Slime Mold - JoanNusbaum 028-1APPEARANCE

At first glance, you may think your neighbor’s dog has vomited on your lawn. These flattened slimy or spongy masses, up to 2 feet in diameter, are living organisms known as slime molds. They may be white, yellow, pink or tan and often appear during rainy periods. Slime molds can actually travel several feet a day! And despite their name, they are not related to molds or fungi.


Slime molds feed on microscopic organisms that live in rotting plant matter. They are found on lawns, wood bark mulches, and even on the decaying leaves in your gutters. Damp weather encourages their spores to germinate and grow. When conditions dry out, puffball-like structures produce a new generation of spores. The slime mold will then break down, leaving its spores behind as a brown powder.


Although they don’t feed on your plants, any slime mold covering and shading a plant should be removed. No pesticides are labeled for use on slime molds. Instead, you can rake them up, bag them for disposal or disperse them with a strong jet from the hose. You can also do nothing. They will eventually disappear.

Contributed by Leslie Holzmann, Colorado Master Gardener. For more information, contact the Master Gardener Help Desk at 636.8921 or

Photo courtesy of Joan Nusbaum.