What is the mysterious green substance on my deck, what is causing it, and how can I remove it?
Asked by Deniz Kılıççı 
7 months ago
Last Updated: June 13, 2024
What’s up with this green stuff on my deck? Do you know what causes it and how I can clean it off?
Bleach can be used to get rid of fungus.
Each year, spray bleach on the deck, pressure wash it, and then seal it. This area is likely the north side of the house, so get into the habit of doing this regularly!
To get rid of mildew, pressure wash it away and do this every year. You can also apply a bleach solution to prevent it from coming back. Be careful not to spray the bleach onto plants as it will kill them.
I accidentally spilled bleach on my deck and now it doesn’t absorb stain properly. There is a special type of wood cleaner that can help without causing streaks.
Sure thing! Here’s the rephrased text in a conversational tone: , right?
That green stuff on your deck? A bleach mixture can take care of it, just be careful not to make it too potent or you might notice some color changes on the wood.
‘t use a pressure washer on the wood. It can cause discoloration and damage if not used properly, and then you’ll have to refinish the whole deck to fix it.
You can find a spray called “mold and mildew release” at Home Depot.
I’m not sure about that, I’ve never personally given it a try.
Use an outdoor cleaner along with a pressure washer
It seems like someone celebrated St. Patrick’s day a bit too enthusiastically on your deck after drinking green beer.
Looks like there’s algae on your deck, maybe consider giving it a power wash.
Try using Ez House Wash – simply attach it to your hose and give everything a good rinse. It’s great for mildew.
Oxiclean does the job just like bleach but without the strong chemical odor.
When dealing with dirt, a power washer is the way to go.
To address the moisture issue, start by pressure washing the deck and letting it dry completely before applying a coat of stain. It’s important to seal the wood to prevent further absorption of moisture.
Check the cleaning solutions label. If it contains sodium hypochlorite, it’s basically just bleach but priced higher.
‘s Tri sodium phosphate is even more effective and can be found at Lowe’s, Home Depot, Menards, or any paint store. Be sure to follow the instructions carefully to avoid harming plants and risking burns! It surpasses bleach in performance
Is also effective when used in the washing machine to launder clothes
No way that paint is coming off, haha
Dang, I could really use a Soylent Green gif right about now.
If you’re dealing with mildew, most deck washes can help keep it under control. Tri-sodium phosphate is especially effective. Make sure to wash the entire deck, including the underside, before staining if you want to add color and seal it. Keep in mind that if you use Thompson’s Water Seal, this will need to be done annually.
The wood is soaking up water and expanding due to the presence of algae. To fix this, try using wet and forget, then rinse with a hose, allow it to air dry, and finally apply a coat of stain.
Mildew growth
Just spray some bleach on it. By the next day, it should be dead and turn black. Then just pressure wash it away.
Just plain algae… bleach can get rid of it. Then, just rinse it off with water.
You should use a power wash.
To get rid of moss or fungi, a power wash will do the trick.
Power wash to eliminate mold.
Definitely not mold, that’s for sure.
Is definitely not mold. 🫠
I think it’s due to the moisture not being able to dry properly. Personally, I’d go with power washing.
Reminds me of algae, not mold
It seems like algae, people find it on the sides of their house. Just Power wash it off or use DAWN and warm water to scrub it away
Not looking to argue haha but mold and algae are different – one is a fungus and the other is a micro plant. Either way, I’m not trying to be rude so apologies if it came across that way.
Hey, you’ve got it all mixed up! If you’ve got oak trees or maples in your area, that’s POLLEN! It’s green and can be easily washed off if you act quickly. I used to face the same problem every year back where I used to live because of those specific trees.
As light as it is, you could probably spray it with any bathroom cleaner and then rinse it off. I don’t think you need to resort to pressure washing just yet.
Nope, not mold. Just some tree pollen.
Looks like algae or moss. It tends to appear in damp areas on the less sunny side. You can try a light wash with Dawn dish soap and a rag or gently pressure wash with a brush.
Seems to be pollen. Just give it a few weeks and then use a pressure washer to clean it off.
The water is just dripping off the railings… The wood is wet, just hose it down and apply some oil to protect it
Deck cleaners can be used. Apply some of the solution and then use a stiff-bristle brush to scrub. Make sure to do a spot check first to avoid changing the color of your deck.
Spray the area with bleach using a spray bottle. Watch it vanish before you even reach the steps back into your house.
Notes that bleach can cause discoloration on wood, making it unsuitable for use unless you plan on painting over it.
You missed the mark, Amy.
Using diluted bleach effectively targets problem areas by penetrating deeply. It’s essential to address issues like lack of sunlight and ventilation properly to prevent recurrence. Proper maintenance is key to preserving the longevity of your decks. I have decades-old decks and tables that still look great thanks to my expertise in this area. Unlike Thompson deck stain, which only provides temporary results akin to applying Pledge wax, my method ensures long-lasting protection against grime and mildew.
Bleach, when used correctly, washed off, dried, and applied correctly with a good product, will not damage or change the color of anything! Failure to maintain it properly will result in all of those issues. Mold and decaying leaves, pine cones, branches, grease from grills, bird droppings, and dog waste will also not look appealing… Always maintain it, or you will need to replace it frequently…
Why don’t you work for Haarp and try to stop the rain
I’m not sure, maybe those weeds over there
Seaweed
Boogers are simply a fact of life
To get rid of mold or moss, simply use a stiff brush and cleaner. There are many cleaners available, you can use one of those or something you have at home.
No need to argue. There are plenty of products available to fix this issue. It’s a common problem for everyone.
Avoid power washing your deck at all costs. This can harm the surface, creating pockets that trap water and dirt. Instead, opt for a deck cleaner and a garden hose to tackle algae buildup.
Hey Charlie! Knowing how to properly power wash a deck can really give it a fresh new look. That green stuff you see is actually moss, as algae typically only grows underwater. And if you don’t believe me, feel free to look it up! Avoid using bleach on decks, as it can be corrosive and end up damaging the wood fibers.
Oh, moss, mold, and mildew. Just spray some diluted bleach on it. Let it sit for a couple of days. Then seal it with Australian Timber Oil stain. Repeat every few years. If you skip that, your deck will turn black, green, and super slippery like an ice rink all year long!
To start, steer clear of bleach. Mix one part blue ultra dawn with two parts water. This solution will effectively eliminate algae without causing damage to your deck or nearby plants. It’s also handy for getting rid of moss on lawns without harming the grass.