PSA: I used to think moss was bad for trees until I saw a study from UW Madison

3 comments

3 Comments

lilykelly14d agoMost Upvoted

A little bit of moss on a mature tree's bark is usually fine, nothing to worry about. The real issue is when moss covers the branches or trunk so thick it traps moisture, then you might see rot or bugs moving in. I had a big oak in my backyard that had moss for years, never hurt it a bit. Just keep an eye on it and if it gets too thick, gently scrape some off in dry weather.

henderson.vera14d ago

Wait, is it really that simple though? A friend of mine had a beautiful old maple in her front yard with a light moss covering for ages, and she never touched it because she heard the same thing you're saying. Then last spring after a really wet season, she noticed the bark underneath was all soft and spongy when she finally checked it, and the whole tree had to come down because of internal rot. So I guess the lesson is that a little moss might be okay, but you really need to keep an eye on it and not just assume it's harmless forever.

murphy.linda14d ago

Moss is more than just harmless though, it can actually be a warning sign. If you have moss growing thick on a tree, it often means the tree is already stressed or slow growing, not that the moss itself caused the damage. I read that same UW Madison study and they pointed out moss thrives on trees with thin canopies because sunlight gets through, which usually means the tree is already struggling. Plus trying to scrape it off can damage the bark you want to protect, especially in dry weather when the bark is brittle. Have you ever had a tree that looked fine until you started messing with the moss?