From treating fungal infections to removing root rot: 7 smart ways to use Hydrogen Peroxide for healthier plants

Time of India

20-07-2025

From improving soil quality and removing root rot to repelling unwanted garden pests and boosting seed germination,
hydrogen peroxide
offers several amazing benefits in the garden. Although commonly known as a mild antiseptic, it can work wonders for your plants. According to marthastewart.com, gardening experts Tammy Sons (TN Nursery) and Lucie Bradley (Easy Garden Irrigation) share surprising ways to use hydrogen peroxide for healthier indoor and outdoor plants.
7 ways to use hydrogen peroxide
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Treat
Fungal Infections
There are two fungal infections, namely powdery mildew and downy mildew, that can be treated using hydrogen peroxide. "I have used hydrogen peroxide as a mist on leaves when I first see signs of powdery mildew," Sons said. "It is by no means a sure thing, but it is a low-cost, easy, and generally safe trick to have in your bag of tricks."
To treat plants with downy or powdery mildew, mix three parts water with one part 3% hydrogen peroxide. 'Place this mixture in a spray bottle and use it to spray affected plants, including the underside of leaves,' says Lucie Bradley. She suggests doing this in the early morning so that the solution can dry before the afternoon heat. This treatment needs to be repeated every couple of days until the infection has gone.
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When using hydrogen peroxide with plants, Bradley stated that it is important to ensure that it is sufficiently diluted. Otherwise, it could damage or kill your plants. Always use a 3 percent hydrogen peroxide solution that is diluted with water.
Remove Root Rot
Potted plants can get root rot if they are watered too much or don't have good drainage, but hydrogen peroxide can help. Bradley said that the reason hydrogen peroxide can help is that when it decomposes, it releases oxygen and water. The extra oxygen gives roots better aeration.
To treat root rot, take the plant out of its pot, loosen the soil around the roots, and cut off any infected roots using clean scissors. Next, spray the roots well with a mix of 3% hydrogen peroxide and water (equal parts), then put the plant in fresh soil.
Prepare Soil
Even if your potted plants don't have root rot, treating their roots with hydrogen peroxide during transplanting can be helpful. Sons says she adds a couple of tablespoons of hydrogen peroxide per quart of water when moving outdoor plants into pots or transplanting a potted plant into a new container.
"I like to use it particularly with young, delicate roots,' she said. 'This gives them a little extra oxygen as they deal with transplant shock," she added. But she also warned that this solution should not be overused; otherwise, it can damage plant roots, especially those of younger plants.
Eliminate Aphids
Spray a mixture of hydrogen peroxide and water to help control and eliminate aphids. "Mix a solution of 1 part 3 percent hydrogen peroxide and 4 parts water," Bradley said. "Then add to a spray bottle and liberally spray the infested plant, ensuring you cover the aphids with the solution." For the best results, insects should receive direct contact with the solution. The hydrogen peroxide will damage the aphids' exoskeleton.
Eradicate Fungus Gnats
The hydrogen peroxide can also be used to get rid of adult gnats, as well as their larvae and eggs. "To kill the eggs or larvae in your plant's soil, first let the soil dry out," says Bradley. Then, drench the soil using a 4:1 solution of water and 3 percent hydrogen peroxide. 'You can repeat this process once a week until the infestation has gone,' she says. For the best results, aim for direct contact with the adult fungus gnats to kill the invading pests.
Encourage Seeds to Germinate
Gardeners often soak seeds before planting to soften the seed coat and help the seeds germinate better. "But you can also do this using a solution of 1 part 3 percent hydrogen peroxide and 8 parts water," says Bradley.
The seeds are required to be soaked in this solution for 30 minutes to an hour, then rinse in water. Then soak in water for an additional 10 to 11 hours before sowing. "This works best with larger seeds, which would usually take weeks to germinate," she says.
Sterilize Soil
When the soil is sterilized with hydrogen peroxide, it kills any bacteria and fungi. According to Bradley, there are two ways to do this. "For small amounts of soil—for example, houseplants—use a container where you have placed drainage holes in the base," she says. Then add the soil to the container and drench it with a 1:1 solution of 3 percent hydrogen peroxide and water. Mix the soil to ensure the solution is thoroughly combined. Once the soil is dry, you can use it for potting plants.
For larger amounts of soil, spread a thin, 1/4-inch layer of soil over a plastic sheet. Then, spray with a solution of 1/2 a cup of 3 percent hydrogen peroxide and 1 gallon of water.