Coming up below are 11 ways to use hydrogen peroxide for plants including the different dilution rates and how to apply it depending on the problem you want to treat or prevent...
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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. A chemical-free alternative for cleaning and plant care.
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.
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 plants, hydrogen peroxide is used to prevent and treat a range of nasties, while promoting better health, restoring a healthier, oxygen-rich balance for our indoor plants to thrive in. That includes a long list from treating root rot to killing fungus gnats and more (all coming up below).
And for around the home, hydrogen peroxide has become a popular alternative to chemical-based cleaners. Used for everyday cleaning of surfaces including cleaning fruits and vegetables, to tough jobs such as disinfecting kitchen surfaces, killing salmonella on cooking surfaces, killing and cleaning mould in bathrooms, cleaning up pet mess and removing stains.
What bacteria, mould and fungi can hydrogen peroxide kill?
The particular brand I use (called Forsana), has been tested to kill 99.99% of bacteria, viruses, mould and fungi including waterborne and foodborne diseases. Proven effective against coronaviruses such as SARS and Covid, E. coli, Listeria, Norovirus and Salmonella.
Is hydrogen peroxide safe?
Yes, hydrogen peroxide is safe for use around pets and kids. Asthma and allergy friendly. Completely safe for the environment. Hydrogen peroxide breaks down into pure oxygen and water. But if you have sensitive skin gloves are recommended when handling it. Other than that, no special safety requirements are needed when using the standard 3% hydrogen peroxide.
What type of hydrogen peroxide can be used on plants?
In New Zealand the brand I use is Forsana Plant Care Plus Hydrogen Peroxide > but for my international plant friends, look for 3% food grade hydrogen peroxide like Essential Oxygen 3% available on Amazon. Just watch out for additives as not all hydrogen peroxide is plant-safe (Forsana and Essential Oxygen are two that are plant-safe).
What plant problems can can you use hydrogen peroxide for?
The most common uses of hydrogen peroxide for plants include the following list, with dilution rates and application directions further below.
- Eliminates root rot.
- Supports growth of healthier roots.
- Treats fungus gnat infestations
- (as well as other pests such as aphids and mites)
-
Eliminates fungal infections.
- Sterilises potting mix.
- Cleans and disinfects pots and plant tools.
- Prevents algae.
- Sanitises and increases germination of seeds.
- Speeds up compost decomposition while preventing unpleasant odours.
In general, hydrogen peroxide works by increasing 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 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 rates below are based on using Forsana Plant Care Plus which is the standard 3% hydrogen peroxide normally used for plants. If you're using a different dilution rate such as 6%, you need to adjust the ratios below. For example, using 6% you need to either DOUBLE the water OR use HALF the hydrogen peroxide.
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 at least 2 days before treating the rest of the plant when using any brand of hydrogen peroxide as a foliar or leaf spray.
Hydrogen peroxide dilution rate 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.
STEP ONE: Remove the substrate, check the roots and cut off any infected roots first.
STEP TWO: Using equal parts 3% hydrogen peroxide and water, spray the roots thoroughly before repotting. If using 6% hydrogen peroxide, combine a 1/2 part 6% with 1 part water.
IMPORTANT: Avoid leaves as pouring at this strength on leaves can burn them. If the plant is known to have sensitive roots, you can rinse or spray with plain water after the hydrogen peroxide spray, before potting up.
OPTIONAL STEP: If is the plant has been badly infected and looks to be dying, you can try a hydrogen peroxide root soak instead. Unpot and remove the substrate same as step one and cut off any dead or dying roots. Then soak the remaining roots in 2 tbsp (30ml) hydrogen peroxide 3% mixed with 1 litre water for 6 hours. Replant into sterile potting mix and a clean pot. You can use hydrogen peroxide to sterilise the new soil and pot if needed (coming up below)
How to use hydrogen peroxide to kill pests (including Fungus Gnats)
Depending on where the pest feeds, either drench the soil or mist-spray the foliage. Using a very fine mist sprayer like the Mister 360 is recommended to increase coverage into hard-to-reach nooks and crannies, and increase contact with more pests.
To use hydrogen peroxide to kill fungus gnat larvae and pests that live and feed in potting mix: Wait until top layer of potting mix is dry and the plant needs watering. Mix a 1 to 4 part ratio of 3% hydrogen peroxide to water, for example: 1 cup hydrogen peroxide added to 4 cups of water. Then either spray or saturate soil by bottom or top watering as normal. If using 6% hydrogen peroxide, mix a 1/2 part of 6% to 4 parts water.
