How to Use Potting Soil From a Previous Year

Avid gardeners generally have pots and raised beds full of used potting soil. Reusing it saves money, but it can also kill your seeds or plants unless it is sterilized to remove pathogens that can cause diseases such as damping off. Used potting soil also harbors pests. Several methods are available to the home gardener to sterilize used potting soil, and using the oven is the most common.

Shallow baking pan
Aluminum foil
Meat thermometer

Instructions

- 1
  Preheat the oven to 180 degrees Fahrenheit.
- 2
  Fill a shallow baking pan with 4 inches of barely moist soil. Cover the pan with aluminum foil. Insert the meat thermometer through the foil and halfway through the soil. Do not allow the thermometer to touch the sides or bottom of the pan or you may get a false reading.
- 3
  Place the pan in the oven. When the meat thermometer reads 180 degrees Fahrenheit, set a timer for 30 minutes. The soil temperature must not drop below 180 degrees during this time.
- 4
  Remove the pan from the oven and set it aside to cool completely.

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