Lawn Mushrooms in Idaho

Lawn Mushrooms in Idaho

At some point all lawn-owners will encounter mushrooms that seemingly spring up at random. If you are not used to seeing mushrooms in your grass, it’s understandable that you might be concerned. This article addresses common mushrooms that appear in Treasure Valley lawns, control methods, and what you should do if you think your child or pet has eaten unknown mushrooms.

Most importantly, if you think your child has eaten an unknown mushroom, stop reading this article and call the poison center at 1-800-222-1222 or your healthcare provider immediately!

If you think your pet has eaten an unknown mushroom, call the Animal Poison Control Center at 1-888-426-4435 or your veterinary emergency clinic. 

Mushrooms & Fungi

Understanding what a mushroom is and their relation to fungi can get confusing. I think the best place to start is understanding fungi. Fungi are simple microorganisms separate from plants and animals. There are millions of species of fungi, and most of them are beneficial and important to our ecosystem. Right now, your lawn is filled with beneficial fungi eating and aiding decomposition. Fungi are incredibly interesting, and they do some amazing things that go way beyond this short article. Just know that MOST fungi aren’t going to hurt you or your lawn.

One of the most fascinating things about fungi is how they reproduce. They can reproduce themselves in several ways. They can reproduce through cellular division like any other cell. Some fungi can infect a host, like a virus, using the host to replicate itself. These are the kind of fungi that damage a lawn. Fungi can also reproduce through the production of mushrooms or fruiting bodies. When conditions are right, the fungus can grow a mushroom that will then disperse spores.  

Mushrooms Common to Idaho lawns

Several mushrooms can show up in our lawns. Identifying every species can be difficult, but below is a collection of a few of the common species you may find in your lawn. Note that this is not a complete list. Also note that you should not eat any mushroom you cannot identify as safe.

Lawnmower’s Mushroom
Panaeolus foenisecii has many common names. In my experience, this is the most common mushroom you will find in your lawn. These small brown mushrooms will often grow in small groups throughout the lawn. While relatively harmless, it has been reported to have slight hallucinogenic effects if eaten. There are no chemical methods of control that will prevent this mushroom from appearing in the lawn. Keep your lawn on a regular feeding and watering schedule and physically remove them if you have concerns about children or pets consuming them. Follow this link for more info and identification. 

Fairy Ring Mushroom
Fairy rings can sometimes appear in lawns in the Treasure Valley. Often associated with a ring of darker green grass adjacent to stressed or even dead grass. It will often grow in a semi-circle with the mushrooms appearing along the edges. This is one of the few mushrooms that will appear with damaged grass. However, it isn’t the mushroom that is causing the damage. The fungus will grow what is known as a mycelial mat, smothering the lawn. There are no chemical controls that will stop the mat. Aerating the area and regular feeding will help the lawn recover faster. If you have a fairy ring in your lawn it will consistently reappear over several years. The mushrooms are not poisonous and are supposedly very tasty. Follow this link for more info and identification.

Death Cap Mushroom
Earlier in 2022, there was an identification of the Death Cap mushroom in Boise. At this point, its distribution appears to be isolated, and there have been no further sightings. Death caps are extremely poisonous. If ingested, medical attention should be sought immediately. They typically need hardwood or coniferous trees like oaks or spruce. Their cap usually gives them away as the skin is smooth and pale green. Here are a few links to review if you think you might have a death cap in your landscape.

Idaho Department of Health & Welfare


Why Are They in My Lawn?

Fungi are always present in our lawns. They provide a beneficial service and are an important part of our ecosystem. When conditions are right, some of these fungi will produce mushrooms. These conditions are usually during extended rains and fluctuating temperatures in spring and fall. Seeing a mushroom doesn’t mean there is anything wrong with your lawn. The presence of mushrooms is an indicator of healthy living soil.

Controlling Mushrooms

There are no chemical controls to stop mushrooms from appearing in your lawn. They have their time in the lawn, and once the conditions are no longer favorable, they will go away. Physical removal via mowing, raking, or digging are the only things you can do to remove the mushrooms from the lawn. But remember, removing them won’t prevent them from coming back. So, keep an eye out if you have children or pets in the area and you are worried about them ingesting them.