Moss, Mold and Mildew: What Exactly Are They?

by Wet & Forget

moss mold and mildew what exactly are they, cleaning tips, outdoor living

Everyone seems to have a different name for the black and green growths you see on the exterior of your home or deck: moss, slimy green stuff, mold, black gunk, mildew . . . You know it when you see it, but do you actually know what it is? What is the difference between moss, mold and mildew? Here’s a mini science lesson to shed some light on the unsightly green and black growths you have outdoors.

What is moss?

Moss has very few uses to either animals or humans, but one of the things it can be used for is in gardening. When controlled, it can be a drought-friendly alternative to grass lawns that require plenty of maintenance.

What is mold?

Mold is a fungus that is made up of multiple cells and gets energy from the organic matter it lives on. Mold reproduces in spores, which can be airborne and are not visible to the naked eye. When you can see mold on a house or sidewalk, you are seeing a “colony.” A colony is a single organism that grows in long branching cells called hyphae.

How did it get there? Mold travels in airborne spores, and if it finds an environment it can live in that’s warm and moist and offers nutrients (which most surfaces do), it will grow. It grows by breaking down organic matter and absorbing it into the hyphae.

Mold isn’t always bad. It’s essential to nature, as it breaks down dead plants and animals, releasing nutrients in the process that other living organisms use. Penicillin comes from mold, so in some cases mold is beneficial to humans. However, a lot of mold spores can cause respiratory problems and allergic reactions. Also, mold on homes and sidewalks is unsightly and certain surfaces and finishes can be damaged by mold contamination.

What is Mildew?

This answer may surprise you. Unless you are a mycologist, a person who studies fungi, “mildew” is just another word for mold growth. Scientifically, mildew only grows on plants. Unscientifically, mildew refers to any type of flat mold growth.

Hopefully, this explanation helped you better the differences between moss, mold, and mildew. To us, all of these growths are your home’s number one enemy, and Wet & Forget is the best tool you can use to get rid of them. Moss, mold and mildew are invasive and will continue to grow on your exterior surfaces unless you take care of it with Wet & Forget, which will gently clean off the growth without damaging the surface it’s growing on. To see examples of mold and how Wet & Forget takes care of the problem, check out more of our before and after photos, like the one shown above!