Prep first
Before you start
- Find out whether the wood is sealed, waxed, oiled or raw before you clean.
- Brush off loose growth, then wipe with a dry or slightly damp cloth.
- Test any cleaner in a hidden spot first, especially on fine furniture.
Green, gray or black growth on wood is usually algae, and sometimes moss, that builds up wherever the surface stays damp and shaded. It spreads on wind-carried spores and tends to come back, so a gentle clean that leaves the finish intact is the realistic goal. A patch that has lingered for months may take a second pass rather than one wipe.
Algae under water-sealed wood needs a lighter touch, so test a mold and mildew remover on a hidden spot first. On waxed or oiled wood, a wood furniture cleaner made for that finish is the safer choice than a harsh scrub. Dry the wood fully afterward, since damp and shade are what let the growth return.
Before you start
What wood furniture can take
Use with care5
- Water
- Chlorine bleach
- Oxygen bleach
- Solvents (alcohol, spot removers)
- Scrubbing and abrasives
Avoid2
- Soaking
- Heat, once the stain is out
6 items
What you'll need
Tap an item to get it on Amazon, or tick what you already have.
- Soft brush or broomLifts loose growth off the surface (opens Amazon)
- Soft clothsFor wiping with a damp, not wet, cloth (opens Amazon)
- A clean sponge (opens Amazon)
- Wood cabinet cleanerFor sealed furniture and cabinets only (opens Amazon)
- Hardwood floor cleanerFor surface-finished floors, the one your floor maker recommends (opens Amazon)
- Rubber glovesKeep the cleaner off your hands (opens Amazon)
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5 steps
Step by step
Step 1 of 52 minutes
Identify the wood's finish
Look at the wood and decide whether it's sealed, waxed, oiled or raw. If you can't tell, treat it as waxed or oiled and use only a dry cloth.
Step 2 of 53 minutes
Brush off the loose growth
Use a soft brush or broom to lift loose algae and moss off the surface. Brush from the outer edge of the stain toward the middle so the growth doesn't spread.
Step 3 of 55 minutes
Clean sealed wood with a wood cleaner
On sealed furniture or cabinets, spray a wood cabinet cleaner and wipe with a clean damp sponge or cloth. On a surface-finished floor, dampen a soft cloth with the hardwood floor cleaner the maker recommends, apply it to the stain and repeat as needed. If you don't know the maker, use a generic hardwood floor cleaner that a wood flooring professional recommends.
Tip. On fine furniture, test in an inconspicuous area first.
Careful. Wood cabinet cleaner stays off waxed, oiled, shellacked or unfinished wood.
Step 4 of 55 minutes
Wipe waxed, oiled or raw wood
Skip the cleaning spray on these surfaces and use only a cloth. On wax or oil finishes, wipe the stain with a dry cloth only, and on raw wood use a cloth that's dry or slightly damp, moving along the grain.
Step 5 of 55 minutes
Dry the area before you move on
Wipe the cleaned spot with a clean, dry cloth so no moisture stays in the grain. Once the wood is fully dry, check the stain in good light and repeat the clean on any patch that still shows growth.
If you'd rather buy than mix
Best products for algae on wood furniture
Choose a wood cabinet cleaner for sealed furniture and a hardwood floor cleaner for finished floors, and confirm the product is made for your finish.
Amazon Basics Microfiber Cleaning Cloths
How we picked these: each product is made for this type of stain, its maker doesn't warn against using it on wood furniture, and its directions fit the steps above.
Finished the steps? How does it look?
Nice work. Let it dry completely and check it again in good light. Here is what done looks like:
How to tell it's really gone →A faint mark usually needs one more round, not a stronger product.
Heavy buildup usually takes more than one round.
Heavy or long-standing buildup →When to call a professional →How to tell it's working
The growth should lift onto the cloth, and the wood should look even again once it dries. If the color stays put after the wood is fully dry, the growth has likely soaked into the wood, so treat it as a set-in stain.
What changes for yours
Adjust for your wood furniture
Water-sealed wood
Water-sealed wood is still a finish that can be damaged, so the change is in how gently you clean it. Keep to a dry or slightly damp cloth and never soak the wood to loosen the growth.
Water-sealed decks and fences fall under the Decks & Wood Fences guide, which covers heavier outdoor growth. Stay with the steps above for furniture and indoor wood.
Waxed or oiled wood
Wax and oil finishes change the cleaning method more than anything else. Wipe with a dry cloth only, and leave the cleaning spray out of it.
If you're unsure whether the finish is wax or oil, use the dry cloth and check the stain again once the wood has dried.
Raw, unfinished wood
Raw wood has no finish to protect it, so keep moisture to a minimum. Use a dry cloth or one that's only slightly damp, and move along the grain.
