If you sterilize
your own potting soil - or even if you have reason to
suspect potting soil you bought or already have - it is useful
to check to ensure that the potting soil is not toxic before
you go through the work and expense of planting your garden
using it. Fortunately, it is relatively easy to test, and
only takes a few days.
Place some potting
soil into a pot, and plant it with lettuce seeds (or other
seeds with a similar high germination rate), since they germinate
quickly, then watch to ensure that the seeds to germinate.
If the lettuce
does not begin to sprout within a few days, your soil is very
likely toxic and you should discard it or use it in your compost