Slime Mold on Lawn: Harmless but Unsightly—What to Do

What You’re Seeing

White, vomit-like blobs that appear overnight, ranging from soda-can to CD size. When sprayed with water, they explode into dark brown dust. This is Fuligo septica, commonly called “Dog Vomit Slime Mold.”

It’s Not a Fungus—And It’s Not Dangerous

Slime molds are protists (Myxomycetes), not molds. They feed on bacteria, fungal spores, and decaying organic matter. They pose no threat to humans, pets, or grass. The dust is spores—their reproductive stage.

Management Options

• Do nothing. They disappear when conditions dry out.
• Rake or blast with water to break up the masses. This disperses spores but speeds aesthetic recovery.
• Reduce moisture. Water deeply but infrequently; improve drainage.
• Adjust pH. A light dusting of baking soda (pH ~8.1) or pelletized lime makes the surface less hospitable.
• Encourage predators. Earthworms, beetles, slugs, and snails eat slime mold. A healthy soil food web keeps populations in check.

When to Worry

If the lawn stays soggy for weeks, slime mold may indicate chronic overwatering or poor drainage. Fix the water issue, and the slime mold will vanish on its own.