Cleaning mold, mildew and algae from your concrete patio

Natural Cleaners for Concrete Patios

by Dollar Stretchr Contributos

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Natural Cleaners for Concrete Patios

We have a concrete patio that either has mold, mildew, or algae forming on it. I went to a home improvement garden center to see what they recommended for cleaning it, and they suggested a pressure washer and a chemical cleaner that supposedly is safe on plants and pets. We really do not have the extra money right now to rent or buy a pressure washer, and I am worried about the chemicals in the cleaner hurting the plants in my planters that surround my patio on three sides. I have been nurturing them for years! I am not afraid of some hard scrubbing and elbow grease to get whatever is growing on there off, but does anyone know of any natural products or homemade cleaning recipes that work well on concrete patio surfaces?

Go Natural and Cheap

Boiling water kills most things that grow on concrete, and it's both natural and cheap. Just be careful as you pour it, so you don't get burned. Repeating the process a few times is best, and the dead matter will just wash away after a few days, if not later the same day. To prevent runoff onto your treasured plants, use almost anything as a barrier. Plastic edging, a board, or even a garden hose will work if the water isn't poured directly on them, but allowed to seep to the edge. I've had fantastic results on old concrete.

While added bleach or vinegar or salt work where there is no adjoining plants, all of those will cause damage to your treasured plantings. Baking soda will help to scrub the patio clean later, and some plants appreciate the soil's alkaline response to the runoff. But if you have acid-loving plants, be sure to adjust the soil following the scrub. It's easy to look up what pH your garden prefers.

Stick with Vinegar

I have used straight white vinegar on my moldy concrete (in my basement). The really bad spots took several applications and some scrubbing, but it worked well, and the vinegar odor dissipates fairly quickly.

Try Trisodium Phosphate

You'll find directions for using Trisodium Phosphate here on

Vinegar Kills Algae

The gentlest cleaner for outdoor algae is white vinegar. Just do not get it on the roots of the plants you want! It will kill weeds and algae. Soak a cloth and apply directly or make full or strong solution and wet mop it on.
Terri in Ft Lee

The Dynamic Duo

Try vinegar and baking soda. It will take several tries and lots of vinegar and baking soda. When we cleaned the mold off of ours, we waited until a warm evening after the sun went down and let this set overnight. Between scrubbing and a water hose, it finally came off and my plants were fine.

High Pressure Clean the Concrete

We live in a damp moldy part of the US. I use a high pressure hose to completely get everything off the patio cement. It's the best so far and you don't have to break your back scrubbing.

Remove the Light

If it is green in color, it needs light to survive. Cover it until it dies and then scrub well with bleach. Cover plants while scrubbing. Rinse well.
Van in AL

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Can you help this reader with a natural solution for her mildewed concrete patio? We have a concrete patio that...

Posted by The Dollar Stretcher on Monday, February 15, 2016

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