Fairy rings are a relatively common phenomenon in lawns. They typically appear as circular rings in the turf, where the grass around the perimeter is darker green and often more vigorous than the surrounding lawn.

The diameter of these rings can vary widely from one lawn to another. In some cases, they may measure only a few centimeters, while in others they can expand to several meters in diameter.

Fairy rings are caused by naturally occurring soil fungi. These fungi grow outward in a circular pattern and feed on organic matter present in the soil, such as:

• accumulated thatch in the lawn;
• decaying tree roots;
• old tree stumps or buried wood;
• other organic materials in the soil.

As these fungi break down organic matter, they release nutrients—particularly nitrogen—which are absorbed by the grass roots. This explains why the grass in the ring becomes greener and more vigorous.

When the soil contains large amounts of organic matter, fairy rings may persist for several years, as the fungi continue to grow and expand in the soil.

Several lawn care practices can help reduce the appearance or persistence of fairy rings:

• remove old tree stumps and roots when possible;
• reduce excessive thatch buildup in the lawn;
• aerate the soil regularly to promote organic matter decomposition;
• perform a soil analysis to better understand soil conditions;
• adjust soil pH if necessary;
• avoid excessive nitrogen fertilization, which can intensify the color differences.

With proper lawn care and soil management, it is often possible to reduce the visibility of fairy rings and improve overall lawn uniformity.