Hydrogen peroxide can be used for- pest control, treating root rot pre-treating seeds foliar spray to kill fungus infection preventive on damaged trees While it has also been used as a general “fertilizer” either added in during watering or sprayed onto the foliage, hydrogen peroxide is not a fertilizer, but it can help boost plant growth.Hydrogen peroxide helps encourage healthy root growth because of the extra oxygen molecule. Oxygen can help plant roots absorb nutrients from the soil. Therefore, this extra bit of oxygen better enables the roots to absorb more nutrients, which means faster, healthier, and more vigorous growth. As an added bonus, hydrogen peroxide can help discourage unwanted bacteria/fungi that may be lurking in the garden.