top of page

Why A Wood Fence Turns Green

Green algae, mold, or mildew are usually blamed when a wooden fence takes on a shamrock hue. Wood fences that have become green may be cleaned using a power washer, a scrub brush, or simply being replaced.

A sealer, treatment, or paint may stop a wooden fence from becoming green over time. Such treatments may reduce the likelihood of microorganisms colonizing the wood's pores. Wood that has already become green may be repaired by scouring, sanding, and priming. Painting, treating, or sealing the fence is an option after all the vegetation has died.

Why Is My Fence Turning Green?

Microscopic organisms use the wood's organic components as a food source. Because of its porous structure, wood provides a habitat for microbial life as it absorbs and stores water. The growth that begins on the fence might spread to the house's siding and eventually the inside.

Green Algae

Green algae is an innocuous fungus that thrives in damp, shady places. Prevention may be challenging if you reside in an area with high humidity or heavy rainfall. Rapid action is required to remove algae from a fence once it has become visible. If the algae are removed, but the environment is still unfavorable, more will grow again quickly.


When moisture and organic matter are trapped within the wood, mold may quickly spread. Green, black, or brown mold spots may develop on a fence. It's harder to eradicate than green algae, but its byproducts may cause damage to wooden structures. Having plants too close to the wall might encourage rapid mold growth.


Mold and mildew are essentially the same things. However, mildew is far less severe and seldom causes significant harm to the wood. It's not relatively as benign as green algae, but it won't do as much damage as mold. But nevertheless, it must be eliminated immediately.

Ways to Prevent Future Fence Damage

Ruining the Fence's Appearance