Fairies Ring in Your Yard

If you’ve ever stumbled upon a perfectly round circle of mushrooms in woodland, you’ve probably come across a fairy ring. A fairy ring is simply the living outer edge of mycelium, a network of tiny fungal threads that grows beneath the soil. The fungus feeds on organic matter, such as tree stumps, logs or leaves buried in the ground, and sprouts mushrooms that form a circle around it. The fungus will continue to grow and spread, year after year, until it eventually dies, leaving the mushroom-topped circle of mushrooms above ground.

The phenomenon is so common that it has inspired folklore and myth worldwide. People have seen the circles as dance floors for fairies at night, places where they gather to play games or simply as a sign of good luck.

Whether they show up on golf course putting greens or in home lawns, fairy rings are caused by specific fungi that thrive in wet conditions and soil with high amounts of organic material. The fungi produce compounds that prevent grass from absorbing water from the soil, leading to drought and wilting of the lawn within the ring.

A variety of different fungi can cause fairy rings, but the most commonly observed are those in the family of basidiomycetes. These fungi often take root in wet soil that’s been recently disturbed by tree removal or a flooded area, and can also develop when organic matter accumulates in the ground. Fairy rings can range from a few inches wide to 5 or 10 yards in diameter, and there are three different types of fairy rings that can occur depending on soil type and the fungus involved.

Type 1 fairy rings are the most common in landscapes and occur when a fungus produces compounds that inhibit turfgrass’ ability to absorb moisture, resulting in wilted and brown grass within the ring. Type 2 fairy rings are more common on golf course putting greens, but can also appear in home lawns. These are caused by fungi that decay organic matter more rapidly than normal, causing nitrogen in the soil to increase. Type 3 fairy rings are often seen in lawns in wet regions during the fall.

There are several steps you can take to reduce the incidence of fairy ring in your yard, including routine core aeration to reduce thatch build-up and frequent use of nitrogen fertilizers to green up lawns around the rings. However, to make the biggest impact, you should consider improving your soil’s drainage long-term by adding French drains or other lawn drains, applying compost to clay soils, and creating a rain garden.