On the surface, it seems like a silly question to ask: when should I water my lawn? As East Texas is coming out of an incredibly wet spring and early summer, and landscapes start to dry up, the question is a good one.
Don’t water it at all and you’ll end up with a thinning or dying lawn. Water it too much, or at the wrong time of day, and you will be full of fungal diseases that can also kill your lawn.
Automatic irrigation sprinklers can be of great help and a wonderful tool, if you know how you should use it. Rather than watering on the same schedule each week, adjust your watering schedule according to the weather. And when you decide to irrigate, irrigate deeply. Then wait until the grass begins to show signs of drought stress before watering again.
Symptoms of drought stress include grass leaves turning a dull bluish color, leaf blades rolling or folding, and footprints that remain in the grass after walking across the lawn. To time watering properly, look for the area of the lawn that shows water stress first. Water the entire lawn when that area begins to show symptoms.
A lawn that is watered deeply should generally be able to go a week between waterings. Established lawns with deep, extensive root systems sometimes can be watered even less often. However, if the soil is less than 5 inches deep, irrigation may need to be more frequent.
Early morning is by far the best time to water. Wind and temperatures are usually the lowest of the day, and water pressure is generally good. That allows water to be applied evenly and with little loss from evaporation. Furthermore, watering when the grass is already wet with dew reduces the chance for fungal problems to take hold of vegetation that remains wet far too long.
Watering late in the evening or at night causes leaves to remain wet for an extended period of time, which increases the chance for disease. In fact, if you ever wanted to “cause a fungal disease problem”, just water lightly every afternoon in addition to giving it too much fertilizer!
But when you do irrigate properly, thoroughly wet the soil to a depth of 6 inches with each watering. Shallow watering produces weak, shallow-rooted grass that is more susceptible to drought stress.
So how does a homeowner determine how to wet their soil to a depth of 6 inches? Soil type, sprinkler style, and water pressure determine how much water is needed to wet the soil to that proper depth and how long a sprinkler must run.
Use the following steps to determine how long to run your sprinkler or irrigation system.
First, set five to six open-top cans randomly on the lawn (cans with short sides such as tuna or cat food cans work best). Then turn the sprinkler on for 30 minutes.
Next, measure and record the depth of water caught in each individual can. Then calculate the average depth of water from all the cans. Let us say, as an example, the average for a half hour was half an inch of water.
Now get your shovel, a garden spade, or some soil probe to determine how deeply the soil was wet during the 30-minute time period. The probe will easily push through wet soil but less easily into dry areas.
From the amount of water that was applied in the 30-minute cycle and the depth that it wet the soil, you can then determine how long the sprinkler must run to wet the soil to a depth of 6 inches.
If you have heavy clay, it will be difficult to irrigate 6 inches deep as it may end up running off. Never apply water to the point of run-off. Water that runs off finds its way to storm drains or running down a ditch. This not only wastes a precious resource but spends your money needlessly. If a sprinkler applies water faster than the soil can absorb it, stop irrigating until the surface dries and then resume watering.
Let us not get trapped into thinking one irrigation system is the best. There are many different irrigation systems available. Whether you choose an above ground or underground system, it is important that it is working properly. A routine check should be made to ensure that water is being applied where it is needed, in the amount that it is needed, and in a uniform manner. Use the can method, mentioned earlier, to check the distribution and amount of water being applied, and then make any needed adjustments.
One last pro-tip. Get the longest screwdriver that you can find in your toolbox and use that as your soil probe. Grasping the handle, you can quickly determine how much moisture is in the soil by pushing the head of the screwdriver down into the ground. Moist soil will allow the screwdriver pass readily. Dry soil will be much harder to push through. When neighbors ask what you are doing, reply that you are “fine-tuning” your watering schedule for a healthier lawn!