Peroxide for Overwatered Plants

Root Rot

• Root rot is a dangerous condition that occurs in both houseplants and those grown outdoors. A variety of fungi cause it, and although overwatering is not always to blame, it often is. When roots are inundated with moisture, they begin to die off and drown, and various fungi move in to take advantage. The best way to prevent root rot is to avoid overwatering and ensure adequate drainage, but if it’s too late for that, hydrogen peroxide can help you nurse a plant back to health.

Using Hydrogen Peroxide

• One of the reasons roots die off when overwatered is that they can no longer access oxygen under such conditions. Hydrogen peroxide solves that by continuing to supply the plant with moisture as well as oxygen. When H2O2 enters the soil, one of its oxygen atoms breaks off, resulting in water molecules (H2O) and free oxygen. This can help the plant get the oxygen it needs. In hydroponic systems, growth in a pure water environment can also limit oxygen, so adding in some hydrogen peroxide can help balance out the environment.

Precautions

• In both container plants and plants growing in the ground, as well as hydroponic environments, you must make sure not to shock the plant with too great a dose of hydrogen peroxide. It can be quite caustic, especially at higher concentrations, so wear gloves when dealing with it and quickly wipe up spills. Buy 35 percent food-grade hydrogen peroxide, and dilute it to 3 percent by mixing in a solution of 1 part H2O2 and 11 parts H2O. You can safely pour this on plants potted in soil or growing media. In aqueous environments, ensure the hydrogen peroxide does not exceed 3 percent as well.

Other Uses

• In addition to its uses as a water replacement while plants recover from rot, hydrogen peroxide works as a fungicide. When poured over the soil, it will not hurt the plant -- provided you have diluted it correctly -- and will kill off unwanted soil fungi and bacteria, which may harm it. You can also use it as a disinfectant when repotting or reusing a pot that has previously harbored disease.