Skip the cabinet cleaner, and check for growth once the wood is fully dry.
Sealed furniture and cabinets
Sealed furniture and cabinets are the one case where the wood cabinet cleaner is used. Spray it, then wipe with a clean damp sponge or cloth, and test first on fine pieces.
If the spot still looks dull after one pass, repeat the wipe once before you try anything else.
Heavy or long-standing buildup
Old algae that has been on the wood for a long time can look permanent even after a careful clean. Growth that has dried into the grain takes longer to lift, so repeat the same gentle clean rather than switching to something harsher.
Let the wood dry fully, then check the stain again in good light before you decide anything else. Repeat the clean only on the spots that still show growth, not the whole surface.
If a dark mark stays after a few repeats, it may have gone into the wood itself, and cleaning won't lift it. That's realistic for stains that have been there for years, so set your expectations accordingly.
Vinegar, baking soda, peroxide and more
Do home remedies work on algae on wood furniture?
Most household remedies are a poor match for wood. None of them is needed, because a cleaner matched to your finish is the safer route.
Skip5Avoid1
What makes it worse
Mistakes to avoid
Don't wet-mop or steam wood floors
Wet mops and steam mops damage the finish, and over time they can damage the wood underneath. Wipe the stain with a damp cloth you can wring out instead.
Don't use ammonia or dust treatments on wood floors
Household dust treatments and ammonia don't belong on wood floors, even on a single spot. Stick to the cleaner your floor maker recommends.
Don't bleach raw or waxed wood
The bleach-and-water method is meant for sealed, non-porous surfaces such as painted wood. On raw or waxed wood it's the wrong pick, so use a damp cloth and a gentler cleaner instead.
Don't mix bleach with vinegar or ammonia
Chlorine bleach combined with ammonia, vinegar or other acids can release toxic gas. If you switch products, rinse the wood well and let it dry first.
Don't let bleach dry on the wood
A bleach solution that dries completely can stop a rinse from clearing it fully. Keep the area wet while you work and rinse with a garden hose when you finish.
When to call a professional
Bring in a certified wood flooring professional if the growth has gone into the grain, since resanding and recoating are their work. If the home was built before 1978 and sanding would disturb more than 6 square feet, the job needs lead-safe certification. Tell them how long the growth sat and which cleaners you have already used.
Questions
Is black growth on wood always mold?
Usually not. The black streaks people often mistake for mold or mildew are most commonly algae, and they're cleaned with the same gentle method.
Why does moss keep coming back on wood?
Moss takes in water through its leaves, so it thrives wherever wood stays damp, such as shaded spots that don't dry out. Clearing the moss and letting the wood dry gives it less reason to return.
Will algae return after I clean it?
It can. Algae and moss spread on wind-borne spores, so they can settle on wood again, especially in damp, shaded areas.
Can I use steam or lots of water to speed things up?
No. Steam or excessive water may damage wood, so it isn't worth the risk. Use a dry or slightly damp cloth instead.
Can I use chlorine bleach on wood?
Not as a routine cleaner. Chlorine is only a repair option for old moisture stains on floors, and the bleach-and-water mix is meant for sealed, non-porous exterior surfaces.
How can I tell if my wood has a wax finish before I clean off algae?
Dab a little mineral spirits on a white cloth in an out-of-the-way place. If the cloth picks up a tan or amber tint, the finish is wax, so you'll know to avoid bleach and use a damp cloth with a gentle cleaner instead.
Can a wood cabinet cleaner handle algae on sealed furniture?
A wood cabinet cleaner suits sealed furniture and cabinets, so it's the right pick there. Spray it on, then wipe with a clean damp sponge or cloth. On fine furniture, test an inconspicuous area first, and skip the cleaner on waxed, oiled, shellacked or unfinished wood.
Is a slightly damp cloth enough on raw wood?
Usually, a slightly damp cloth is the gentlest choice for raw wood. Wipe gently, don't let the wood sit wet, and dry the area before you decide whether it needs another pass. Bleach is meant for sealed surfaces, so leave it out of raw wood care.
Can dark marks left by algae on wood be fixed?
Often, but it's usually a repair rather than a cleaning job. Dark marks that have reached the wood can sometimes be lightened with a bleach treatment on sealed wood, so test a hidden spot first and rinse well. If the mark doesn't change, a wood flooring or furniture professional can judge whether it needs refinishing.
Algae on other materials
Other stains on wood furniture
Start from the bigger picture
How we know this
Every method, amount and warning here comes from university extension services, industry bodies and product makers. We read them, check every step for unsafe combinations and changed amounts, and write it up so you can follow it.