Moss growth can be a problem in shady areas. This guide is about getting rid of moss and algae on concrete.
Spread some lime over the area to get rid of the moss, or a cheaper method if you have a fireplace is to lightly spread some of the ashes over the area. If you wet it down, it sort of makes the gray disappear, but it gets rid of the moss.
By Mary from MI
How do you get algae off of concrete?
By Jim from Australia
Bleach and a scrub brush.
A couple of years ago I asked how to remove green algae from my concrete steps and driveway. Someone recommended a solution of vinegar and something else. Unfortunately, I forgot the something else. All I know is that it worked. Please help. Thank you.
By Cindy S.
You could use vinegar straight or mixed with water. You could also try bleach and water in a ratio of 2 parts bleach and 1 part water or any ratio. Be sure to wear eye protection around bleach. And you might have to scrub the moss and algae with a brush. You could also try pressure washing but not with bleach. Or try some products made to remove moss and algae from a big box store.
What fast and simple way can I use to remove green algae from concrete steps? Thank you.
By Cindy S.
We use a power washer with a weak bleach concentration in the water - works great! If you don't have access to a power washer, you will need to get a good scrub brush and use a solution of 1 gallon water with 1 cup bleach added and just scrub it off - make sure to wear gloves, and to rinse off the steps afterwards.
We have had a lot of rain these past 6 weeks in Connecticut. My front concrete steps are very green. Is this moss or is this algae? How do I get rid of it? Thank you.
By menopause from Suffield, CT
Don't know which it might be, but a pressure washer will get rid of it and make your steps look new again. (07/19/2009)
Household bleach mixed half with lukewarm water and a teaspoon of dawn dish liquid in a gallon plastic container applied by pouring and brushing with a push broom on a sunny day. Test the area you spray before rinsing off all of it. You may have to leave it on overnight if heavy growth.
Let it dry in the sun then rinse with a hand held pressure sprayer nozzle. You'll have to put in a bit more work, but it's much cheaper than renting a machine that doesn't do that much better. Wait until the sun is down more, still light enough to rinse off. I have done this several times and never had a single problem with plants or grass, but if large leaves are nearby, toss a cheap painter's drop cloth over whatever you're rinsing near it. Move it with you to cover any plant you need. We had excellent luck with it.
Although I didn't try this, the paint store (Sherwin Williams years ago) had a 'mildew retardant' packet for paint additive that I would have used along with it and which was available in a small packet. (07/21/2009)
Be environmentally safe and thoroughly spray (not pour directly because of run-off) with vinegar. It will kill whether it's moss or algae. Vinegar also kills even weeds in just a matter of hours.
Be sure not to let the vinegar spray get on any of your other plants or tree's leaves by spraying on a non-windy day and/or use a large piece of cardboard to keep the spray from hitting any plants next to your steps!
It also works best to do this on a warm and/or sunny day. :-) (07/21/2009)