Best Way to Use Hydrogen Peroxide For Plants

Using hydrogen peroxide for plants may not be the magic bullet in the garden that we’ve been led to believe.

A woman pours a clear liquid from a bottle into a pink watering can
(Image credit: Valeriy_G / Getty Images)

How To Use Hydrogen Peroxide In The Garden

You may have heard that hydrogen peroxide for plants in your garden is helpful. It isn’t a secret that hydrogen peroxide has a plethora of uses around the home from cleaning the toilet to disinfecting sponges. 

So many in fact that one begins to doubt the veracity of these claims. So is it true? Can you use hydrogen peroxide on plants? Will hydrogen peroxide kill plants? There’s a lot to unpack here so keep reading to find out if hydrogen peroxide for the garden is beneficial or detrimental. 

What is Hydrogen Peroxide?

Hydrogen peroxide, often shortened to simply “peroxide” is a disinfectant, bleaching agent and oxidizer that is a pale blue liquid in its pure form and slightly thicker than water. It is diluted for sale to consumers and slightly less so for industrial use. 

Its first commercial use was to bleach hats in the 1800’s. Since then it has moved into the realm of everything from cleaning agents to tooth whiteners to rocket propellants. 

In 1858, Dro Benjamin Ward Richardson declared that hydrogen peroxide could be used to eliminate odor, effectively labeling it a disinfectant. For years it has been marketed as a go-to disinfectant for minor wounds. That idea is no longer popular since peroxide has been shown to do more harm than good.

Hydrogen Peroxide Hacks: Fact or Fiction?

Whether hydrogen peroxide is useful and safe for plant life depends on the claim. For instance, there is a claim that hydrogen peroxide can cure plant diseases, however, that may be too broad. Here are two hacks to consider if you’re thinking about using peroxide in the garden.

1.  Peroxide does sterilize surfaces and has been shown to reduce bacteria as well as some fungi. However, hydrogen peroxide works by immediately interacting with other compounds so quickly that it’s impossible for the disinfectant to move through plant tissues where a pathogen resides. So, this particular hack would be false. In fact, excess use of hydrogen peroxide on a plant may actually make it worse by drying the surface of the plant and killing off its beneficial microbes.

2.  Conversely, there is a claim that hydrogen peroxide can speed germination. True or false? It’s actually true, although it’s not always necessary. Hydrogen peroxide is said to increase oxygen, which then facilitates sprouting. Instructions say the seed should be soaked in a 3% or less solution for 30 minutes. But, at least one study has been done to prove or disprove this claim and there were several findings. It does not work on every type of seed, and the concentration of peroxide is key; too much, and the seed becomes unviable. 

Seeds produce peroxide on their own so there isn’t a need to provide it. How, why, and on what species it works still remain to be studied. So, while it does work sometimes, there are too many variables and really no need. 

Is Hydrogen Peroxide Safe for Plants?

The first hydrogen peroxide pesticide for use as a disinfectant on plants including fruits and vegetables crops was registered in 1977 and the EPA approved the registry. By September 2022, six pesticide products containing hydrogen peroxide were available for use. 

The approval was based on assessing risks to the environment and to humans. It was decided the risk was nominal, and the only recommendations were to tell users not to spray around active bee populations and to use personal protective equipment (PPE) when handling the product. 

 With all that in mind, the EPA says that hydrogen peroxide in low doses is indeed safe for plants. The caveat is of course, in the concentration. Too much can damage plants. Also, many of the hacks flying around are not necessary and there have been no studies to support or refute their veracity. 

How to Use Hydrogen Peroxide in the Garden

There are so many recommended ways to use hydrogen peroxide in the garden. Some of the claims are that it aerates the garden, can be used as a fertilizer, cures root rot and fungal diseases, disinfects soil, disinfects greenhouse and garden equipment, encourages root growth, kills weeds, repels insects, sanitizes seeds and speeds germination, and treats water. Let’s explore these uses:

1.  Some of these are definitely true. Hydrogen peroxide does sanitize garden tools and greenhouse equipment. However, commercial greenhouses don’t use it. Instead, they use hydrogen peroxide mixed with peroxyacetic acid because it works better. At home, many gardeners use rubbing alcohol to kill any pathogens on tools. And then, some are resoundingly false.

2. Peroxide removes harmful chemicals or pesticides found in tap water, so irrigation water should be treated prior to use. Hopefully, there are no pesticides in the tap’s drinking water.

There is likely chlorine in your drinking water. Hydrogen peroxide reacts with chlorine in water if the pH is above 7. This reaction becomes hydrochloric acid; corrosive to the eyes, skin and mucous membranes and presumably, not so great for plant tissue. At any rate, the amount of chlorine in your drinking water is negligible and not harmful to plants, so don’t add hydrogen peroxide. You don’t need to. 

At the end of the day, the use of hydrogen peroxide has not been extensively studied and, in fact, in some cases, it hasn’t been looked into at all. In all of the above claims there is either no reason to add hydrogen peroxide and/or not enough evidence of its benefit or detriment to plants.

Amy Grant

Amy Grant has been gardening for 30 years and writing for 15. A professional chef and caterer, Amy's area of expertise is culinary gardening.