The hydrogen peroxide in rainwater that makes it more effective than tap water when given to plants. With the increased levels of atmospheric pollution, however, greater amounts of H202 react with air-borne toxins and never reach the ground. To compensate for this, many farmers have been increasing crop yields by spraying them with diluted hydrogen peroxide (5 to 16 ounces of 35% mixed with 20 gallons of water per acre). You can achieve the same beneficial effect with your house plants by adding 1 ounce of 3% hydrogen peroxide (or 16 drops of 35% solution) to every quart of water you give your plants.
It can also be used as a safe insecticide.
Spray plants with 8 ounces of 3% peroxide mixed with 8 ounces of white sugar and one gallon of water.