On never reusing potting soil
Rodger Whitlock (Thu, 07 Feb 2013 14:55:41 PST)

Try throwing spent potting soil, esp. that from seed pots, onto some more-or-
less waste area where strays and interlopers won't matter.

Bob Woodward and Jim MacPhail used to toss their old seed pot contents on a
grassy slope in front of their house, and ended up with a marvelous planting of
all sorts of things that decided to germinate once thrown away. Spent soil from
pots of geophytes will behave similarly because you invariably miss a few small
offsets when repotting.

This is called making lemonade from lemons.

--
Rodger Whitlock
Victoria, British Columbia, Canada
Z. 7-8, cool Mediterranean climate