Hydrogen Peroxide Foliar Spray for Growing Cannabis

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Cannabis growers are finding numerous beneficial uses for hydrogen peroxide in their gardens, both indoor and out, hydroponic and soil. Learn how to use hydrogen peroxide in various forms, including as a foliar spray, to grow healthier, more prolific and abundant cannabis.

What is Hydrogen Peroxide (H2O2)?

Chemically, hydrogen peroxide is just a step away from water. There’s even a small proportion of hydrogen peroxide in rainwater.

This could explain why you may have noticed plants get a visible, instant boost from the rain. Water, or H2O, is composed of two molecules of hydrogen and one molecule of oxygen.

When water bonds with another molecule of oxygen, it forms H2O2, or hydrogen peroxide. This small change can provide additional benefits to cannabis plants above and beyond the benefits of plain water.

Can Hydrogen Peroxide Cause Plant Damage?

Before ever using hydrogen peroxide on cannabis plants, one key factor to determine is whether it’s safe, as the answer in any given situation depends on the particular usage and concentration.

Hydrogen peroxide comes in a variety of volumes, or concentrations, rendering from mild and relatively harmless to potent and potentially dangerous. The concentrations of hydrogen peroxide are represented by the proportion of pure hydrogen peroxide to water by percentage in a particular solution.

Can Hydrogen Peroxide Cause Plant Damage?

Common food grade hydrogen peroxide, for example, is 35% concentrated. That means it contains 35% hydrogen peroxide to 65% water. This is a strong enough concentration that, undiluted, it could burn the eyes, skin and most other things with which it comes into contact.

As long as you use the proper ratio of hydrogen peroxide to water when you apply it, hydrogen peroxide is completely safe for nearly all plants. The right ratio of hydrogen peroxide to use in any foliar spray to avoid causing your cannabis plants any damage is approximately 3%, although some applications can use ratios as high as 35 percent.

How Does Hydrogen Peroxide Benefit Plants?

Hydrogen peroxide is an oxidant, which gives it powerful purifying, cleansing and detoxifying properties. As such, it can serve your cannabis garden in a number of ways:

  • Eliminate Fungal Infections – Pretreat cannabis seeds by applying a light dilution of hydrogen peroxide prior to planting to prevent fungal infections like mold and white powdery mildew. If your cannabis plants already have a fungal infection, use a more potent dilution to combat it as well as combat and prevent root rot. Apply the solution in a foliar spray directly to the affected portions. You can also drench the soil with the solution to kill off any spores.
  • Eliminate Weeds – Uniquely beneficial to soil gardens, including outdoor gardens, drenching your soil or other growing medium with a slightly more potent 5-10% solution of hydrogen peroxide can kill off any weeds that may grow there. Use the lighter dose as a weed preventative or for a light infestation and the heavier dose to combat a heavier infestation. In addition to pouring the solution into the soil of the affected plants, you can also apply it directly to the leaves and stems as a foliar spray.
  • Water Treatment – Treating water with chlorine to purify it is not possible with cannabis plants, as it will simply damage or even kill them. Unfortunately, most water treatments, and even a lot of tap water, contains chlorine. Pretreating the water you use to feed your cannabis plants with hydrogen peroxide uses the power of oxidation to eliminate all free radicals and other impurities in the water, whether in a soil or hydroponic garden. It will even counter any negative effects of chlorine contained in the water you’re using, as well as add extra oxygen to the water, which also benefits your plants.
  • Boost Root Growth – Hydrogen peroxide boosts root growth by feeding the roots additional oxygen, a source of nourishment and cleansing. To accomplish this, drench the soil in which your plants are growing with a medium solution of approximately 3-5% hydrogen peroxide. Use it on healthy roots to promote continued strong growth, and on weak or damaged roots to heal and strengthen them and help them proliferate.
  • Growing Medium Disinfectant – In addition to disinfecting your plants, drenching your soil or other growing medium with hydrogen peroxide disinfects the soil or growing medium itself. Place the soil or medium in a sterilized container and sprinkle the H2O2 over it. Then, for a few days afterward, water the soil with plain water, letting the excess drain out, in order to eke out any remaining H2O2 before planting in the soil or medium. Organic soil and growing mediums are particularly prone to bacteria and other disease-causing organisms.
  • Insect Treatments – Hydrogen peroxide is also a strong, natural insecticide and insect repellent. Add it to the soil and as a foliar spray to the leaves and stems to repel and kill common pests, like spider mites and white flies, and destroy their eggs. It’s even safe enough to use directly on the buds during the flowering phase. Best of all, hydrogen peroxide is much safer and gentler on your plants than harsh chemical insecticides. To use hydrogen peroxide as an insecticide or insect repellent, make a 1% dilution.
  • Germination Enhancer – Speed up the process of cannabis seed germination by treating them with a mild H2O2 solution. Instead of soaking your seeds in mere plain water to prepare them for a quicker, more successful germination, soak them in a mild H2O2 solution instead. Just add a teaspoon of hydrogen peroxide per cup of water you plan to use. Soak the seeds in the solution for 3-4 hours, then rinse them in plain water before placing them in damp paper towels to germinate. In addition to speeding up germination, this also can kill off any harmful bacteria the seeds contain, sanitizing them and helping to prevent diseases from forming in the plants that sprout from them.

How to Use Hydrogen Peroxide

You can spray a 3% hydrogen peroxide solution as a foliar spray directly to the leaves and stems of your plants as a general preventative as well as to combat an infestation. If you apply it to any flowering buds, make sure to shake the buds off of any excess wetness or have a light fan blowing on them to avoid causing new mold to form.

Soil Treatment

When applying hydrogen peroxide directly to the soil, particularly when treating a mold, mildew or pest infestation, make sure the diluted hydrogen peroxide solution runs all the way through and out of the growing container before finishing. Then, before resuming normal feeding or watering, allow the soil to dry out almost completely.

Disinfect Gardening Tools and Supplies

In addition to using hydrogen peroxide directly on your cannabis plants and growing mediums, you can also use it to disinfect your gardening tools, pots and supplies. You should do this in-between each growing cycle before reusing any growing materials or spaces.

a bottle of hydrogen peroxide

Simply soak the tools and supplies in a strong H2O2 mixture. This will help prevent you from spreading diseases from one crop to the next.

How to Use Hydrogen Peroxide in a Hydroponic System

To use hydrogen peroxide in a hydroponic system, make a 35% dilution by mixing 11 parts water with one part hydrogen peroxide. Once you do this, the molecules of hydrogen peroxide will begin breaking down in the water, resulting in the production of individual atoms of oxygen.

These oxygen atoms are free radicals that will destroy any bacteria or viruses with which they come into contact. And if two individual oxygen atoms happen to collide during this process, they will simply produce O2, which also support healthy cannabis plant growth.