H2O2, or hydrogen peroxide, is known for its sterilizing and cleaning properties. But it can also release oxygen that makes it an effective tool to combat root rot. Roots require oxygen to breathe, and when they are over-watered or planted in soil with poor drainage, they develop root rot. When you water your plants with H202, it releases oxygen into the soil around the roots so that they can breathe again.
Fill your watering can with half H202 and half water.
Add an anti-fungicide like benomyl (follow the manufacturer's instructions for the amount of water that you are using).
Add a fertilizer with rooting hormone like Root Booster to the soil (follow the manufacturer's instructions for the amount of water that you are using).
Water the plant heavily with the H202 solution. Do not stop until water comes pouring out of the drainage holes in the pot. Then empty the drainage tray. Do not water the plant again until the top two inches of the soil are dry.
Continue to water your plants as usual, using a solution that is half peroxide and half water.
Discontinue using the peroxide solution when your plants perk back up.