Peroxide treatment for tomatoes, tomato diseases and fertilizing 

Tomatoes are one of the most prized plants in the home vegetable garden. The sheer popularity of this easy-to-grow vine has encouraged development of hundreds of varieties, many of which are hybrids bred specifically to resist soil-borne diseases to which tomatoes are particularly vulnerable. However, even resistant varieties can succumb to infection. Should this occur, many tomato diseases can be easily treated with topical applications of 3% hydrogen peroxide*.

*NOTE: All mention of a 3% solution of hydrogen peroxide is a solution derived from diluting a 35% solution of PHARMACEUTICAL OR FOOD GRADE peroxide. THIS IS IMPORTANT. The 3% or even 8% peroxide you might buy in a retail outlet may NOT be pure. Many times other agents have been added to the solution that can harm or even kill plants.

To dilute 35% to 3%:  Into a dark container, mix 1 tablespoon peroxide to 1 gallon distilled water.  The use of safety glasses is highly recommended during this procedure. 

How it Works:

Hydrogen peroxide is a colorless, odorless liquid. When exposed to light, peroxide breaks down into water and oxygen. Additionally, when peroxide comes into contact with germs, bacteria or fungi, it degrades instantly. The reaction is a violent one, causing the substance to fizz and foam, killing any nearby microorganisms in the process. This makes peroxide an effective antiseptic, antifungal, antibacterial and bleaching agent.

CAUTION: While the byproducts of a peroxide reaction (water and oxygen) are essentially harmless, peroxide itself is considered corrosive and should be used with caution, particularly near the eyes or nose; it can also be harmful if swallowed and may trigger intense bouts of vomiting.

Hydrogen peroxide is usually associated with disinfecting and cleaning, but it can also benefit the growth of your plants. From sprouting seeds to your mature plants, hydrogen peroxide will give a boost anytime during the growing cycle. Hydrogen peroxide can kill infections and diseases on your plants and improve your hydroponic plants. The application of a hydrogen peroxide solution, whether sprayed or introduced into the soil, can create a stronger, healthier garden.

About Hydrogen Peroxide

Similar to the chemical structure of H2O, water, hydrogen peroxide, H2O2, differs with two oxygen atoms instead of one. The added oxygen, when used with plants, will increase the available oxygen to the roots, giving the plant stronger roots and resulting in a healthier plant. The common hydrogen peroxide found in your local drugstore only contains 3% H2O2, while food grade hydrogen peroxide is 35% and more beneficial to plants once it is diluted with water.

Seeds and Seedlings

When you soak your seeds in a solution of 1 cup water and 7-10 drops of 35% food grade hydrogen peroxide, your seeds will germinate faster and the developing roots will be larger and stronger. Seedlings watered with the same formulated solution will also grow faster and will have a stronger and larger root system with the seedling being thicker and healthier.


Watering your plants with hydrogen peroxide mixed with water will free up and add oxygen in the soil. This allows the roots to take up additional nutrients and water to feed the plant, boosting the plant’s growth. Two tsp. of food grade hydrogen peroxide mixed with 1 gallon of water used at every watering, or even every other watering, increases the plant’s strength and health. For hydroponic growing, use the same equation for your water grow tank. The hydrogen peroxide adds the extra oxygen atom to the grow water, something that some hydroponically grown plants usually have difficulty accessing.

Peroxide for plant food

Hydrogen peroxide (H2O2) is a cluster of hydrogen and oxygen molecules. In nature, hydrogen peroxide is found in rainwater and is very beneficial for natural vegetation. The tap water we normally use to water our plants does not contain hydrogen peroxide, but it can be added to enrich the water. Peroxide helps maintain healthy soil and allows roots to breathe better. Peroxide can be used as plant food for many types of indoor as well as outdoor plants

Purchase 35% food-grade hydrogen peroxide. The kind commonly found at drug stores (three percent) often has additional chemicals and should not be given to plants. 35% hydrogen peroxide is available at most chemical supply stores.

Add 2 tsp. of peroxide per gallon of water for potted plants. Add 1/2 tsp. of peroxide to a spray bottle full of water for spraying leaves. Double these amounts and spray on plants to treat fungal infections or moldy soil. Stir the water and peroxide mixture with a wooden spoon or stick.

Water your garden and lawn with peroxide using a fertilizer spray attachment on your hose. Add 6 tbsp. plus 2 tsp. of peroxide and fill the rest of the attachment with water for a 10-gallon spray attachment. Use 3/4 cup of peroxide in a 20-gallon spray attachment.

Purifying water with peroxide

Hydrogen peroxide is a chemical compound with many uses. These uses include bleaching hair, removing pollutants from the air and producing food. In addition, hydrogen peroxide can be used as a water disinfectant. Inhaling hydrogen peroxide can cause lung problems and the effect of chronic exposure to hydrogen peroxide is not yet known. Consequently, using hydrogen peroxide as a water disinfectant is generally considered a last resort in emergency situations.

