I am often asked on a radio show I co present (The Great Outdoors on BBC Radio Humberside) about fairy rings in lawns, in particular what is the best way that the home gardener can eradicate them.
In the old days there used to be some very effective chemicals, including Armillatox. This has now been reformulated and in the UK is sold as a soap based cleaner. Other products have been banned or simply not had their licenses renewed.
My advice therefore always starts with the claim that the only 100% sure fire way to eradicate a fairy ring is to bring in an excavator and remove the ring and the surrounding top soil, and then import new top soil, firm, level and sow a new lawn.
For some reason many people seem to find this a little bit extreme.
I therefore recommend that instead the fairy ring is first examined to understand it.
The inner and outer tufts of grass in the ring are lush and green as the fungus in the fairy ring is breaking down dead organic material in the soil and so releasing nutrients. The inner portion of the ring often has brown and dead grass in it. This grass has been killed by drought as the fungus growing in the soil is so dense it does not allow rain to soak into the soil.
The best control is to use a garden fork, and insert the tines to their full depth in the dead grass, give a wiggle to open the tine holes up and then move back a few inches and repeat the process until the whole ring is forked to allow the rain to get into the area and so rejuvenate the grass.
Gordon Duncan, who is the Managing Partner of Green Thumb in Beverley recently contacted me to discuss the matter, in his email he suggests….
“Last Sunday on your radio programme you gave advice to a customer who had fairy rings on their lawn. You are quite right that the only certain way to remove it is to get an excavator! You are also right to say the most effective long term control of using chemicals has been banned.
“However, over the last 15 years in the Hull and East Yorkshire area we have been reasonably successful at dealing with these problems.
“Our method is to hollow-tine the affected area and at least 12” beyond the visible extremity of the darker grass at the edge of the ring. We then remove the cores, water the ground and then apply both specialist wetting agents and a fungicidal treatment. (Both these products are not available to the general public). We then follow up with further watering. We also ask the customer to water regularly, once a week, if it does not rain to ensure the ground remains moist.
“This procedure has proved successful and in some cases it has been several years before any sign of any return and we see no variation in results regardless of the three types of fairy ring. In a very small number of cases we have seen some return of the fairy ring after several months. In those situations we repeat the process free of charge, but this is usually where there has been a severe infection.
“You also said that in one or two years the fairy ring is likely to have moved from the lawn into the borders. Our experience is that the fairy ring does move regularly, but slowly, and it will only leave the lawn completely in 2 years, if the infection is only a few inches from the edge of the lawn and it moves in the right direction. We see very little movement in fairy rings if they are present near to the rotting stumps of previously large trees.”
So if you have a fairy ring the addition of a wetting agent (washing up liquid can be used by the home gardener at a few drops only to a watering can) can help but if it will not shift maybe some professional help with a commercial fungicide can do the trick.