Some people love moss; others consider it an invader.
Golf course managers, for instance, consider moss an infestation that ruins playing surface for their customers. No surprise, then, that a golf course manager's search for a grass-safe moss killer resulted in today's best known do-it-yourself approach: dish soap.
An article in the June 1998 edition of Golf Course Management was titled "Dawn Takes Moss Out of Your Way." It tells the story of an Ohio golf course manager's observation that Ultra Dawn dish soap reduced moss without harming grass.
Many people today, including some golf course turf managers, use a solution of four ounces dish soap mixed with one gallon of water. But is it a good idea?
Moss Removal Myths
A University of Arkansas study, "Moss Control in Creeping Bentgrass Putting Greens," casts doubt on the dish soap approach. The authors report that dish soap had almost no effect in their Springdale, AR, trial. Their literature review revealed that, in other places, dish soap required numerous applications and had variable effects. Dish soap seemed to be more effective in some climates than others. Furthermore, dish soap can produce unacceptable turf damage under some circumstances.
Bottom line: The idea that dish soap will permanently remove moss from a lawn is probably a myth.
What about commercial moss killers designed for use on lawns? While many commercial preparations kill moss, some of those preparations also harm lawns and gardens. The authors of the University of Arkansas study say the commercial moss removal products they used successfully in their study had variable performance in other academic studies.
Some of those commercial products are based on potassium salts of fatty acids, a.k.a. soaps. Scotts 3-in-1 Moss Control is one example. Moss Aside from Neudorf is another. In both cases, the product labels claim the products are safe on lawns and that only one or two applications are needed to reduce moss for up to one year.
Bottom line: Commercial formulas may be worth an experiment if the moss in your lawn (or your golf course) is intolerable. The best advice is to start small and observe the effects.
Practical Approaches to Moss Reduction
Many books and articles point out that moss goes away when we change the characteristics of the location. But even here, myths are present.
"Many people think that moss removal is a simple question of adjusting pH," according to C.L. Fornari, horticulturist, and author of the popular myth-busting garden book "Coffee for Roses" (St. Lynn's Press, 2014). The pervasive belief is that lime applications will reduce moss.
"The truth is that moss is happy to grow on alkaline, acidic, or neutral soil," she says. "Changing the pH alone isn't enough to kill moss."
Moss thrives on a compact ground, in the shade, and in the presence of steady moisture.
"Any one of these conditions is enough for moss to flourish," says Fornari. "So if the soil is compact and hasn't enough organic matter or the lawn hasn't been aerated in two or more years, moss will love it there. Moss loves to spread in perennial gardens that haven't been mulched because soil without mulch is usually compact."
Fornari points out that watering regimens--in addition to local rainfall--may be a key factor.
"Watering deeply but less often is the best way to irrigate all plants except moss," she says. "If you're watering for 15 to 20 minutes every day or every other day, moss will be your new best friend. Other plants, however, will develop shallow roots, leaf spot or crown rot."
In fact, professional moss growers prescribe short, frequent watering when you want to encourage moss.
One practical, non-chemical approach that appears in some literature is to "rough up" the moss, rake it away, and spread a thin layer of sand on the area. Sand can desiccate moss. Moss has no vascular system, unlike most other plants, so it gets moisture through cell walls.
On the other hand, you may want to embrace the moss and remove the grass. "Right plant for the place" is an excellent motto to guide all our landscape decisions.