Use a measuring cup to measure out 1/8 of a cup of hydrogen peroxide.

Pour 1 gallon of untreated water into a pot.

Mix 1/8 of a cup of hydrogen peroxide into 1 gallon of water in the pot and stir well.

Store the water in a clean, durable container and drink it within six months.

Tomato Diseases

Tomatoes are particularly prone to the development of fungal disorders — such as tomato blight, anthracnose, leaf mold and powdery mildew — and bacterial infections — such as bacterial wilt and bacterial canker. The hot, humid climates in which tomatoes flourish can also encourage the development of blossom-end rot, a disease that begins as a patch of decay on the bottom of the ripening fruit. Many tomato maladies are related to excess moisture and can be prevented by limiting watering. However, during periods of wet weather, this may not be possible, and additional measures may be required to prevent the spread of an infection.

Peroxide Treatment

At the first sign of a plant disorder, spray the affected foliage with 3% hydrogen peroxide. Be sure to coat both sides of the leaves and spray the soil surrounding the base of the plant; this will help eradicate any bacteria or fungus that may be affecting the roots of the tomato vine. Apply the spray 2-3 times a week until the disease is no longer evident.

Deterring Diseases

To help prevent development of tomato diseases, choose resistant varieties and be sure the plants are widely spaced to encourage the circulation of fresh air. To avoid blocking air movement, do not plant tomatoes near shrubs, walls or solid fences. Water tomatoes in the morning to give the leaves adequate time to dry, and do not work with the plants while the foliage is still damp; this encourages the transfer of diseases from one plant to the next.

Take care of infected plants immediately and remove those that do not respond to treatment. DO NOT add to your compost pile. Many of these organisms will survive for years in compost and soil.

Tobacco mosaic: This nasty infection is carried by tobacco (as in cigarettes) and can occur when a spore from infected tobacco gets mixed with your tomato plants. It’s a killer. We do not allow smokers or smoking in or around our greenhouse or gardens because of this.

Hydrogen peroxide can also boost the growth of your plants by cleaning the soil, or growing water tank, of harmful bacteria and fungus. The same mixture you use to water your plants automatically cleans the soil of bacteria and fungus that can slow your plant’s growth. When sprayed on plants infected with powdery mildew or mold, a diluted mixture of hydrogen peroxide will kill the disease.

Add to hydroponic growing and your plants will be protected from rhizoctonia, pythium and phytophthora, organisms which often attack hydroponic plants.

Peroxide mixtures for plants.

A hydrogen peroxide mixture is a useful solution for anyone growing tomato plants. This easily prepared mixture can be administered to tomato plants either by pouring it directly on the soil as the plants would normally be watered or by using the mixture as a spray. The method of application you choose depends on the reasons for applying the mixture.

Preparing Mixture

Making the mixture requires diluting hydrogen peroxide with water. When preparing a mixture for misting plants to prevent infection or mildew, add 1 1/2 tsp. of 3% hydrogen peroxide to 1 cup of water. When you apply it to many tomato plants and need a larger quantity of mixture, add 1/2 cup of hydrogen peroxide to each gallon of water. To remove fungus from plants or their soil, make up a stronger solution by doubling the amount of peroxide.

Applying to Soil

If the soil needs to be aerated or has mold, fungus, or bacteria growing in it, apply the mixture directly to the soil the same way you normally water plants. The hydrogen peroxide mixture controls unwanted growths in the soil by oxidizing them on contact, killing them with no harmful side effects. Because the mixture quickly breaks down after application, it will release water and oxygen into the soil, aerating it easily and efficiently.

Spraying Plants

When fungus or mold, are growing on a tomato plant, use a spray bottle to spray the mixture directly onto the plant itself. This kills the unwanted organisms on contact, whereas the absorption of the mixture through the roots does not affect them. This also helps to fight off and prevent bacterial infections in tomato plants. When working with an entire greenhouse of tomato plants, spraying the mixture generally throughout the air can prevent mildew in these moist conditions.

 Replenishing the soil. As noted above, the peroxide destroys bacteria, mold, fungus etc.  This means it has also destroyed a goodly portion if not all of the GOOD stuff in the ground.

Translated: Now you need to help your soil get back to it’s natural balance. The easiest and fastest way to get this going is through using what’s called a compost tea. There are a variety of recipes for compost tea and the following is my favorite.

In a 5 gallon bucket.Use a good natural compost to fill about 1/3 of the bucket. Add about 1/2 cup sulfur free molasses (i.e. Grandma’s molasses) fill the bucket to within 2-3 inches of the rim to allow for bubbling of the mix. Use a lid with a small hole drilled in it to allow for gas to escape. Place outside—-it’s gonna smell—-and plan on stirring 2-3 times over a 24 hour period. You can either dip directly from the bucket as you add the tea to the soil or strain it through an old T shirt for pouring. Do this after watering your plants. Like a sponge, the soil absorbs better if damp.

For information on soil testing and amending go here.

Information on plant diseases and their indications. 

Winter Composting Tips

















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