What are the Dark Green Rings Growing in My Lawn?
After warm nights of heavy rains and high humidly, it is not uncommon to have dark green rings appear in the lawn. Often the outer edge will have large white mushrooms appear in the morning. These dark green rings are commonly referred to as a fairy ring.
The occurrence of these rings is associated with folklore and superstition in nearly every culture where the rings occur. It is the Celtic folklore of the ring that tells tales of fairies dancing – in a circle of course – where we derive the name “Fairy Rings”.
Fairy Rings? The Facts behind the Superstition
Fairy Rings are a community of fungi that are beneficial - they break down organic matter (recycle) into nutrients for the turf. The dark green circle is from an area of nutrient rich soil . The community of fungi usually start from a single point, usually a piece of nutrient rich organic matter buried in the soil. Then the community of fungi radiate outward in a uniform growth rate to form an expanding circle. The rings will continue to grow until the run into a physical barrier. One fairy ring in France is nearly ½ mile in diameter.
Fairy Rings are a Good Thing and Relatively Harmless
The rings are part of God’s creation and master plan. The fungi are recyclers, deriving food from organic matter and recycling dead roots, plant leaves, etc. into usable nutrients for the fungi and higher plant forms. Most of the calls I receive about Fairy Rings are from customers complaining of large white mushrooms or green circles in the lawn. In Pinellas County the fairy rings are a cosmetic problem and rarely cause permanent damage a lawn.
Best Management Practice for Fairy Rings
There is no cure for Fairy Rings – at least not economically. The fungi are soil borne and exist everywhere. The food source is organic matter which is part of the turf eco system. Only in weak, un-irrigated lawns would Fairy Rings “kill” turf. The best management practices for Fairy Ring in St Augustine grass are:
- Keep the soil moisture and nutrient levels medium to medium high
- Frequent mowing maintaining a canopy height of 4” or above.
These two simple management practices will lessen or rid the visual impact of the fairy ring – the green ring and mushrooms. The physical problems are little more difficult to deal with and you may still see weak thin grass in the interior of the Fairy Ring. If the Fairy Ring causes damage, aerating with a pitch fork or spading fork will break up the mycelia mat and allow for the St Augustine to recover. Regardless, the St Augustine should survive or completely recover especially if the soil moisture and fertility levels are kept at medium to medium high. In every instance the Fairy Ring will grow beyond your lawn and out of sight.
FYI: Do not eat the mushrooms. Most of the ones associated with Fairy Rings are considered dangerous and can cause severe intestinal discomfort.