Despite all your hard work and time it can be frustrating if your garden looks less than perfect. Maybe your plants are struggling. Mold or fungal issues could be taking hold no matter how hard you work. Luckily there is a solution.
Using hydrogen peroxide for plants and the garden can help to cure a myriad of issues. It is great for promoting root development, treating fungal disease, curing infestations and removing mold.
If used correctly hydrogen peroxide for plants is far more effective than many store-bought or organic solutions. It can also be used without fear of contaminating your soil.
This guide to using hydrogen peroxide for plants explains how the chemical can boost your garden. We will also explain how to safely use and store the chemical.
What is Hydrogen Peroxide?
Before learning how to use hydrogen peroxide for plants, it is important to understand what this chemical is.
This is a sharp smelling, colorless chemical that looks like water. It is commonly used in a range of household cleaning products and disinfectants. You can also use hydrogen peroxide to:
- Disinfect small cuts or wounds,
- Treat boils and acne,
- Sterilize household cleaning products,
- Kill mites and pests,
- Remove algae from home aquariums,
- Bleach your hair.
In the garden it acts as an organic treatment as well as a mild antiseptic.
It is important to note that the chemical is often sold in diluted or watered down solutions.
Different Types of Hydrogen Peroxide
This common chemical is available in a number of different strengths or dilutions. The most commonly sold dilutions are:
- 3% or household, this dilution is commonly used to disinfect small cuts and wounds, gargle or as a mouthwash. This dilution can also be used to disinfect household surfaces.
- 6 to 10% or hair bleach. This dilution is commonly used to lighten hair.
- 35%, food grade. Despite the name this is a strong solution that should not be consumed. Swallowing a food grade solution can make you seriously ill.
- 90% or industrial strength. Again, a strong solution. Consuming even a small amount of this strength solution can be fatal. Industrial strength solutions are considered toxic to touch, breathe and drink. Used in commercial businesses to bleach fabrics and textiles this strength solution is not safe for use in the home.
How Does it Work?
Hydrogen peroxide has a similar chemical composition to water, its chemical formula is H2O2, similar to water’s H2O.
The extra oxygen in the chemical helps to aerate the soil, promoting root growth. This, in turn, helps flower and vegetable roots to increase nutrient and moisture uptake. The chemical can even be used to improve compacted or clay soil types.
Keen gardeners know that their flowers and vegetables often respond better to rainwater than a soak from a garden hose. This is because rain is a natural peroxide for plants. Using hydrogen peroxide for plants acts as a substitute for rainwater, boosting your prized specimens in a number of different ways.
Rainwater boosts growing flowers.
You can use hydrogen peroxide for plants as a mild antiseptic. Made up of hydrogen and oxygen this chemical is an ideal treatment for algae, fungal, bacterial and nematode issues, all of which are averse to oxygen.
11 Ways to Use Hydrogen Peroxide for Plants
As long as you get the mixture right, it is easy to use hydrogen peroxide for plants.
When treating, aim to soak the soil around the root system. This helps to get rid of fungi, spores or mold.
How much you use depends on the concentration. A good rule of thumb is to mix one cup of household strength Swan Hydrogen Peroxide in 32 cups of water. This is ideal for treating flowers and vegetables growing in the garden, pots and planters.
For indoor specimens mix one part 3% solution with 48 parts water. This can be safely misted onto the leaves of both indoor and garden plants.
Diluted solutions can be safely applied to indoor flowers.
Hydrogen peroxide can be used to help plants in a number of different ways. The following are the most common uses. As well as explaining how the chemical benefits your plants I also explain how to mix up the correct solution and how to best apply it to the plants.
1 Soil Aeration
Well aerated soil means that air is able to move through the growing medium. This enables the renewal of life sustaining gasses such as carbon dioxide and oxygen. These support the metabolic process of the plant.
In a compact soil these gasses, as well as vital nutrients, struggle to get through the soil. This means that your plant may struggle to flourish and survive. A lack of oxygen in the soil also slows down microbial activity. This in turn slows down the decomposition of organic matter which can allow toxic substances to form.
If your soil is compact the root system won’t spread out and develop. Upon lifting the plant you notice that the roots are squashed or compacted.
Rich, well aerated soil helps plants to thrive.
In contrast, well aerated soil promotes root growth and increases both the chlorophyll content of the plant and the photosynthesis rate. Finally, plants growing in well aerated soil are less likely to suffer from issues such as salt stress.
Use a weak 3% solution and mix with water. A ratio of one part hydrogen peroxide with two parts water is ideal. Place in a spray bottle and apply to the soil around the base of the plant. You can also add it to a watering can and soak the soil.
After the initial treatment, everytime you water the plant, use the hydrogen peroxide solution until your plants start to look healthier.
2 Treating Root Rot
One of the most harmful issues that can affect your plants, root rot is more common in heavy or waterlogged soils. It can also be caused by persistently overwatering plants.
Wet soil can prevent the roots from absorbing enough oxygen. Roots deprived of oxygen eventually start to decay and die. Additionally, weak roots are more susceptible to fungal issues.
