How to Fix Root Rot

Preparation
1. Remove the affected plant from the plant pot and set aside. Remove all other plants from the soil, because it is contaminated and will need to be replaced. Set the plant with root rot aside, away from the other plants.
2. Rinse the roots of the healthy plants in 75-degree water to remove the existing soil.
3. Mix sterilized drainage material like rocks, gravel or broken pieces of clay pot into your sterile soil to improve drainage. If you are using a container to grow your plants, put 2 to 3 inches of drainage material on the bottom of the pot to improve soil drainage.
4. Fill the container or growing area half full of soil and drainage mix. Gently place the plant in the planting area and hold it in place as you gently fill soil around its roots. Once the plant is stabilized and the growing container is full to within 1 to 2 inches of the top, give the soil a little pat to gently pack it in and even it out.
5. Water your newly replanted plant liberally and watch the water drain to make sure that its stagnant, root-rot encouraging water is no longer stopped up in your growing area.
Sterilizing soil
6. Sterilize the new soil. Preheat the oven to 200 degrees.
7. Place the soil in an oven bag like that which you would use to bake turkey and add a cup or two or water until the soil is moist, not runny. Seal the oven bag. Poke a meat thermometer into the soil at least 2 inches deep to measure the temperature.
8. Bake the soil at 200 degrees until the soil has been at 170 degrees for 30 minutes. If the soil begins to exceed 170 degrees before the time is up, turn the oven down or temporarily off to adjust the temperature.
9. Turn the oven off and allow the soil to cool inside the oven until it reaches a safe handling temperature; typically 110 degrees or below. The soil will be hot enough to burn you until it has been allowed to cool to this point.
10. Remove the soil from the oven and allow it to cool to room temperature before using it.