6 Ways to Use Hydrogen Peroxide for Healthier Plants

Hydrogen peroxide is easy to come by in most households, and it’s surprisingly useful for gardeners. “Over the years, I’ve found it invaluable for tasks like sanitizing tools, cleaning algae and mold, and even managing certain pests,” says Brock Ingham, expert gardener and owner of Hamilton Landscaping & Co. “Unlike harsher chemicals, hydrogen peroxide doesn’t leave behind harmful residues, and it breaks down into water and oxygen, making it safe for the environment.”

Whether you want to banish plant pests or keep your garden tools clean, you can do a lot with hydrogen peroxide in your garden. Before you turn to expensive plant products, try these versatile uses for hydrogen peroxide to improve your plants’ health and keep your garden clean.

Use for Pest Control

“I use hydrogen peroxide to tackle pests in my garden without resorting to harsh chemicals,” says Anna Ohler, owner of Bright Lane Gardens nursery in Lake Ann, Michigan. “It’s great for soft-bodied pests like aphids, spider mites, and whiteflies. It works by breaking down their protective outer layer, but it’s gentle on my plants when diluted properly.”

To harness the pest-killing properties of hydrogen peroxide, mix 1 tablespoon of 3% hydrogen peroxide with 1 cup of water and spray it directly on the pests, Ohler advises. 

Sanitize Gardening Tools and Containers

Cleaning your supplies with hydrogen peroxide will help keep your plants healthy and disease-free. “One of the easiest ways to prevent the spread of diseases in the garden is by keeping tools and containers clean,” Ingham says. “I use hydrogen peroxide to sanitize everything from pruners to planting pots. It’s incredibly effective at killing germs, which can often linger and infect healthy plants.”

Scrub tools with water and plain dish soap first to remove any dirt and residue. Then, Ingham recommends spraying your gardening tools or containers with undiluted hydrogen peroxide to sanitize them. Let them sit for 5 to 10 minutes before rinsing thoroughly with water. 

Use for Plant Fungus Control

“For fungal problems like powdery mildew or black spot, I rely on hydrogen peroxide as a natural antifungal,” Ohler says. “I make sure to cover both sides of the foliage and repeat every few days if the issue persists. It’s an easy, affordable way to keep my plants healthy without synthetic fungicides.”

You can spray your plants with diluted hydrogen peroxide to get rid of fungal diseases. Ohler recommends mixing 1 tablespoon of 3% hydrogen peroxide and one quart of water. Then spray your leaves with the solution.

Remove Algae and Mold

If your greenhouse or garden space is plagued by unwanted algae or mold, a hydrogen peroxide solution will help. “Algae and mold can be frustrating, whether they’re growing in pots, on garden furniture, or on greenhouse surfaces,” Ingham says. “Hydrogen peroxide has been my go-to solution for this.” 

To kill algae and mold, dilute hydrogen peroxide with water by mixing 1 tablespoon of 3% hydrogen peroxide with 1 liter of water. Spray the solution directly onto affected areas in your garden. After letting it sit for a few minutes, scrub or rinse the area clean. “This method works incredibly well to break down the organic matter causing the growth, leaving surfaces fresh and free of residue,” Ingham says.

Prevent Root Rot

Root rot is a common problem for plants, and hydrogen peroxide kills the harmful fungi or bacteria causing the rot. “When I notice signs of root rot, like yellowing leaves or a funky smell in the soil, hydrogen peroxide is my go-to remedy,” Ohler explains. “I mix one part 3% hydrogen peroxide with two parts water and use it to water the plant. This oxygenates the soil and kills harmful fungi or bacteria causing the rot.”

Keep Hydroponics Healthy

If you have hydroponics, you can use diluted hydrogen peroxide to keep the water healthy for your plants. 

“For my hydroponics, I add about 1 teaspoon of hydrogen peroxide per gallon of water to prevent root rot and keep the water fresh and oxygenated,” Ohler says. “There are a lot of commercial products out there that are sold to prevent root rot and keep the water healthy, but they’re honestly mostly just hydrogen peroxide!”