Safelawns Daily Post and Q&A Blog

Fairy rings drive some lawn owners crazy. (University of Minnesota photo)

Mother Nature rarely offers up a mystery any more intriguing than the phenomenon known as fairy ring. One can only imagine what our ancestors must have conjured up as the reason for giant circles that seem to appear from nowhere in the middle of stands of grass in the summer.

At a recent consulting job in Maryland, the groundskeepers were perplexed about whether or not to take action. Their rings were more half moons, that presented as about a 20-foot arc of dark green grass. At another area of the property, the fairy rings appeared as a giant, almost perfect, circle of mushrooms.

In some cases fairy rings can be quite unsightly, but in most cases they’re a minor nuisance. In virtually all cases, the best advice is to leave well enough alone. They will eventually grow out and die off.

WHAT ARE THEY?

Fairy rings are a result of Saprophytic fungi that degrade organic matter, most often accumulated thatch, in lawns that have been treated with excessive fertilizers in an irrigated lawn. As the fungi grow in an outward direction, the leading edge of the fungi produces dark green grass because of all the nutrients that are being consumed and released by the fungi. That dark green color produces the visible fairy ring that, through the years, can become quite large.

One interesting note to me is that the mere existence of fairy rings is advertisement number one for how microscopic organisms like fungi process nutrients and allow grass to grow dark and green. All we’re doing in organic lawn care is trying to enhance that process. The only reason fairy rings are even a problem for some folks is that the fungi are working TOO well and therefore creating an unbalanced appearance in some areas of the lawn.

But I digress.

Some people have the urge to dig out the soil in the area of the fairy ring and start over. But with all the time and effort that would take — not to mention how bad the area would look before the new grass took hold and blended in with the existing lawn — you should avoid that urge. Fungicides rarely work, either, and the chemical ones are toxic as heck.

In general, don’t overwater and overfertilize your lawn and you won’t have a problem. If fairy rings do appear, aerate the ring to allow water to penetrate the heavy fungal layer. You can also apply a surfactant (or wetting agent) to the area to increase water flow. Here’s a link to a good one: http://www.poulengerusa.com/ called SeaSafe. Allow the grass to grow tall during the appearance of the fairy ring to mask it from the surrounding area.

If you do get a fairy ring in a lawn that is otherwise pale green, one strategy is to take a soil test of the surrounding area so that you can fertilize and adjust the pH as necessary to maximize the green color of the overall lawn. That, too, will mask the fairy ring problem.

One final note about the mushrooms that accompany fairy ring: if you have children, rake up the mushrooms. As a father of a 1-year-old, I know how everything winds up in her mouth. Unless your an expert on edible fungi, then ASSUME the mushrooms are poisonous and get rid of them.

Here’s a good fact sheet from Cornell on fairy ring: http://plantclinic.cornell.edu/FactSheets/fairyring/fairyring.htm.