A deck turning green or black in Danville, KY almost always means algae or mold has found a damp, shaded spot to grow — it is a cleaning problem, not a sign your deck is failing.
Why Is My Deck Turning Green or Black?
Green staining is usually algae, which needs moisture and some shade to establish — common on the north side of a deck or under overhangs where boards stay damp longer after rain. Black staining is typically mold or mildew, which feeds on the organic dust and pollen that settles into wood grain or the surface texture of composite boards, and it thrives in exactly the same damp, low-sun conditions.
Fall is peak season for this in central Kentucky: wet leaves pile into corners and between boards, block airflow, and hold moisture against the deck surface for days at a time. Trex, one of the manufacturers behind the composite boards used on many local decks, publishes deck cleaning guidance that covers exactly this kind of surface growth.
How Do I Clean and Prevent It?
An oxygen-bleach based deck cleaner and a stiff (not metal) brush handles most green or black staining on both wood and composite boards. For wood decks, this is also a good moment to check whether it is time to stain or reseal — a fresh sealant coat sheds water instead of letting it soak in. Keeping leaves cleared and confirming your under-deck drainage is actually routing water away, not trapping it underneath, keeps the growth from coming right back.
Common Questions
Is a green or black deck ruined?
No, in almost every case this is a surface growth problem, not structural damage. Cleaning and improving airflow and sun exposure usually restores the deck’s appearance completely.
Can I use bleach to clean my deck?
Regular chlorine bleach can discolor or fade composite decking and is harsh on wood fibers. An oxygen-bleach deck cleaner is the safer choice for both wood and composite boards.
How often should I clean my deck to prevent this?
Twice a year is typical in Danville — once in fall after leaves drop and once in spring — with a leaf-clearing pass anytime debris piles up between boards.
Related: Deck Staining & Sealing | Under-Deck Drainage | Deck Inspection & Safety
Not sure if cleaning will fix it or the deck needs a closer look? Get a free estimate or call or text (859) 310-1209.
Source: Trex deck cleaning guidance.
Last updated: September 9, 2026