From: klier@iscsvax.uni.edu
Subject: Re: Potting soil without earth?
Date: 12 Aug 93 15:35:26 -0600

ab419@Freenet.carleton.ca, Andre Jutras writes:

> I'm having a hard time finding good potting soil to use for
> repotting two Bonsai plants (Juniper, Boxwood). It seems that
> everything that is sold commercially as potting soil is made of
> shredded decayed tree stumps or something like that. Maybe I'm wrong
> and there has been new developments in potting soil that I dont know
> of. Can anyone tell me if these two plants can be potted in what is
> currently sold as potting soil? I was tempted to just dig out behind
> a farmer's field and use good garden earth.  Why cant you buy garden
> earth as potting soil?  --

Sounds like you're looking at stuff like Metro-Mix, Jiffy-Mix,
Redi-Earth...  which I've never had a whole lot of luck with.  You
don't want to use plain soil (even good garden loam) because the soil
packs together too much, and the roots can't get air properly (that's
one of the many functions of earthworms and other burrowing critters
outside: they keep the soil full of airspace).

My old all-purpose greenhouse mix is equal parts of sand (the sharp
beige stuff used for sandboxes, not fine quartz or coral sand from the
beach), finely chopped sphagnum, and good black dirt.  Sterilize
before use.  You can vary the composition to suit the plants (e.g.,
more sphagnum for something that needs lots of water, more sand for
succulents).

The stuff I see sold as "potting soil" around here at K-Mart/Walmart
type places is basically compost, and seems too "pack-downy" to me.  I
add healthy amounts of perlite or sand to it before use.  The "Sam's
Choice Potting Soil" at Walmart is a cut above the regular stuff, and
mostly usable as is.

Kay Klier  Biology Dept  UNI