How do you deal with roof moss and lichen growing together?
Short answer. Moss and lichen often grow side by side on shaded Georgia roofs, but lichen is the harder one to deal with: it forms tight, crusty patches that grip the shingle granules, so scraping it off usually takes the granules with it. The practical approach is to kill both with a labeled treatment, brush off the loose moss, and let dead lichen weather off over months rather than forcing it.
Telling them apart
- Moss: soft, green, raised cushions that sponge up water and lift shingle edges.
- Lichen: flat or leafy crusts, gray-green, pale green, or yellowish, often in round patches. It is a partnership between a fungus and algae, and it attaches tightly with root-like structures.
Why lichen is harder
Lichen grows slowly, often over many years, and anchors firmly into the granule surface. Pulling or scraping it off typically leaves a bare or pitted spot where the granules came away. Even after it dies, it can take months of weather to release. Patience protects the shingles better than force.
A combined plan
- Apply a treatment labeled for moss, algae, and lichen on asphalt shingles, on a mild, dry day.
- After the moss browns and loosens, brush it downhill with a soft brush.
- Leave dead lichen alone to fade and flake away with rain; spot-treat again if it persists.
- Clean gutters of the debris that comes off.
- Trim trees for sun and keep debris off the roof to slow regrowth. Zinc or copper strips near the ridge help.
What lichen tells you about the roof
Large, old lichen colonies usually mean the roof has been shaded and damp for years, and the shingles under them may already have lost granules. That can shorten their remaining life. For realistic lifespans and the signs of wear, see how long a roof lasts in Georgia, and for prevention, moss and lichen on roofs.