Washington State University

Plant Clinic FAQs - Lawns

Frequently Asked Questions About Lawns


I am considering putting a new lawn in front of my house and would like recommendations. I also am interested in finding out how to care for an established lawn.
WSU has a bulletin EB0482 "Home Lawns" covering establishment and maintenance of lawns in Washington. You can order the publication from the WSU Bulletins Office.


My newly sodded lawn looked beautiful in the beginning of summer but now dead spots are developing throughout the yard. What am I to do?
SodFirst, how much are you watering your lawn? The Diagnostic Laboratory frequently receives turf samples that have been overwatered. For example, people with a new automatic irrigation system might set it to run daily for 10 to 15 minutes. Not only does this schedule contribute to high water bills, but it probably provides more water than the lawn needs.

The shallow daily watering regime fails to promote development of the roots deep into the underlying soil. In addition, frequent irrigations keep the leaf blades and thatch layer damp, which can promote development of disease problems.

We would require a sample and detailed information on the lawn care to further identify the problem. See lawn sampling instructions for further directions on sampling for lawn problem diagnosis.


Moss is growing all over my lawn. What moss killer can I use to kill it?

MossMoss killers (you can find them at your local hardware, home & garden store, or nursery) can only temporarily get rid of the moss problem- in order to achieve management of the moss problem, you need to address the underlying reasons as to why the turf is not thriving and the moss becomes established (shade, wet conditions...etc.).

Visit the WSU Hortsense web site, and click on "Lawn and Turf" and then click on "Moss", or you can check out the Oregon State University web site on Controlling Moss in Lawns for more information.


We have this unwelcome grass in our yard. The grass seems to die out every summer but then grows again in fall. The grass creeps along and often forms tufts at the top of the plant- it can be very difficult to mow. It feels like you are walking on a padded surface, unlike regular grass. What is it and how can we manage it?
Creeping BentgrassWithout a sample of the grass in question, we are unable to confirm the identity of your problem grass. Your description of walking across the grass suggests one of our native bentgrasses that often grow some distance horizontally before putting out green blades.

Unfortunately there are no "magic bullets" herbicides available for removing one unwanted grass species from the desired types without hurting the wanted turf. So typically to get rid of a weedy grass, we recommend carefully spot spraying a broad spectrum herbicide, for example glyphosate sold under names such as Roundup, on the grasses in the weedy areas.

Follow label directions carefully if herbicides are used. After killing the grasses in this area, you may need to reseed with a desired turf mix to fill in the open spots.

A weedy grass out competing the desired grass species is often an indication of turf management problems. Examples of management problems include growing sunloving species in the shade, over or underwatering, and mowing at the wrong height. For turf management information, see EB0482: Home Lawns.


I need information on craneflies in lawns.

European CraneflyWhatcom County Cooperative Extension has developed an informative website covering craneflies and their management in the Pacific Northwest. View this website at Cranefly Pest of the Pacific Northwest.

As you will read, if you are concerned about cranefly injury to your lawn, you should be monitoring cranefly population within the turf and watching for damage. Additional management recommendations can be found at the WSU Hortsense website by clicking on "Lawn and Turf", and then "European Cranefly".


Moles seem to be taking over my lawn. What can I do about them?
MolehillHaven't you always wanted a "pet" mole? Mole management can be very difficult. Most of the "home remedies", such as juicy fruit gum, mothballs, sonic noisemakers, will not help to remedy the situation. Scissor traps, one of the most effective management strategies against moles, are not currently legal to use in Washington State. For more information on management of moles, refer to these websites: Moles.


After fertilizing our lawn this spring, we noticed that the flowering plum growing in the middle of the lawn developed abnormal looking leaves and twisty branch ends. What is going on?
The plum may have been damaged by application of a growth regulator herbicide. Are you using a lawn fertilizer product that also contains herbicide for weed control (e.g. Weed n Feed)? These mixture products typically contain a hormone mimic herbicide, such as 2,4-D or dicamba. These growth regulator herbicides target broad leaved plants (such as dandelions) but can cause damage to other broadleaf trees and shrubs growing in, or alongside, the lawn. Injury occurs either from drift of the herbicide in the mixture, or from absorption of the herbicide by the tree or shrub roots that are growing beneath the lawn.

Avoid using such herbicides near this tree. Remember that the rooting zone of trees and shrubs typically extends beyond the drip zone of the canopy - the diameter of the root system is typically about 1.5 times the height of the plant. Once the herbicide is out of the environment, the tree should grow normally.

Puyallup Research and Extension Center, 2606 West Pioneer, Puyallup WA 98371-4900, 253-445-4500, Contact Us