How to use Hydrogen Peroxide (H2O2) for plants

What's the difference between H2O (water) and H2O2 (Hydrogen Peroxide)?

Hydrogen peroxide (H2O2), occurs naturally in rainwater and acts as nature's cleanser. It oxygenates soil and bodies of water, is non-toxic and safe to use around food, people and animals. Adding it when watering your indoor plants, mimics what Mother Nature does for outdoor plants every time it rains.

Hydrogen Peroxide is distilled water with an extra atom of oxygen. H2O means 2 hydrogens and 1 oxygen atom. The extra 2 in H2O2 means 2 hydrogens and 2 oxygen atoms, called hydrogen peroxide. 

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What is Hydrogen Peroxide used for?

In human health, hydrogen peroxide has been used at different strengths for everything from wound care to toothpaste and cleaning. For our plants, hydrogen peroxide is used by plant hobbyists and growers to prevent and treat a range of nasties, while promoting better health, restoring a healthier balance for our indoor plants to thrive in.

In New Zealand the brand I use is
 Oxygen Plus Hydrogen Peroxide 3% or 6% double-strength but for my international plant friends, look for 3% food grade hydrogen peroxide like Essential Oxygen 3% available on Amazon.


How does Hydrogen Peroxide help plants?

The most common uses of hydrogen peroxide for plants includes: Eliminates root rot while supporting growth of healthier roots. Eliminates fungal infections. Treats fungus gnat infestations. Increases oxygen, creating an environment that harmful anaerobic bacteria, mould, fungi and diseases dislike, but roots love, supporting healthier plants and naturally repelling pests and insects


How do you use Oxygen Plus Hydrogen Peroxide?

The dose depends on what you need to promote or prevent. Find the issue you need help with below to check the dose before use. Please note the rates below are based on using Oxygen Plus 3% for Plants. If using Oxygen Plus 6% you need to either halve the amount of hydrogen peroxide, or double the amount of water below.

*Please note some leaves are more sensitive to foliar sprays than others, including Peace Lily and Orchids. Take the same precautions as any treatment applied to leaves. Either avoid spraying on plants with sensitive leaves, or always do a test spray on a couple of leaves 2 days before treating the rest of the plant when using Hydrogen Peroxide as a foliar spray*


Hydrogen peroxide to treat Root Rot

If caught in time, there is hope. H202 kills the bacteria and fungi in the soil responsible for root rot, and restores oxygen to help remaining roots recover faster.  Directions: 1:1 ratio of Oxygen Plus 3% and water. Bottom water or top water so potting mix is fully saturated. Avoid leaves (pouring at this strength on leaves can burn them). 

Pests and Insect Repellent (including Fungus Gnats!)

Use during watering for root pests, or as a spray to help repel insects that feast on leaves.

For larvae and pests living in potting mix: Wait until top layer of potting mix is dry and the plant needs watering. Mix 1:4 ratio. 1 part Oxygen Plus 3% to 4 parts water (eg: 1 cup to 4 cups). Either spray or saturate soil by bottom or top watering as normal. Depending on the insect, adults may continue to lay eggs, so best used in conjunction with treatment such as sticky traps to kill adults as well (sticky trays available here on Amazon if you're not in New Zealand). For Fungus Gnats, the larvae tend to concentrate in the top layers of the soil, so you can simply spray the top layer instead of fully watering.

For pests that live on and eat leaves: Mix 1:1 ratio. Lightly spray the entire plant. Best used in a fine mist spray bottle. Spray only (do not pour on leaves). Let air dry out of direct sunlight.

To support healthier, faster root growth

H2O2 provides extra oxygen to roots for growth and germination:

To sanitise seeds: Use undiluted H2O2 3%. Put seeds in a container that can be sealed. Pour Oxygen Plus to just cover seeds. Seal and soak seeds for 4 hours. Rinse with water.

To speed up germination: Mix 30mls H2O2 3% with 2 cups of water (a measuring cup makes it easy to get the right amount). Soak seeds overnight, then plant as usual. 

For planted seedlings: Spray with H2O2 solution of 1 part H2O2 3% to 32 parts water (eg: around 30mls per 1 litre - measuring cup recommended).

For established plants: Mix 1:1 ratio of 3% H2O2 and water (eg: 1 cup of each). Bottom or top water as usual (water soil only, do not pour on leaves).

For Hydroponics and Aquaponics

Harmful bacteria present in hydroponic gardens thrive in water with low oxygen content. Used in hydroponics, H2O2 3% boosts oxygen and helps combat low oxygen found in warm, room temperature water. Mix 2 to 3 teaspoons to 3.7 litres of water. Pour over plants.

To treat Potting Mix before use

Disinfect organic potting mix to kill bacteria and diseases before use. Spray or sprinkle 1/2 a cup of H2O2 3% over the potting mix before use, until lightly damp, and mix in thoroughly before potting up. You can also mix 1:1 in a spray bottle and mist the surface generously, so when mixed through the entire potting mix is lightly moist.

To eliminate Fungal Infections

When the plant needs watering, flush water with a 1/4 cup of H2O2 3% with 4 cups of water. Water heavily until the mixture drips out the drainage holes and the soil is fully saturated. Make sure to tilt the pot as you go to cover all areas of potting mix. 


To clean a Humidifier

Mix 1 part H2O2 3% to 4 parts water. Fill your humidifier and leave it to soak for 30 to 60 minutes. Rinse out, and leave to air dry. 

For all 50+ uses for Hydrogen Peroxide, see more here 


Where can I buy Hydrogen Peroxide in New Zealand?

From me here at Love That Leaf :) I stock the Oxygen Plus 3% Hydrogen Peroxide which the doses and directions for use above is based on, and also the new Oxygen Plus 6% Double-Strength (for that you either halve the H2O2 dose above, or double the water). 


Where can I buy Hydrogen Peroxide in the USA?

You want to look for 3% food grade hydrogen peroxide like Essential Oxygen 3% available on Amazon.

*Please note some leaves are more sensitive to foliar sprays than others, including Peace Lily and Orchids. Take the same precautions as any treatment applied to leaves, and either avoid spraying on plants with sensitive leaves, or always do a test spray on a couple of leaves 2 days before treating the rest of the plant when using Hydrogen Peroxide as a foliar spray* 


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