While many of the fungi present in the soil benefit plant growth, some are malignant. Some of the most well known malignant fungi include:
- Armillaria which causes leaf drop and die back,
- Fusarium which causes stunted growth and the yellowing of the lower leaves,
- Phytophthora which causes wilting and the yellowing of leaves as well as plant die back.
Root rot can cause leaves to wilt and stunt growth. If allowed to develop the disease also cuts short the lifespan of the plant. As well as being a severe issue, root rot can be difficult to spot in its early stages. Often, by the time you notice it, it is too late to treat.
To treat root rot, mix one cup of hydrogen peroxide with 32 cups of water. As the sun sets, pour the solution onto the soil around the plants and allow it to soak in overnight.
If you want to learn more about root rot, including how to prevent it, our guide to identifying root rot is filled with useful information.
3 Disinfecting Gardening Equipment
As we have already noted as well as being beneficial for plants, hydrogen peroxide can also be used to clean and disinfect pots, garden tools, greenhouses and potting benches. This is particularly useful if you are treating a diseased plant.
Correctly cleaning your tools and work surfaces can help to prevent the accidental spread of disease. You can also use the solution to remove fungus from pots and potting benches.
Remember, even in a healthy garden, it is good practice to regularly clean and disinfect your tools.
Keeping your tools clean helps to prevent the accidental spread of disease.
To clean your garden tools, firstly wipe with a wet cloth, removing any dirt and debris,
Fill a bucket with a diluted hydrogen peroxide solution. To create the solution stir 2 cups of hydrogen peroxide into 1 gallon of water.
Dip the metal parts of your tools in the solution. Do not expose any wooden or plastic parts such as handles to the solution. This may cause them to deteriorate.
Dry your tools thoroughly to prevent rust.
The same solution can also be used to clean potting benches, work surfaces and greenhouse glass. Wear rubber gloves and wipe down your surfaces with a cloth dampened in the solution. After washing, dry with a clean cloth. If you are cleaning greenhouse glass, use newspaper for a shiny, streak free finish.
4 Disinfecting Your Growing Medium
Different types of plants require different types of growing medium. For example a cactus or succulent may struggle in a general purpose potting soil that retains lots of water. Instead it requires a special succulent potting soil.
This means that you may have lots of different types of potting mediums stored in a shed. On occasion you may need to reuse the potting medium. Knowing how to disinfect the potting medium means that you can safely reuse it without the risk of spreading disease around your garden.
Many types of potting medium also contain organic matter such as compost. You may even be making your own potting mix using homegrown compost. Sometimes, however careful you are with your compost heap, the material may become infected with bacteria or fungi. Knowing how to disinfect the growing medium before plants helps to make it safe.
To disinfect your potting medium, fill a clean, disinfected pot with the potting mix. Sprinkle a hydrogen peroxide solution, 1 teaspoon diluted in 8 ounces or one cup of water, over the top. Allow the solution to soak in before watering.
Water 2 to 3 more times over the course of a week. The potting medium is then safe to use for plants.
5 Sanitizing Seeds and Speeding up Germination
Soaking seeds in water before sowing helps to soften the shells and increase germination rates. Using hydrogen peroxide in the water helps to speed up the process. It also kills off any bacteria that the seeds may have picked up.
Pour some 3% or household solution into a small, watertight container and soak the seeds for 3 to 4 hours. This is enough to kill off any lingering bacteria.
After removing the seeds from the solution, rinse in clean, fresh water and dry on a kitchen towel before planting.
You can also place the seeds in a sieve or mesh bag and dip them in a diluted solution. Placing the seeds in a mesh bag keeps them in place making removal and handling easier.
This is just one of a number of ways you can improve germination rates.
You can use the chemical to speed up germination.
6 Boosting Root Development
You can use hydrogen peroxide to boost limp, lifeless plants. Applying the chemical correctly helps to aerate the soil. This makes it easier for the root system to spread out and develop. It also helps the roots to take on nutrients and moisture. In turn, this boosts the health and development of your plant.
While you can spray a solution onto the soil, watering it in helps to maximize absorption.
If you are using a 35% solution, mix 2 teaspoons into 1 gallon of water. Apply this solution every other time that you water your plants.
A healthy root system is vital to support above ground growth.
7 Fight Fungal Infections
Using hydrogen peroxide for plants provides an effective way to treat root rot, fungal growth and mold. If used correctly the chemical won’t harm your plants.
Using a 3% solution add 1 teaspoon or 5mls of chemical to one cup or 240 ml of water. Mix and pour into a spray bottle. Apply to the affected plant.
You can make a large amount of the solution and store it in a cool, dark place. Do not expose it to light. This degrades the potency of the solution. Remember to clearly label the bottle.
Water the solution well into the ground. Almost flood the plant and surrounding soil. If you are treating a container plant, water until liquid pours from the bottom of the pot and the soil looks waterlogged.
