Will Patio Cleaner Kill Plants? (Read This First)

When you patio gets all green and dirty, it’s tempting to just blast it with chemical cleaner and have done with it. However, this might not be the best idea.

Many patio cleaning products contain biocidal chemicals that can kill plants in your garden if you spray them on your patio. As an alternative, there are many organic patio cleaning options you can use that won’t have such drastic effects.

In this blog post we’ll consider the harmful side effects of some commercial patio cleaning products, and look at four natural alternatives that will leave your patio sparkling and your plants still flourishing.

Will patio cleaner kill plants?

Why Patio Cleaner is Harmful To Plants

Many commercial patio cleaners are designed to kill unattractive moss, mold, mildew, and algae. Most chemical cleaners claim to clean off your patio in a noticeably short time – some instantly. 

It’s only human to dream of instant cleaning solutions. Who loves to clean green goo off a patio? Answer: nobody! 

Instantaneous solutions are tempting – but they can have unintended, long-lasting consequences. Most patio cleaners contain chemicals that kill organisms – biocides. Chemicals that claim to kill living organisms instantly are strong ones – scary strong. 

The problem with using strong patio cleaners is containment. Patio cleaners are either sprayed in an aerosol or added to wash water, often a high-pressure washer. It is almost impossible to contain harsh, biocidal chemicals to just the patio. The wind blows. Water splashes around.

Harsh, biocidal chemicals can also harm: plants like grass or flowers, the bugs that live in those plants, pets that roll around in those plants, or toddlers who put those plants in their mouths. Even if you have no grass-eating toddlers, biocides can end up in your soil and groundwater.

There are lots of “no scrubbing necessary” chemical cleaners available. It’s hard to tell, looking at the obscure and unpronounceable ingredients, whether they are safe or not. Here are clues: does the patio cleaner recommend that you wear gloves? Is it “harmful if swallowed”? Does it cause skin irritation?

Here are some safe and simple ways to clean your patio. No gloves required.

4 Ways To Clean Your Patio Without Killing Plants & Flowers

Elbow Grease

Sure – sounds like something your grandmother would say. Think of it as “retro”. Think of the water you will conserve. Think of yourself as an Eco Warrior. Think of it as one, small, patio-cleaning way to show love to our planet.

The next warm, sunny day get your earbuds on or a Bluetooth speaker going. Conscript the kids. Then, move everything off the patio.

Blow or sweep all the leaves and other patio debris off (leaves are great for the compost bin). Get a bucket of warm water for each patio cleaning “volunteer”. Long handled scrubbing brushes will save your back. Stiff nylon brushes work well for stubborn areas. 

Scrubbing attachments for hand drills are useful when you get tired, or, rent a scrubbing machine. Check that areas aren’t being damaged, but the Elbow Grease method rarely harms patios.

For greasy spots around tables or grills, add a small squirt of a non-toxic dishwasher soap or Castile soap.

Sure – it’s not instantaneous. It might take a couple of days – but it’s only once a year! In the meantime, you are enjoying the great outdoors, getting some exercise, and enjoying those tunes.

Blasting Water

Water is a great, green way to clean a patio – if you live in a rainy climate. These days, many areas of our planet are in a state of drought, so cleaning your patio with lots of water might not be a good idea. In some places, using lots of water results in lots of water bills. Yikes! 

If you live in a drought-stricken area or if you are concerned with water conservation, then water washing is not a choice. Instead, see “Elbow Grease”.

If you live in a wet climate, though, pressure washing is for you. An amazing amount of green gunk can be pressure-washed off patios. Here’s a video showing great results using a rental pressure washer.

After a good sweeping or blowing, start with low water pressure. A nozzle on your hose may work well for most green gunk situations. If a nozzle just doesn’t cut it, you may have to rent or buy a pressure washer.

