How To Help You Plants With Hydrogen Peroxide: Mixing Charts

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Did you know you can use hydrogen peroxide for plants?

  • Hydrogen peroxide (H2O2) gives plants an added boost of oxygen for healthy root growth.
  • Dilute H2O2 for safe use, protect beneficial plants and avoid injury.
  • H2O2 helps with germination and seed sprouting.
  • Use peroxide to treat and help prevent bacterial rot, powdery mildew, and fungi.
  • H2O2 is environmentally friendly, breaking down into water.
Using Hydrogen Peroxide on plants with 3% solution. Give plants an oxygen boost, aid in germination, control fungus gnats.Pin

Many people know that hydrogen peroxide is used to clean wounds and as a personal care product. But this simple liquid has great benefits and works like a miracle product for gardening. H2O2 is very helpful and useful in all types of gardening.

Below we explore why a hydrogen peroxide solution may be a gardener’s best friend.

Handle Hydrogen Peroxide With Care! At Home and In The Garden

Hydrogen peroxide (H2O2) is a useful and mostly safe product. But it can burn and damage things. The concentration of peroxide you use matters!

Always use peroxide in a diluted form and handle it with care. Store your hydrogen peroxide in the container you purchased it in.

H2O2 is found in nature. But, the hydrogen peroxide that’s made and sold in stores isn’t considered natural. Even so, when using it in your garden, it breaks down to become water.

It is a great eco-friendly option, better than harmful pesticides, fungicides, and fertilizers.

You Have to Ask: Is Hydrogen Peroxide Safe For Plants?

Will Hydrogen Peroxide kill plants? No, H2O2, when used correctly, is safe for plants.

The Chemical Makeup of Hydrogen Peroxide… Very Similar To Water

Water’s chemical name is H2O. Two atoms of hydrogen and one atom of oxygen make tap water.

Hydrogen peroxide’s chemical compound name is H2O2. It is made up of two parts hydrogen and two parts oxygen. The addition of extra oxygen makes it very helpful for your garden.

Hydrogen peroxide is found in nature in things like water from rivers, rainwater, and our bodies. It is even found in plants. According to this NIH article, H2O2 “regulates plant growth, development, acclimatory and defence responses. During various environmental stresses the highest levels of H2O2 are observed in the leaf veins.

This NIH article states, “H2O2 play versatile roles in normal plant physiological processes and in resistance to stresses.

The extra oxygen promotes healthy root growth and can help roots absorb soil nutrients. Oxygen is bad for many diseases and things that are not good for us. Among them are:

How Can You Use Hydrogen Peroxide On Plants?

There are many uses for Hydrogen Peroxide in gardening with beneficial properties. Such as:

  • Preventative & Treatment: Helps discourage unwanted bacteria and fungi
  • Helps encourage healthy root growth
  • Infection Preventative
  • General Liquid Fertilizing Program
  • Seed Sprouting
  • Pest Control
Spraying hydrogen peroxide on a plant using a spray bottle.Pin

Can You Use Full Strength H2O2 on Plants?

Never use full-strength Hydrogen Peroxide on plants. H2O2 must be mixed with a lot of water before it’s safe for use on potted plants or in the garden. The right amount will benefit your plants, and too much will harm them or even kill them.

Most gardeners start with a 3% solution, the lowest product concentration. Even 3% peroxide must be diluted for safety. Here are some guidelines:

#1 – General-Purpose Drench or Hydrogen Peroxide Spray For Plants

How much peroxide for plants? One teaspoon of hydrogen peroxide in 8 ounces of water makes a good spray for:

  • Light liquid fertilizer (it is NOT a fertilizer)
  • Boosting plant growth

This light hydrogen peroxide mixture works as a preventative against:

General Spray Dilution Rate with 3% Hydrogen Peroxide

US MeasurementsMetric Measurements
WaterH2O2Water H2O2
1 cup – 8 oz1 Tsp240 ml5 ml
1 quart – 32 oz1 Liter20 ml
1 Gallon4 Liters80 ml
5 gallons13.5 Ounces19 Liters380 ml
For large doses, use a 35% Hydrogen Peroxide Solution
10 Gallons6 ounces + 4 Tsp38 Liters200 ml

#2 – Bacterial, Fungus & Infestation Treatment

Use a peroxide solution to treat sick plants, dropping leaves, or infested with pests. Add one tablespoon of H2O2 to every 8 ounces of water you use for treatment and care.

