Weeds, fungi, diseases and other unwanted pathogens in previously used potting soil can harm your container plants in the next growing season. Many living things in the garden soil are actually beneficial for your container plants, including bacteria, fungi, worms, insects and more. These living things break down nutrients in the soil so plants are able to use them. But in addition to beneficial living things, some diseases and pathogens can live in your soil for a long time, waiting around until they can infect your next batch of crops.
Consider sterilizing your garden soil in order to keep harmful pathogens from infecting your next plants. This is especially important in soil that has contained plants that you know are diseased. Some diseases, such as fungus that affects potatoes and tomatoes, can infect soil for years and should not be used unless the soil is sterilized. For starting seeds, growing delicate plants and for growing crops in soil that previously held diseased plants, you will want to use sterile soil to reduce the chances of infecting your new container plants. Sterilizing soil is easy. Just follow these easy steps:
1. Preheat your oven to 200 degrees.
2. Put the soil in an oven roasting bag, add water and tie the bag.
3. Poke a hole in the top of the bag so you can put a meat thermometer in the bag.
4. Put the soil bag on a pan in the oven and heat it until the meat thermometer reads 160 to 170 degrees.
5. Let the soil “cook” for 30 minutes after reaching 160 to 170 degrees.
6. Remove the bag from the oven and let the potting soil cool.
Once your potting soil has “cooked,” the harmful pathogens will be killed off. Now your sterilized soil is ready to use!