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What does hydrogen peroxide do for orchids?

Hydrogen peroxide is a commonly used household item that also has many applications for orchid care. When diluted properly, hydrogen peroxide can help treat several fungal and bacterial diseases that commonly affect orchids. It can also increase oxygen levels in stagnant water and potting media, preventing root rot. Used preventatively, diluted hydrogen peroxide may boost overall orchid health.

How does hydrogen peroxide work?

Hydrogen peroxide is made up of hydrogen and oxygen (H2O2). When diluted in water, hydrogen peroxide breaks down into water (H2O) and oxygen (O2). The extra free oxygen molecules released can increase oxygenation in the root zone, making the environment less hospitable to anaerobic bacteria and fungi.

The unstable oxygen radicals released during this breakdown can also directly oxidize and kill pathogens. Hydrogen peroxide essentially releases a surge of oxygen and oxidative molecules to blast away infections.

What diseases and problems can hydrogen peroxide help treat in orchids?

Here are some of the main uses of hydrogen peroxide for orchid health:

Fungal infections

Many different fungal diseases can infect orchids, such as fusarium, phytophthora, anthracnose, and orchid viruses spread by fungi. Fungal spores thrive in the low oxygen, humid environment of potting media. Diluted hydrogen peroxide can help gain control over fungal problems by raising oxygen levels. Hydrogen peroxide may also directly oxidize and kill fungal spores on contact.

Bacterial infections

Bacterial diseases like bacterial brown spot, soft rot, and bacterial blight can sometimes infect orchids, especially in overly moist conditions. The extra oxygen and oxidative burst created by diluted hydrogen peroxide solutions may help control bacterial pathogens.

Root rot

Root rot can quickly kill orchids by damaging their root systems. It is most often caused by overwatering, which allows fungus and bacteria to grow out of control in low oxygen, perpetually soggy media. Watering with diluted hydrogen peroxide instead of plain water can help orchids recover from root rot by oxygenating the roots and media.

Stagnant water

Letting orchids sit in stagnant water can encourage fungal and bacterial growth while starving the roots of oxygen. Watering with diluted hydrogen peroxide introduces much needed oxygen into pools of old water in saucers and pots.

How to use hydrogen peroxide on orchids

Here are some methods for using diluted hydrogen peroxide on orchids:


The most common way to use hydrogen peroxide on orchids is diluting it with regular water for watering. Here are some hydrogen peroxide concentrations and uses:

Hydrogen Peroxide Concentration Use
1-2 tsp 3% solution per gallon water General preventative care every 2-4 weeks
1 tbsp 3% solution per quart water Minor fungal/bacterial infections
1 tbsp 3% solution per pint water Moderate infections, root rot

Use the weaker concentration as a periodic preventative treatment. Use stronger concentrations to actively treat an existing infection.

Foliar spray

Mix 1 teaspoon 3% hydrogen peroxide per quart of water. Use this solution to gently mist the leaves, pseudobulbs, and air roots of orchids affected by bacterial or fungal leaf spot diseases. Spray every few days until the infection clears.

Root soaks

For orchids with severe root rot, soak the bare roots in a 3% hydrogen peroxide solution for 5-10 minutes to oxygenate the tissue before repotting into fresh media. This can help residual healthy roots recover.

Media drench

Heavily water pots with a 3% hydrogen peroxide solution to oxygenate old, dense media and kill pathogens. Let the solution drain freely from the bottom. Repeat every few weeks. This technique is useful for overwatered orchids prone to root rot.

When should hydrogen peroxide be used on orchids?

Hydrogen peroxide has many preventative and therapeutic uses. It can be applied:

  • When repotting, to clean roots and media
  • After overwatering, to oxygenate soil before root rot develops
  • To eliminate foul odors from media, indicating fungal growth
  • To treat early signs of fungal or bacterial disease
  • To revive orchids with severe root rot
  • Periodically as a booster for healthy roots and growth

Do not use hydrogen peroxide as agrowth stimulant fororchids more often than every 2-4 weeks, as overly frequent use can damage healthy root tissues.

Precautions when using hydrogen peroxide on orchids

Hydrogen peroxide solutions for plant care must be diluted to low concentrations like 1-3%. At higher concentrations, hydrogen peroxide can severely damage orchid roots and leaves. Follow these precautions:

  • Always dilute “3% hydrogen peroxide” from the drugstore before using on plants.
  • Do not exceed 3% concentration in the final solution.
  • Avoid getting hydrogen peroxide on orchid flowers and buds.
  • Use hydrogen peroxide solutions promptly after diluting, within a day or two at most. The oxygenating effects decrease over time.
  • Rinse off applications after 10-20 minutes to avoid burning delicate orchid tissue.

Signs of hydrogen peroxide damage

Hydrogen peroxide solutions that are too strong or left on too long can damage orchids. Watch for these signs of hydrogen peroxide burn:

  • Brown, dried out leaf tips
  • Root tip dieback
  • Wilting or desiccated leaves
  • Dead spots on leaves or pseudobulbs

If you notice these issues, flush the orchid thoroughly with plain water to prevent further burning. Be more cautious with hydrogen peroxide concentration and exposure time with future applications. Healthy orchid tissue can typically recover from mild hydrogen peroxide damage with time.

Alternative sanitizers

Some growers prefer to use other oxidizing agents besides hydrogen peroxide to oxygenate potting media, water, and disinfect diseased plants. Some alternatives include:

Physan 20

This broad spectrum disinfectant contains hydrogen dioxide along with detergent. It can help control fungi, bacteria, algae, and viruses on orchid foliage and flowers.


ZeroTol is based on hydrogen dioxide and peroxyacetic acid. It rapidly breaks down pathogens and inoculates growing media.

Vinegar or lemon juice

Diluted vinegar or lemon juice creates an acidic environment unfavorable to bacterial growth. These organic acids may also directly kill some fungi and bacteria. However, vinegar and lemon juice are less effective than hydrogen peroxide at oxygenating potting media.


Orchid growers previously recommended bleach solutions to disinfect diseased orchids. However, bleach harms beneficial microorganisms and can damage roots. Hydrogen peroxide is typically a safer option.


Some growers dust cinnamon on orchid wounds to deter fungus with its natural antiseptic compounds. Clinical evidence for its efficacy is limited.


Diluted solutions of household hydrogen peroxide offer an accessible way for orchid growers to increase oxygenation and battle diseases. Periodic preventative applications can enhance overall root health and growth. Hydrogen peroxide introduces needed oxygen to counteract the constant threat of root rot in orchid media. With proper precautions, hydrogen peroxide is a simple yet powerful tool for fighting fungal and bacterial problems. Integrating this common household item into your orchid care routine can significantly improve the health and longevity of your orchid collection.