For the best field study of sprinkler timers, click here. Sometimes called weather-bsed irrigation controllers or ET controllers.

Grass Blocking Spray...

Note the yellowish-green of grass in middle of the lawn. The difference in the health of the grass on different parts of this lawn is caused by uneven watering. This uneven watering is caused by tall grass blocking the spray pattern from the sprinkler heads.

Grass is yellowish green where not enough water reaches the ground

Look closely around the sprinkler head. Notice that grass blades are higher than the spray pattern on the side nearest you. On the spray side of the spray head, notice that the spray is bending other blades of grass. With the grass blocking the spray, more water lands near the head and is not allowed to reached the center of the lawn.

Check for this problem the day before the grass is mowed. After mowing, the problem will not be seen.

Blades of grass blocking spray from sprinkler head


1) Have you gardener first mow the lawn to its normal height.

2) Then turn on the sprinkler system and have your gardener weed-whack around each sprinkler head so that the grass looks like the photos below. Note that grass is cut very low around the sprinkler head.

using a weed-whacker to trim grass around sprinkler heads

When grass is cleared from the spray pattern, then water will reach the center of lawn and be spread more evenly across the lawn. Remember to check for this problem on the day BEFORE mowing.

Blocking sprinkler spray is a very common problem when sprinkler head is near or in planter beds. Plants may need trimming often to allow the sprinkler head to spray on the grass or inside the planter bed. You do NOT want all the sprinkler water to spray only around the sprinkler head. You want the sprinkler water to spray to next sprinkler head. If frequent trimming is required, it may make more sense to remove the bush from the planter head.

For your next sprinkler system, you may want to specify 4" pop-up sprinkler rather the more common 3" pop ups. Then weed whacking around sprinkler heads may not be necessary to achieve good uniformity.