to 1 1/2 inches in volume. If there has been a recent heavy rainfall, adjustments should be made accordingly.
Summer Irrigation Plan
When establishing a summer irrigation plan for your trees, several factors need to be considered. Tree size, tree species, soil type, soil conditions, and weather, just to name a few.
In addition to doing your own research, we highly recommend that you consult with an arborist certified by the International Society of Arboriculture. Fine-tuning your irrigation system can help eliminate any excess watering. Which means lower water bills!
An irrigation plan for your trees should include: when to water, where to water, and how often and how much to water.
When to Water
Contrary to popular belief, you will not burn your plants if you water them in the middle of the day. Many prestigious golf courses water during hours of intense sunlight to cool the greens.
We recommend that you water during the evening or early morning hours. This will ensure that the maximum amount of moisture reaches the roots of your tree. Cooler temperatures and lack of sunlight reduce the rate of evaporation.
Soil Moisture Levels
Soil moisture levels are also an important consideration when determining when to water. You should not water if the ground is too moist. Besides being wasteful, excessive soil moisture can lead to disease and root problems. If the ground is saturated from a recent rainfall or from accidental overwatering, we recommend that you wait until the ground is dry before you water.
Ideal moisture levels will depend on soil type. For example, clay retains moisture better than sandy soils. For more information on soil in Denton county, we recommend contacting Earth Kind Services.)
Testing Soil Moisture Levels
The least expensive way is to test soil moisture level is to stick a long screwdriver into the ground. If the soil is moist, the screwdriver will go in easily. If you experience some resistance, the soil is dry.
A more accurate means of testing soil moisture is to use a moisture meter. Moisture meters can be purchased online or at your local hardware store.
Where to Water
In order to thrive, trees need to be watered within the root zone where their feeder roots are located.
The feeder roots of a mature tree are concentrated in the outer 1/3 of the area covered by the tree’s canopy and extends a few feet beyond the tree’s drip line.
For newly planted trees, soak the root ball and the soil around the root ball out a few feet. This will encourage root development.
How Much to Water and How Often
During the summer in North Texas, we recommend 1 to 1 1/2 inches of water per week. If there has been a heavy rainfall, then you will need to adjust that accordingly.
Overwatering your trees is a serious problem. And it occurs more often than you might think. Overwatering can cause damage to the roots and lead to disease. Be sure to check the soil’s moisture level after a substantial amount of rain. (See above for more on testing moisture levels.)
Automatic Sprinkler Systems
Automatic sprinkler systems are the most popular way to ensure that your trees get the water they need. To ensure that your sprinkler system is dispersing 1 to 1 1/2 inches of water per week, you will need test it.
To test if your sprinkler system is reaching your tree?s root zones, run the following test:
1. Place an empty 5 oz. tuna can within your tree’s root zone.
2. Run your sprinkler system for 15 minutes.
3. Check the amount of water in the tuna can.
Use the amount of water in the can to gauge how long your sprinkler system should be set to adequately cover each zone.
Setting Your Sprinkler System
If your sprinkler system is set to run two times per week,we recommend the following schedule:
Each zone 3 times for 7 to 8 minutes on each watering day.
If you can only run your sprinkler system once per week, we would suggest this schedule:
Each zone 3 times for 12 to 15 minutes on the watering day.
Watering three times on a given day will reduce run-off and ensure that the soil is able to absorb the water adequately.
To see a demonstration:
If you notice any problems with your tree, before or after you have set up your sprinkler system, we recommend consulting a certified arborist and an irrigation specialist. Overwatering or underwatering could be occurring.
If you don’t have a sprinkler system in place, the next best form of irrigation is good old-fashioned hand watering. Hand watering your tree’s roots can be time consuming, but if done properly, it can get needed water to your tree’s feeder roots just as well as a sprinkler system. Consistency is key!
Soaker Hoses and Drip Irrigation
Soaker hoses and drip irrigation allow the water to be slowly absorbed into the ground, eliminating wasteful runoff. This method works well for newly planted trees, which need water at the root ball. More mature trees might not enough water using this method. Please consult with a certified arborist if you have any questions.
Mulch, the Moisture Sealant
During the hot summer months, moisture retention is especially important. Mulch conserves and protects, keeping the soil underneath moist longer.
We recommend placing mulch away from the trunk, approximately 18 inches at minimum, covering the ground under the limbs. The mulch should be no more than 2 inches thick. Keep root flares exposed to the air. They must remain exposed for the tree to thrive. (For more on root flares, check out “Are Your Trees Planted Too Deep?”)
Establishing a summer irrigation plan is important to the health and vitality of your trees. Consulting with a certified arborist and an irrigation specialist to set up a plan will help you to keep your trees and the surrounding vegetation thriving, despite the dry, hot summer weather.