Fairy rings: good to know for preventing and combating fungi in your lawn

Fairy rings are most common in older, nutrient-poor lawns. They thrive on cellulose from woody and plant remnants such as bark, roots, and stump debris. A fairy ring originates from an initial colony whose underground root threads, mycelium, grow outward in an increasingly larger semi or full circle that can exceed 10 metres in diameter but usually remain within a few metres. The fungi themselves grow along the edge of the circle, and inside the fairy ring, vegetation is sometimes stunted and weak, sometimes particularly vigorous depending on the type of fungus.

Why do fairy rings occur?

Fairy rings commonly occur in older lawns, weakened by nutrient deficiency and drought. These are conditions where fungi thrive, and they can quickly colonise large areas. There are several reasons why fairy rings form:

Nutrient deficiency

Fungi compete with grass for nutrients. When fungi establish themselves, they consume the nutrients in the area, making it harder for the grass to thrive. 

Drought

Drought weakens the grass and makes it less resistant. This makes it easier for fungi to establish themselves and spread their mycelium. The mycelium also contributes to drying out the soil, causing the grass to suffer.

Compact soil

Compact soil and poor drainage can contribute to fungi thriving and forming fairy rings.

Preventing fairy rings

There are many things you can do to prevent fairy rings and reduce the risk of them occurring. A well-maintained lawn is more resistant, so the more you take care of your lawn, the greater the chance you will avoid fairy rings.

Fertilise regularly

An easy and sustainable way to fertilise a lawn is to mow it often and let the finely chopped grass clippings remain to become nutrients. The easiest way to do this is to get a robot lawnmower that constantly keeps the lawn short and provides nutrient-rich clippings.

Scarify

A scarifier has blades that go down a couple of centimetres into the lawn and cut the roots. This stimulates growth and produces more side shoots, making the lawn denser. At the same time, the roots get more oxygen, which also stimulates growth and helps the grass absorb water and nutrients more easily, making it stronger and more resistant.

Drain

Ensure your lawn is well-drained: fungi thrive in damp conditions, so if your lawn has poor drainage and water often stands after rain or snowmelt, the risk of fairy rings increases.

How to get rid of a fairy ring

Getting rid of fairy rings can be tricky, but the main rule is that the more you strengthen the grass's power and resistance, the harder it is for the fairy rings to survive.

Regularly clean up

Ensure you regularly clean up dead leaves and other cellulose-rich organic material from the lawn. This reduces the risk of creating an environment where fungi thrive.

Water properly

Preventing the lawn from drying out can help prevent a fairy circle from spreading. However, fungi thrive in moisture, so it is better to water thoroughly and infrequently rather than often and superficially. The key is to keep the lawn neither too dry nor too damp.

Fertilise correctly

By adding nutrients to the lawn, you can strengthen the grass's resistance and reduce the fungi's competitive advantage. Use a balanced fertiliser that contains nitrogen, phosphorus, and potassium. Chicken manure is rich in nitrogen and beneficial. Avoid dressing the grass with cellulose-rich material such as bark mulch, as it promotes fungal growth.

Aerate

Aerate the grassroots with a scarifier. When you aerate the lawn, the roots get more oxygen, which helps it grow better. At the same time, you improve soil drainage so that water and nutrients penetrate more easily to the roots.

Lime the lawn

Liming raises the pH value of the soil, making it less hospitable for fungus in lawns. A fairy ring prefers acidic environments, and lime makes the soil less acidic, inhibiting fungal growth.

Fairy rings can be persistent and challenging to eliminate, but with the right knowledge and methods, you can both prevent and combat them. The best protection against fairy rings is a strong and healthy lawn, so it's worth taking good care of it.