There are lots of pressure washers on the market. Most experts say for a patio with lots of mold, mildew, and algae, you need one with at least 2500 psi. If you are a solitary weekend warrior type, be sure to check out how much the pressure washer of your dreams weighs – they can be quite heavy. 

Pressure washers can be electric, or gasoline powered. If you decide to rent one, here’s a list of other ways to use a pressure washer. 

Little kids and big kids like to play in the hose on a hot day. Be aware that pressure washers have a LOT of pressure – pressure to decapitate flowers, draw welts on skin and damage your pavers. 

Before you attack with the washer, test out a hidden area. Make sure you aren’t damaging your patio. Pressure washers can damage natural stone, brick, and mortar. Slate patios have a natural cleaving property that are chipped by hard pressure washing.

Blasting water is fun and it can really clean up your patio. The neighboring flower beds will love you too.

Patio pressure washer cleaning

A Solution With Vinegar

White vinegar is a great “go to” cleaning choice. If elbow grease and power washing aren’t getting rid of mold and mildew, try a solution with vinegar.

Vinegar is a mild acid. It is a safe, effective cleaner inside and outside your house. A mild white vinegar solution is great to clean patio furniture or to kill weeds

For mold, mildew, or algae on your patio, mix a mild vinegar solution in a bucket: one cup white vinegar in one gallon of warm water. Find a hidden area for a test. If fizzing occurs, try using baking soda instead. 

Using a sprayer or a sponge, apply the vinegar solution to the moldy patio areas. Leave the vinegar solution to soak for one to two hours, then scrub and rinse.

If the mild vinegar solution is not working, try a stronger one. First, mix equal parts white vinegar with water, then try it out on a hidden area. Be sure the hardscape material doesn’t fizz. If fizzing occurs, stop, and go back to the milder solution.

If your hardscape shows no sign of fizzing, you can try full strength white vinegar. Be aware that a full-strength vinegar spray will kill weeds – and flowers and grass.

Baking Soda – Not Just For Cookies

Baking soda is a good “green clean” choice, either by itself or with vinegar. By itself, baking soda will not kill mold or mildew. Rather, it is a mild abrasive.

Baking soda (sodium bicarbonate) is a mild cleaning agent. It’s not acidic like vinegar – baking soda is alkaline. If your hardscape fizzed with vinegar (indicating dissolution), baking soda will work instead.

For a baking soda solution, mix 1/2 cup of soda into one gallon of warm water. If the area is greasy or oily, add 1/8 cup of non-toxic dishwashing soap. As always, first test a small, hidden area using the baking soda solution. Apply the soda solution with a sponge or spray bottle. Let the soda solution sit on the stained areas for up to an hour, then scrub.

Baking soda has all kinds of non-toxic uses in gardens: cleaning screens, cleaning deck boards, grills, soil amendment, combating compost aroma, fighting powdery mildew on roses, repelling slugs – it even grows sweeter tomatoes!

Baking soda is mildly abrasive. Sprinkle the powder directly onto a patio stain and then scrub with a brush.

Baking soda works well in combination with vinegar. Soda reacts with vinegar to produce bubbles – carbon dioxide gas. The natural bubbling action lifts dirt out of cracks and holes so you can wash it away. Since vinegar does kill mold, the vinegar-soda combo is ideal for your patio.

Sprinkle baking soda on moldy areas, then spray with vinegar. Scrub and rinse.

We’ve all ingested tons of baking soda – in cookies. Ingesting straight baking soda by the spoonful can be harmful, so watch those toddlers!

In Conclusion

With a little elbow grease (or a pressure washer), and using organic cleaning products – you can quickly and easily restore your moldy patio to its former glory.

There’s no need to use biocidal chemical products that can kill the surrounding plants when you spray it on. You’ll kick yourself if you’re trying to be careful and some of the spray drifts off onto your favorite flowers.

Baking soda and vinegar solution can be equally as effective – as can a combination of gentle pressure washing and a little scrubbing by hand for the most dirty areas.