Growing medium
Rodger Whitlock (Wed, 11 Jul 2012 17:01:07 PDT)

On 11 Jul 2012, at 8:49, Bulborum Botanicum wrote:

I can tell you how the City of Victoria used to sterilize potting soil: on a
large concrete pad, they'd lay out lines of 6" drain tiles (probably terra
cotta), pile the soil over those, then pass steam through the lines until the
entire pile was steaming.

This wasn't sterilization in the strict sense. It's really pasteurization,
killing off most seeds, pests, and microbes, but leaving some microbes alive.

I suspect, but can't say for sure, that they mixed John Innes type potting and
seed composts where the additives (lime, fertilizers) went in *after* the soil
had been pasteurized.

A simpler system for smaller quantities: put your damp soil in black plastic
garbage bags and leave them in the sun.

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