Dilution Rate Using 3% Hydrogen Peroxide For Treating Bacterial & Fungus Gnat Infestation

US MeasurementsMetric Measurements
WaterH2O2Water H2O2
1 cup – 8 oz1 Tbsp240 ml15 ml
1 quart – 32 oz4 Tbsp1 Liter62.5 ml
1 Gallon8 ounces4 Liters250 ml
5 gallons40 Ounces19 Liters1.2 liters
For large mixtures, use a 35% Hydrogen Peroxide Solution
10 Gallons6.5 ounces38 Liters198 ml

You can make up either of these solutions in advance to keep on hand for quick, easy use. Make sure to store your mixture in a dark-colored container with a tight-fitting lid. Label the mixture. Keep it in a well-ventilated, cool, dark place.

How Often To Apply H2O2 To Plants: Frequency Of Treatment

As a general rule:

  • Thoroughly drench healthy outdoor plants with a preventative mixture after every rainfall.
  • When dealing with ill or infested plants, apply every 3-5 days.
  • Keep a close eye on your plants.
  • Do not over-apply!
  • Let your best judgment guide you.

Note: Using too much or not using hydrogen peroxide correctly can harm plants by drying them out and killing helpful microbes. [source]

10 Ways To Use Hydrogen Peroxide In The Garden

#1 – Create A Sterile Growing Medium

Use a clean growing material like perlite or vermiculite when you start plant cuttings or growing seeds. Or sterilize your potting soil or homemade cactus potting mix. Here’s how:

  • Place the soil or potting mix in a watertight container
  • Soak the soil with a 3% hydrogen peroxide mixture.
  • Check the soil and turn it a few times to ensure all the mix is thoroughly drenched.
  • Let the mixture sit overnight.
  • Allow soil to dry out before use.
  • This treatment will kill off pathogens, nematodes, and their eggs.

#2 – Sanitize Your Seeds Before Sprouting

Pathogens will kill off your seedlings. Treat your seeds to reduce potential pathogens. Trevor Suslow and Linda Harris from UC Davis share how:

Tools needed:

  • Clean accurate cooking thermometer
  • Stove
  • 3% hydrogen peroxide
  • Cooking pan
  • Small mesh strainer
  • Room temperature water

Steps for treating your seeds:

  • In the cooking pan, add the 3% hydrogen peroxide solution
  • Heat the solution to 140° degrees Fahrenheit
  • Check the temperature with the cooking thermometer
  • Place the seeds in the mesh strainer
  • Immerse the seeds directly in the peroxide solution for 5 minutes
  • At 1-minute intervals, swirl the strainer for uniform treatment
  • Rinse the seeds with room temperature water for a full minute
  • Rinsing removes the peroxide before planting.

Use this seed sanitizing method when sprouting edible seed sprouts.

#3 – Speed Up Germination

The sanitizing method described above helps seeds get off to a good start. For years I’ve soaked seeds in very warm water overnight before planting. A study from Murray State University claimed it was clear that Hydrogen Peroxide and water (H2O) would continue to be frontrunners as the best available solutions.

After sowing seeds, water them with the – spray, drench solution – of (1 tsp H2O2 + 1 cup water) for the first week. This will give them a boost and help them as they germinate.

NOTE: Treatment with hydrogen peroxide nearly doubled seed germination of the Atlantic white cedar (Chamaecyparis thyoides). [source]

watering seedling with a boost of oxygen using H2O2Pin

#4 – Use A hydrogen peroxide soil treatment To Grow and Build Strong Plant Roots

Extra oxygen helps promote good plant root growth. We always advise having well-aerated soil. H2O2 can help by delivering an extra oxygen molecule.

A hydrogen peroxide soil drench with the light solution helps introduce oxygen, even in compacted or clayey soil.

Water mature plants with the spray, drench solution once a week. Soak the area around the roots thoroughly. You can also use this dilution strength when transplanting and starting root cuttings.

This agronomy study found that spraying H2O2 once a week:

  • Helped plants grow better
  • Collect more minerals
  • Stimulate bioactive compounds.

#5 – Treat Powdery Mildew Fungus

Do the leaves of your summer vegetables have a white, dust-like material on them? If you answered YES, it might be a disease called powdery mildew.

Make a powdery mildew fungal spray by mixing 4 tbsp H2O2 with 4 cups of water. Remember that hydrogen peroxide can burn sensitive tissues. It is always best to use a 3% solution in dilution when treating plants.

