Lawn Sprinkler Gaps

“So, Rocky, what do you see in my sister?”  “Well, Pauley, it’s like this.  I got gaps, she got gaps, but together, we got no gaps.”  Unfortunately, just like two of the actors in the movie Rocky, all lawn sprinkler systems have gaps; gaps in coverage; aka uneven application patterns.


If you ever doubt this, just set out a dozen or so catch cans.  Tuna fish, cat food or water chestnut cans work the best.  Then, run the system for 30 minutes and check to see how much water is in each can.  This simple performance test will show just how far off the efficiency aka evenness of the system is.  If the test shows a quarter inch in one can, and 8 feet away, three fourths of an inch is in the can, then something is wrong and adjustments are necessary.  When the right parts are replaced and adjustments are made, then a dramatic improvement in uniformity can be realized.


The list of possible system flaws is long:

-tree roots growing around a supply line

-sprinkler head not rising up high enough to spray above the grass blades

-sprinkler head not rising up at a 90 degree angle

-sprinkler heads spraying the street or driveway instead of the lawn

-leaking heads and valves

-the spray distance is too short or long

-the system lacks head to head coverage

-grass blades grown over the top of the head

-fences or trees blocking the spray pattern

-and many, many more


You see, lawn sprinkler systems are not really intended to be the primary source of even water application.  That’s delivered by Mother Nature.  Lawn sprinklers are just there to get you by until the next rainfall, which of course, is evenly applied.


So, bottom line, 1. Keep the main purpose of watering in mind – to keep the soil moist, not soggy or dry.  2. Check the soil moisture content weekly with a screwdriver.  If it’s hard to push in the ground, it’s too dry.  If it slides in like a hot knife through butter, it’s too wet.

screwdriver testing moisture content

You can also tell a lot by simply feeling the end of the screwdriver blade after you pull it out of the ground.  If it’s cool and moist with just a tad of moist soil sticking to it, it’s perfect.  If water is dripping off the blade or it’s muddy, it’s too moist; if powdery soil sticks to it, it’s too dry.

screwdriver mud 2

John Fech
Horticulture Extension Educator at Nebraska Extension
John Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of 2 books and over 200 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems and encouraging effective bilingual communication in the green industry. He works extensively with the media to extend the message of landscape sustainability, making over 100 television and radio appearances each year.
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