It's a beautiful morning after a long rainy spell. You step outside to check out the yard, and there they are. Mushrooms have mushroomed overnight. They're under the shrubs. They're over by the tree. They're even smack dab in the middle of the yard. What causes the mysterious -- and frustrating -- appearance of these strange growths? You can blame it on the right mix of moisture, shade or cloudy weather, and organic material in the soil. When they combine, it's mushroom time.
Mushrooms are fungi, or rather, the reproductive part of fungi that live in the soil. Most of the time, the fungi just stay hidden, breaking down organic material. But, when conditions are right, they burst forth, like desert flowers blooming after a rain. Mushrooms spread spores into the air and then go away when the sun comes out or the soil dries up. You can keep mushrooms from appearing so often by changing the conditions in your yard.
Since mushrooms like shade, trim back some branches on nearby trees or shrubs. Extra sunshine keeps mushrooms in check.
If your lawn has standing water or remains damp for long periods after a rain, you soil may be compacted. Aerating your lawn would increase drainage. Better drainage helps decrease the moisture that encourages mushrooms. It also helps to increase the amount of oxygen that gets to the roots of your grass. If you have excess thatch in your lawn (over half an inch), you have a lot of organic material that absorbs moisture and acts as mushroom bait. Dethatching your lawn can help keep mushrooms away.
If you have an area where a tree used to stand, even if the stump is gone, the dead roots underground may encourage mushroom growth. If the stump is still there, you can have it removed. If it's gone, just keep the area well raked and aerated to improve drainage. Also, pet waste left on the lawn can bring out mushrooms.
If you have mushrooms, look on the bright side. Mushrooms are an indication that your yard has a lot of organic material in the soil. Mushrooms help break down that organic material, and make your soil more productive. If your shade and drainage aren't real problems, you can always just knock the offending mushrooms over and wait for the sun to come out.