Most of us cringe when asked how much and how often we should water our lawns. Well, cringe no more!
There is a very simple way to determine how long to run our lawn irrigation, and a simpler way to determine how often to run it! Better yet, once you determine the “magic number”, you will not have to do it again! (I know that most people pick a “magic number” out of the sky to determine how long your sprinkler will run.)
No more guesswork! Each lawn has different soils and different irrigation systems. We cannot treat them all the same!
The method I am going to describe is called an “Irrigation Audit”. It is often used when lawns have dry patches that cannot be explained by insects or disease. Here is how it is done:
*Place several cans or cups (that will not tip over) in several places in your lawn. If you have dry patches, place some there, and place some in the green areas as well.
*Run your irrigation on the normal day and time that you are used to watering, for the normal length of time.
*Make a map of your yard and mark where the cups are. Write the amount of water collected in each cup next to each mark.
*Compare the results. This will tell you if your irrigation is reaching each area equally. If not, it is time to make some adjustments! This could also explain those dry, brown areas!
*Next, using a shovel or a trowel, dig down next to each cup to see how far the water has percolated. Different soils percolate at different rates, and each sprinkler system delivers varying amounts of water. So, this information will be quite useful when determining how long to run your irrigation. Your goal is to have the water percolate 6” deep. (I am hoping and assuming that you have 6” of soil under your lawn!)
*Calculate how long your irrigation system would need to run to wet the ground to a depth of 6”. If you watered for 20 minutes and collected ½” of water that percolated 3”, you could estimate that the irrigation would need to run for 40 minutes to collect 1” of water and percolate 6”. (This is just an example. Each situation will be unique.) Test your new estimated irrigation time on your next watering cycle to confirm. Make adjustments if needed. You now have a “tested” run-time for your sprinklers!
*Now, how often should you water your lawn? In a perfect world, without watering restrictions, you would use the powers of observation to determine when to water your lawn. Research has shown that lawns develop deeper, healthier root systems when allowed to reach their “threshold” or stress point. In St. Augustine grass, this is seen as the leaf blades folding lengthwise. This is the point at which St. Augustine should be watered to a depth of 6”. Bermuda grass has reached its stress point when a footprint will not “bounce back”, and remains indented in the lawn! Again, water the lawn to a depth of 6” at this time.
*With water restrictions in place, it becomes even more important to water efficiently and deeply when we do water. With a deeper root system, your lawn will have a better chance of surviving drought and the cold in winter. As you can imagine, frequent, shallow watering of lawns makes for shallow root systems. Shallow root systems will not tolerate drought or cold, and are more susceptible to weed infestation.