Every year I get several calls from my customers asking something like this, “What’s that slimy stuff growing in my bark mulch? It looks like a dog threw up in my shrub bed!”
With the rains and heat that we have had this past summer came some pretty strange, slimy looking stuff appearing in the shredded bark mulch in a lot of planting beds. Don’t worry…it’s not an invasion of the War of the Worlds, and a dog hasn’t thrown up in your flower bed. It’s something called slime mold (AKA dog vomit fungus), and usually appears in mid to late summer, or any time there are extended periods of heat and high humidity. The mold normally starts as a yellowish slime, morphs into a tan “powder puff” (poke it with a stick and you will see the reproductive spores puff out. Just don’t do it to more than one unless you want to spread the spores), and finally to a dark brown dried blob.
They’re only dangerous if you hate looking at really gross things. They are harmless to plants, and will eventually disappear on their own. If you want to speed this process, rake the mulch to promote drying them out. Unless you’re having company. Then, grab your shovel, scoop it up, and use it for a great practical joke.