Sterilizing Dirt for Seed Starting

Preheat your oven to between 180 and 200 degrees Fahrenheit. Spread soil evenly into a nonplastic container, such as a glass or metal baking pan or a clay pot, and insert a meat thermometer into its center. Do not allow the soil to exceed 4 inches in depth. Cover the container with aluminum foil and place it in the oven. Bake the soil until it reaches an internal temperature of between 180 degrees and 200 degrees Fahrenheit; allow the soil to bake at this temperature for at least 30 minutes. Remove from the oven and allow to cool.

Place soil in a nonmetal container, such as a glass baking dish. Cover with foil and microwave on full power for 90 seconds per 2.2 pounds of soil.

Place a wire rack in a pressure cooker. Pour several cups of water into the cooker until the water level is roughly 1/2 inch below the wire rack. Fill a shallow pan, such as a small glass baking dish, evenly with soil, but do not allow the soil to exceed 4 inches in depth. Cover the container with aluminum foil. Close the pressure cooker lid, leaving the steam valve open. When steam begins to escape from the valve, close it and heat at 10 pounds pressure for 15 minutes. Turn off the heat, wait until the container cools and remove.

Preheat your oven to 200 degrees Fahrenheit. Add soil and 1 to 4 cups of water to an oven roasting bag and tie the bag closed. Poke a hole in the bag with a meat thermometer and insert the thermometer into the center of the soil. Place the bag on a shallow metal or glass baking dish and put it into the oven. Use the meat thermometer to check the internal soil temperature, allowing the soil to heat to between 160 and 170 degrees Fahrenheit. Leave the soil at this temperature for 30 minutes. Remove the soil and allow it to cool.