Q. Last fall, my lawn was looking terrible. It had some random brown areas that ended up being overtaken by weeds. Now that spring is coming, I want to fix the grass, but I don’t know where to start.
When the lawn is looking bad, it may be tempting to look for something to kill – fungus, grubs, burrowing animals – but the most likely source of the problem is your irrigation system.
Although a well-designed and properly installed irrigation system should be relatively low maintenance, it is not maintenance-free. Possible ground settling and shifting, tree roots, and thatch build-up can affect in-ground irrigation systems.
Brown spots, weedy spots, soggy areas, and excessive water on the sidewalk or driveway are all signs of an irrigation system that may need attention.
If you see any of these signs, first carefully observe your irrigation system as it runs through a full cycle. Sometimes the problem may be as simple as an error in programming: Did the sprinklers run in all zones? Did they run for the desired amount of time? If some zones are not running, but the controller says that they are, there may be a malfunctioning valve or dislodged wire. If there’s a soggy area in the zone where the sprinklers should be running, there may be a fractured pipe.
If you have pop-up sprinkler heads, look carefully and check that each head is actually popping up, and that it’s popping up to its full height. Sometimes ground settling around a sprinkler will block the water flow. Built-up thatch can prevent a sprinkler from popping up or popping up to its full height. In this case, simply cutting the thatch away from the sprinkler head can solve the problem.
Sprinkler systems should provide head-to-head coverage. This means that the spray from one sprinkler should reach all the adjacent sprinkler heads. Head-to-head coverage will ideally give even coverage throughout the area being irrigated. This can’t always be confirmed by just watching the system run. To test for even coverage, place empty cat food or tuna cans evenly spaced all over the lawn and run the system. After the cycle has finished, there should be an equal amount of water in each can, no matter how far it is from a sprinkler head.
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If the tuna can test shows that there’s uneven coverage, even if every sprinkler head appears to be working, one or more sprinkler head may be improperly aimed or partially blocked. If you suspect blockage, remove the sprinkler and flush the system. Ants, dirt, or other materials may have entered the system and this should remove them. Excessive water hitting the sidewalk or driveway indicates that one or more heads may simply be misaimed. This is easily fixed by gently turning the head back to where it’s supposed to be.
If you need to replace more than a few sprinkler heads, consider the newer MP rotator sprinklers. These sprinklers spray in a rotating stream pattern. They are less likely to become clogged, and there is less water loss due to evaporation because the water comes out in streams instead of a fine spray or mist.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu