How to Sterilize Soil for Potting


If you are tempted to save money by using dirt from your garden as potting soil, instead of purchasing sterile potting mix at the gardening center, it may not be a bargain. Soil fresh from the backyard doesn't drain as well as potting mix, and it typically contains weed seeds. One solution is to make your own potting soil by combining equal parts compost, perlite and peat moss. After making the potting mixture, sterilize the soil at home to help prevent plant disease.

Step 1

Heat the oven to 250 degrees F.

Step 2

Spray the soil with water to moisten.

Step 3

Fill a heat resistant pan with the moist soil, no more than 4 inches deep.

Step 4

Cover the pan with aluminum foil.

Step 5

Insert an oven meat thermometer into the center of the soil, through the foil, so that you can read the gauge.

Step 6

Place the pan in an oven at 250 degrees F. Heat the soil to 180 degrees F, keeping it at that temperature for 30 minutes. Do not allow the temperature to exceed 200 degrees F. Allow the soil to cool before using.

Things You'll Need

  • Soil
  • Spray water bottle
  • Heat resistant pan
  • Aluminum foil
  • Oven meat thermometer


  • Oregon State University: Make your own Potting Soil
  • CSU/Denver County Extension Master Gardener: Start Seed and Transplants in Sterilized Soil
Keywords: sterilizing soil, pasteurizing soil, sterilizing soil oven

About this Author

Ann Johnson has been a freelance writer since 1995. She previously served as the editor of a community magazine in Southern California and was also an active real estate agent, specializing in commercial and residential properties. She has a Bachelor of Arts in communications from California State University of Fullerton.