Moss in lawn

Asked July 15, 2020, 7:34 PM EDT

I've seen articles online saying that a mixture of dish soap and water is an effective way to kill moss, but then I've seen other articles that say its a myth. Im not really wanting to use pesticides or harsh chemicals that may harm the environment or the grass itself. What is the best and most effective way to get moss out of a lawn?

Multnomah County Oregon

1 Response

Moss in the lawn is very annoying. Unfortunately, our mild wet winters favor moss growth. To really get rid of moss your lawn grasses have to be more vigorous than the moss. Mosses like moist, shady conditions. They tolerate compacted soil because they have only very shallow attachments that don't penetrate very far into the soil. Grasses require well-drained soil so the roots can get water and air.. Grasses also require sun, at least 4 hours of direct sun per day. Soil pH should be between 6-6.5. If your lawn soil is pH 5 or less you need to add lime to adjust the pH. You can buy pH test kits at your local garden center, or take a sample to a lab for analysis. There are several labs who perform soil analyses, but this lab has offices in Portland, A&L Laboratories http://www.al-labs-west.com/contact-oregon.php.

Watering is very important for a healthy lawn. A 3-time/week schedule of 1/4-1/3" water delivered each time is recommended. This schedule makes moisture available to the grass roots without overwatering, which encourages mosses. Regular mowing at 2-3 inches mowing height is also recommended. High nitrogen fertilizer applied in the spring and in the fall keep lawn growing well.

If your lawn has areas of soil compaction you may need to aerate the soil. A soil aerater pulls cores from the soil, which loosens it and allows water and air to penetrate the soil.

Dish detergent has a surfactant action, which probably interferes with membrane function. You can also remove moss by dethatching your lawn. Dethatching loosens the moss. Rake the moss fragments afterward to remove them. If you want to remove moss chemically, the safest and most effective treatments are sulfate products. Ferrous sulfate, iron sulfate or aluminum sulfate all work well. They are readily available from your garden center. Once the moss is gone reseed the bare spots and reseed any thin spots.

This article by Dr. Kowolski, the lawn specialist at OSU is an excellent overview of moss control in our lawns, If you Mind Moss, Get on Board with Preventative Measures https://extension.oregonstate.edu/news/if-you-mind-moss-get-board-preventative-measures.