- 1). Purchase 35 percent food-grade hydrogen peroxide. The kind commonly found at drug stores (three percent) often has additional chemicals and should not be given to plants. Thirty-five percent hydrogen peroxide is available at hydroponics supply stores.
- 2). Add 2 tsp. of peroxide per gallon of water for potted plants. Add 1/2 tsp. of peroxide to a spray bottle full of water for spraying leaves. Double these amounts and spray on plants to treat fungal infections or moldy soil. Stir the water and peroxide mixture with a wooden spoon or stick.
- 3). Water your garden and lawn with peroxide using a fertilizer spray attachment on your hose. Add 6 tbsp. plus 2 tsp. of peroxide and fill the rest of the attachment with water for a 10-gallon spray attachment. Use 3/4 cup of peroxide in a 20-gallon spray attachment.
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