Drenching flushes the surrounding soil of any lingering bacteria. If you are treating container plants, don’t let them sit in trays of water. Water the plants in one place before moving the pot to another.
After watering, allow the soil to almost dry out before watering again. Drenching in this way should cure most fungal infections.
8 Insect Repellant
An infestation of harmful insects in your garden can be disastrous. Months of hard work and care can be destroyed in a matter of hours.
A diluted 1% solution of hydrogen peroxide is not only safe to use on plants it can also keep them pest free. To make a solution add 1 tablespoon of the chemical to a gallon of water and mix well. This can then be sprayed onto the plants, deterring aphids and adult pests and killing insect eggs.
Used correctly this solution is cheaper and more effective than many store bought products. It is also safe to use on your plants.
Use the solution to treat aphids infestations.
9 Hydroponics and Aquaponics
As well as using hydrogen peroxide for plants, you can also use the chemical to treat a lack of nutrients or bacteria in hydroponic systems.
Hydroponic systems can often struggle with a lack of nutrients and bacteria due to the warm atmosphere necessary for the system to function effectively. Additionally, harmful bacteria can thrive in warm water which has a low oxygen content.
You can use hydrogen peroxide to boost oxygen levels in your hydroponic or aquaponic systems. You can also use it to kill off any bacteria or fungal and mold spores that may evolve.
The chemical can be used to boost oxygen levels in hydroponic systems.
Use a 3% solution, applying 2 to 3 teaspoons per gallon of water or 3 ml per liter. If you only have the more concentrated 35% solution to hand, dilute it before use. Mixing 1 ounce of 35% solution with 11 ounces of water dilutes it to a 3% solution.
When you are not using the chemical store it in a black bottle. Light exposure makes the chemicals break down more quickly meaning it loses its potency more quickly.
10 Weed Killer
As we have already noted, a weak hydrogen peroxide solution for plants provides a good way to kill off bacteria and fungi.
A stronger solution, such as a 10% concentrate can be used to kill off weeds saving you hours of back breaking work with the weed whacker. You can also use a 3% solution, combine equal amounts hydrogen peroxide and warm water and mix well. Warm water helps to increase the activity of the chemical.
Simply mix up the solution and add to a Plastic Spray Bottle. This can then be applied directly onto the weeds. You can also mix the solution in a bucket and pour it over the plants.
If you are using the chemical as a weed killer, be careful not to expose it to any nearby plants. A concentrated solution kills plants as well as weeds.
This is an effective weed killer.
11 Water Treatment
An environmentally friendly way to keep your garden green lots of people harvest their own rainwater in a water butt. If you gather water, treating it with some hydrogen peroxide before using it on your plants helps to remove any contaminants such as harmful pesticides or chemicals.
You can also use the chemical to treat elements found in tap water such as chlorine.
For a 35% solution apply 2 mls of hydrogen peroxide for every gallon of water.
The chemical can also be used to treat water before using it.
Hydrogen Peroxide for Plants Safety Tips
Whether you use hydrogen peroxide for plants or in the home, you should always take care when handling the chemical.
The most commonly sold solution is usually 3% hydrogen peroxide. This can be used to disinfect cuts or even gargle with. Swallowing a tiny amount won’t cause you any harm. If, however, you consume a significant amount or a stronger solution it can raise the oxygen levels in your blood and cause significant harm.
Ingesting hydrogen peroxide can also cause:
- Irritation of the mouth, throat or stomach,
- Foaming at the mouth,
- Internal burns.
The stronger the percent solution the worse and more quickly the symptoms occur.
Inhaling significant amounts can also cause serious harm. Hydrogen peroxide can burn the skin and eyeballs. It can also kill you.
Despite having corrosive qualities, household strength hydrogen peroxide is unlikely to seriously harm your skin. However, it can cause minor skin irritations. It can also temporarily lighten the skin.
Skin contact with a stronger solution can cause burns, ulcers, blisters or scarring.
Swallowing food-grade or industrial hydrogen peroxide should be treated as a medical emergency. Contact poison control at 1-800-222-1222 immediately. You can also contact 911.
Safely Handling and Storing Chemicals
Do not heat or boil hydrogen peroxide. This is an unstable compound and can explode if exposed to heat.
Wear rubber gloves when handling the chemical. This is particularly important if you are using a high concentration of the chemical as a weed killer. While garden or work gloves offer protection in the garden, they are not waterproof and won’t protect your hands from the chemical.
Store your chemicals in a safe, cold and dark place away from any heat source or direct sunlight. Exposing the chemical to direct sunlight causes it to quickly lose its potency.
For extra safety store in a tamper-proof bottle or a Youngever Refillable Bottle with a tight seal lid.
Always clearly label your chemicals. This prevents them from being accidentally handled or used.
Keep your chemicals away from children and pets.
Used correctly this chemical can help you to cultivate a healthy, productive garden.
Using hydrogen peroxide can benefit your plants and garden in a number of different ways. Whilst not considered an organic treatment it is safe to use in organic gardens and, when handled correctly, is also environmentally friendly.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.