Mushrooms in Lawns
Question. Mike: I have a problem with mushrooms appearing on my lawn after heavy rains. How can I get rid of them? Thanks!
- ---Ellinor in West Chester, Pa
- ---Kathy in Michigan
- ---Julie in Chappell, Nebraska
- ---Kim; somewhere in PA
And so here again are our rules for wise watering (which are wisEST for lawns): Water deeply and infrequently, and only if rain has been scarce. Never water an established lawn every day. In the most extreme circumstances in the hottest, driest climes and times, two overnight drenchings a week is the max. In normal situations, one long overnight drenching is all a lawn needs. (And 'overnight' means ending at 8am, not midnight; never let a lawn sit wet in the evening.) Infrequent, deep waterings help avoid all kinds of fungal problems and force the lawn to grow deeper roots, which crowd out weeds. (You'll find lots more watering details in this PREVIOUS QUESTION OF THE WEEK.
Drainage problems are more difficult to solve. Dr. Rogers suggests you begin with a good core aeration. Rent a machine called a core aerator, and run it over the lawn. It will pull out plugs of turf and dirt, reducing soil compaction and thus improving drainage. Do this in Spring or Fall; "anytime the grass is actively growing", says Dr. Rogers, with the caveat not to do it in the heat of summer even if you have a warm-season grass, as the stress it could cause to the turf might prove to be worse than the original problem.
One of our favorite lawn care experts, Iowa State University turfgrass Professor Dr. Nick Christians (who researched and developed the use of corn gluten meal as an all natural 'weed and feed' for lawns) agrees about moisture, but was also one of many we spoke with who doesn't consider most of these appearances a real 'problem'. "It's perfectly natural in really wet weather," explains Dr. Nick, adding that "in almost all cases, its no threat to the lawn, and the mushrooms will disappear when things dry out."
In fact, he says that the most common lawn mushrooms, the ones responsible for so-called "fairy rings," actually increase the nutrients available to the grass, creating areas of lush, dark green growth, often in the form of a circle. "These rings often show up in underfed lawns, because as the mushrooms break down organic matter, they feed the areas of the lawn inside their circle, making it a nice dark green. Feed the rest of the lawn," he suggests, "and the color should even out".
But don't bother attacking the mushrooms themselves, he warns, as the underground mycelium (kind of the 'root system' of the fruiting bodies we call mushrooms) is out of the range of rakes, shovels, fungicides and yes—even flamethrowers. "This problem often begins overtop of trash wood buried in the soil or tree roots left behind when a stump is left in the ground," he adds. "If that's the case, the mushrooms will stop showing up when they've done their job, which is to turn that wood into soil."
And he adds that those 'fairy ring' toadstools, some of which can be huge, are considered good luck! "Irish legend says that fairies sit on the mushrooms and have parties and smoke their pipes and such, bringing good luck to the household," he explains. An article I found at a website named "Less Lawns", agrees; they suggest you protect the mushrooms, surround them with garden gnomes and such, and then tell people you deliberately planted a fairy-friendly garden!
Our in-house mushroom maven, Paul Stamets, Director of the fabulous mushroom supply company Fungi Perfecti in Washington state, loves that idea—and adds that many lawn mushrooms, including the ones surrounding fairy rings, are native to grasslands, and so their appearance in a lawn is simply the way things are supposed to be. And, as grassland natives, he adds, they're natural heliotropes (sun lovers), which explains why they often show up in full sun rather than the shade we often associate with mushrooms.
"Enjoy their appearance", he agrees; "most are breaking down organic matter and actually feeding the lawn, many are quite beautiful, and one so-called 'fairy ring mushroom', Marasmius oreades, was the very first wild mushroom I consumed—after painstaking research made it clear that it was safe to eat." Just don't try such a thing unless a real expert can assure you that that's what your mushrooms are, warns Paul, as a similar species, the Clitocybe types, are poisonous.
Always remember the important adage: "There are old mushroom hunters and there are bold mushroom hunters—but there are no old bold mushroom hunters."