Depending on the insect, adults may continue to lay eggs. For fungus gnats it's best to use hydrogen peroxide to target the larvae in the soil, along with sticky traps to kill adults as well (or these sticky traps available here on Amazon if you're not in New Zealand). For Fungus Gnats, the larvae tend to concentrate in the top 5cms of the soil, so you can also regularly spray the top layer of substrate with the hydrogen peroxide mixture.
For pests that feed on leaves: You can also use hydrogen peroxide as a foliar / leaf spray. Use 1 part 3% to 8 parts water, for example, 125ml (half a cup) of 3% to 1 litre of water. If you have 6% hydrogen peroxide, use a 1/2 part 6% to 8 parts water.
When applying as a spray: Spray only (do not pour on leaves). Let air dry out of direct sunlight. Always spray-test one or two leaves the first time, especially for sensitive / thinner-leafed plants, at least 2 days before treating the rest of the plant, to check for a reaction.
Hydrogen peroxide for roots and plant health
Use the general maintenance dilution rate of 4 tbsp (60mls) hydrogen peroxide 3% per 1 litre water. Mist leaves or water onto soil every second watering to oxygenate roots, boost growth and enhance nutrient absorption.
To treat fungal or bacterial diseases
Using 3% hydrogen peroxide like Forsana, mix equal parts hydrogen peroxide with water. Or using 6%, add 1 part hydrogen peroxide to 2 parts water. Water into soil or mist infected areas to kill bacteria and fungi. If the plant is sensitive or you are unsure, treat a test area first at least 2 days before treating the rest of the plant to check for a reaction.
For sterilising seeds and speeding up germination
Using 3% hydrogen peroxide, mix 1 tbsp (15ml) hydrogen peroxide with 250mls of water. Soak seeds for 1 to 4 hours (check the plant type to determine how long is best), then plant. Using 6%, mix 15mls hydrogen peroxide (1 tablespoon), with 500mls of water.
To sterilise potting mix
Saturate the soil with 1/2 cup hydrogen peroxide 3% per 1 litre water or 1/2 a cup of 6% per 2 litres water. Put wet soil in a watertight container and leave overnight before planting. This kills pathogens such as fungi and bacteria including insect eggs and nematodes (roundworms).
To clean and disinfect pots and plant tools
Using 3% hydrogen peroxide, mix equal parts hydrogen peroxide and water. Pour into pots and wipe the sides. You can also soak tools in the mixture to prevent the spread of disease such as root rot. If using 6%, mix 1 part 6% to 2 parts water.
For hydroponics and aquaponics to treat algae and root rot
Using 3% hydrogen peroxide, mix 1 tbsp (15ml) hydrogen peroxide per 1 litre water. Add directly to the water system to help prevent algae and root rot. Also enhances nutrient absorption. If using 6%, mix 1 tablespoon (15mls) per 2 litres of water.
Harmful bacteria thrive in water with low oxygen content. Used in hydroponics, hydrogen peroxide boosts oxygen and helps combat low oxygen found in warm, room temperature water.
To disinfect greenhouse surfaces
If you've had an outbreak of pathogens like a fungal or bacterial disease, use undiluted 3% hydrogen peroxide and spray or wipe down the surfaces. If you have sensitive skin wear gloves when using undiluted.
To clean fruit and vegetables
Soak produce for 20 minutes in a mixture of 1 cup hydrogen peroxide 3% per 5 litres of water. Rinse before eating.
Compost accelerator
Using 3% hydrogen peroxide, mix 1 cup (150ml) hydrogen peroxide per 1 litre water. Spray onto compost pile or inside kitchen compost bin. Hydrogen peroxide helps speed up decomposition while also preventing unpleasant odours.
To clean a humidifier
Mix 1 part hydrogen peroxide 3% to 4 parts water. Fill your humidifier and leave it to soak for 60 minutes. Rinse out, and leave to air dry before using again or before storage.
Where can I buy hydrogen peroxide in New Zealand?
From me here at Love That Leaf :) I sell Forsana Plant Care Plus Hydrogen Peroxide > (if you're looking for the old Oxygen Plus by Good Clean Health Co, it's been rebranded Forsana (same company making it), and the formula's been improved).
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.