Homemade Soil Sterilizers

Written by mindy mcintosh-shetter
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Homemade Soil Sterilizers
Soil needs to be sterilised before planting. (Jupiterimages/liquidlibrary/Getty Images)

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.

Skill level:

Things you need

  • Oven
  • Non-plastic containers such as clay pots, metal or glass pans 5 inches high
  • Garden or potting soil
  • Hand spade or shovel
  • 1 roll of aluminium foil
  • Meat thermometer for each container used
  • Oven gloves
  • Resealable plastic bag, optional
  • Marker

Show MoreHide


  1. 1

    Preheat the oven to 82.2 degrees Celsius.

    Homemade Soil Sterilizers
    A typical household oven not only bakes pies but also soil. (oven temperature control in red image by laurent dambies from Fotolia.com)
  2. 2

    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.

    Homemade Soil Sterilizers
    Containers that are used for soil sterilisation should only be used for this purpose. (the form for an oven image by Leonid Nyshko from Fotolia.com)
  3. 3

    Cover each container with aluminium foil. Crimp the edges of the foil all the way so a tight seal is formed.

    Homemade Soil Sterilizers
    A little extra aluminium foil will be needed to seal the container. (aluminium foil image by Andrey Zyk from Fotolia.com)
  4. 4

    Poke a meat thermometer through the foil into the soil in the centre of the container.

    Homemade Soil Sterilizers
    A meat thermometer is needed for each container. (meat thermometer image by Kimberly Reinick from Fotolia.com)
  5. 5

    Once the oven has reached 82.2 degrees C, place containers in the oven.

    Homemade Soil Sterilizers
    Using pans of the same size will allow even heating. (pots pans and barn 1 image by Lise Powell from Fotolia.com)
  6. 6

    Heat soil until it reaches 82.2 degrees C. Once this temperature is reached, time the soil for 30 minutes.

    Homemade Soil Sterilizers
    Check on the soil temperature often to prevent the temperature from going above 93.3 degrees C. (timer image by Lombok from Fotolia.com)
  7. 7

    Turn off the oven and open the door. Let containers completely cool before removing them from the oven.

    Homemade Soil Sterilizers
    Only handle the containers with oven gloves when removing them from the oven. (tray of fresh baked chocolate chip cookies image by nextrecord from Fotolia.com)
  8. 8

    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.

    Homemade Soil Sterilizers
    When storing the sterilised soil, make sure to mark the container. (marker image by Rich Johnson from Fotolia.com)

Tips and warnings

  • 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.

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