Place two pounds
of potting soil into a thick plastic bag (such as a freezer
bag, not a thin "sandwich" type bag which can melt
in the microwave. Place bag in microwave leaving the top open
for ventilation. Microwave on high for two and a half minutes
on high. Remove from microwave promptly and seal top. Allow
to sit until cool, then use. You an keep the soil in the bag
with the top closed for storing.
This method will
not smell your house up quite as much as the oven method,
but you can only sterilize smaller portions of potting soil
ast a time. Remember, do not heat for longer that two and
a half minutes or you can make the soil toxic.