Before applying any spray, always test your peroxide solution on a small area.

#6 – Treat Bacterial Rot

In a 2021 study of non-expert gardeners stated:

  • 37% killed one or two indoor plants in a year.
  • 11.5 % killed six or more indoor plants in a year.

Bacterial infections kill a wide variety of plants.

Plants are injured from bad weather, poor pruning, insect damage, and diseases. When a plant is injured, germs can invade. This could make the plant very sick or even lead to its death.

A hand holding a watering can mixed with hydrogen peroxide, a natural and effective way to water and care for plants.Pin

Help prevent this bacterial spread with a regular H2O2 drench or spray solution. For example:

Drenching or spraying is important when you are pruning knockout rose bushes and trees.

Getting your tubers and bulbs ready for winter is a smart move.

  • Dip them in a 1:1 water and 3% hydrogen peroxide solution.
  • Let them dry out in the open air.
  • Make sure they’re completely dry before you put them away for the winter.

#7 – Controlling Wilts, Damping Off, and Fungus Gnat Pests

Hydrogen peroxide works best as a broad-spectrum fungicide. “All treatments significantly reduced damping-off and root rot/wilt severity.” [source]

  1. H2O2 produces free radicals that cause fungal cells to become brittle and leaky.
  2. It is effective soil and root treatment helping control, Fusarium wilt, Damping off, Phytopthora blight.

Note: Follow the Bacterial, Fungus & Infestation Treatment

Control Fungus Gnat Larvae

Use the following mix to control fungus gnat larvae:

  • One part 3% hydrogen peroxide
  • Four parts water


  1. Allow the top layer of your potting soil to dry
  2. Water your plants with the above H2O2 solution as normal.
  3. The soil will begin to fizz after application.
  4. Fungus gnats larvae die upon contact
  5. The peroxide will break down into harmless water and oxygen molecules.
  6. Repeat as needed.

#8 – Treating Hydroponic & Aquaponic Gardens

Hydrogen peroxide is used in aquaculture to treat diseases in fish caused by parasites, bacteria, and fungi. It works on different types of fish at different stages of their lives. [source Roy P. E. Yanong, Associate Professor University of Florida]

Fighting fungal infections is safer with H2O2 over usual chemicals. The reason is simple – the hydrogen peroxide breaks down and becomes water.

Related: Read our article on using Peroxide for Root Rot

#9 – Using Hydrogen Peroxide As A Disinfectant

H2O2 helps disinfect greenhouse tools, seed trays, pots, and surfaces.

Wear rubber gloves and goggles to protect your skin and eyes.

Sterilize tools and equipment, dip them into the solution, or spray it on and wipe it off with a clean, damp cloth.

The 6-9% solution effectively kills fungi, viruses, and bacteria.

A stronger solution (10%) can kill mold spores. It is also useful for removing and preventing mold and mildew on hard surfaces (e.g., greenhouse walls). If you use a very strong solution, exercise extreme caution.

#10 – Kill Weeds

A 10% hydrogen peroxide solution is recommended to kill weeds and moss. Pour it directly into pavement cracks in the late evening or early morning for best results. It will work best without direct sunshine.

When using this treatment, you must be very careful.

Wear protective gear! Avoid letting the solution come in contact with plants you want to keep. If you come in contact with this powerful product, quickly wash with cold, running water.

Using Hydrogen Peroxide Saves Money & The Environment

Although H2O2 requires safety measures, it is eco-friendly. Chemical fertilizers, pesticides, and fungicides do not break down like H2O2. Hydrogen peroxide becomes water after use.

You don’t need to worry about it:

… because it doesn’t do those things.

Hydrogen peroxide is not only very helpful, but also easy on your wallet for your gardening needs. Using a few easy methods, you can make safe and powerful tools to handle many garden problems.

If you want to add hydrogen peroxide to your garden care routine, first try it on your soil. Remember, you only need a tiny amount of H2O2 to help your plants and soil. Start with the general solution using the 3% peroxide.

You may never need to use the more concentrated strengths of commercial-grade peroxide. But if you do, be sure to treat them with caution and respect. Handle them wisely to avoid injury.

Sources: 1 | 2

Journal of Experimental Botany

UAF Indoor Plant Program (IPP) – Pest Management Information

Does Hydrogen Peroxide Affect Germination?

hydrogen peroxide use in the gardenPin

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