Your gutters should never have growth in them. I visited the post office today and it looks like grass growing in their gutters. Typically, what happens is when you have heavy forests behind you, there are leaves flowing, acorns, and other things that can lead to growth in your gutters. Then the worst thing that happens is you have your gutter not functioning it’s now leaking. This could lead to the seam being broken or cracking and that’s going to probably create a leak issue inside with the downspout to the left not operating and no one’s paying attention.
Don’t let this happen to your property, be clever as a professional