Soil sterilisation is an important chore that every gardener should be doing. It consists of killing plant pathogens and weed seeds. All soils should go through this process especially if the soil is from the garden or from an old bag of potting soil. Make sure to only sterilise what is going to be needed in the near future or store sterilised soil in a tightly closed container. If this is not done, the soil will need to be re-sterilised to kill any contaminants.
Preheat the oven to 82.2 degrees Celsius.
Collect containers that are going to be used for the soil sterilisation. Fill containers with 4 inches of garden or potting soil. Smooth the surface of the soil so it is even in the containers.
Cover each container with aluminium foil. Crimp the edges of the foil all the way so a tight seal is formed.
Poke a meat thermometer through the foil into the soil in the centre of the container.
Once the oven has reached 82.2 degrees C, place containers in the oven.
Heat soil until it reaches 82.2 degrees C. Once this temperature is reached, time the soil for 30 minutes.
Turn off the oven and open the door. Let containers completely cool before removing them from the oven.
Store soil in the containers until it's needed or remove it from the containers and place it in plastic, sealable bags that have been labelled.
Heated soil gives off an odour, so do not remove the foil until it's ready to use. Do not let soil go above 93.3 degrees C. When this happens, plant toxins are released into the air and contaminate the soil.