Soil-less Potting Mixes

David W. Kramer kramer.8 at OSU.EDU
Thu Mar 11 14:32:24 EST 1999

Greetings, Charles!
Good to hear from you!  How's everything at St. Olaf's?  I have only a
small greenhouse here at the Mansfield campus, only large enough to
maintain experiments for our introductory classes.  For all those
experiments we use Pro-Mix and are very pleased with it.  It comes
compressed and dried in bales wrapped in plastic.  In that form it is very
easy to store.  It is mostly peat and perlite.  It has little or no
fertilizer but I like that because we can use it depleted for some
experiments or add fertilizer for others.  It comes sterilized and we have
had no problems with soil-borne disease.  One needs to add water before
planting in it.

If you wanted to use it for plants to be maintained for long periods of
time, i.e.,  a "teaching collection", you probably would want to add some
top soil.  We add sand to Pro-Mix (1:1) to use it as a medium for
propagation of stem cuttings of mums for an experiment (with and without
Rootone).  I don't maintain a teaching collection in our greenhouse because
it isn't large enough and also because we are lucky to have Kingwood Center
here in Mansfield that has a wonderful conservatory and outdoor gardens
that are open to our classes (and to the general public) free of charge.  I
just tell my students (all are commuter students) that "our class will meet
at Kingwood for lab this afternoon."  It's quite an asset to our program.

Best regards!  Good luck!

Dave Kramer

>My students and I are in midst of annual repotting of our collection.
>We use a soil-based mix but are finding it increasingly difficult --
>and expensive -- to find sterilized soil.
>I've seen a lot of soil-less mixes in the greenhouse/horticultural
>supply catalogs.  I was wondering what peoples experiences have been
>with these mixes for tropicals? temperates? succulents and cacti?
>Charles Umbanhowar
>Dept of Biology
>St. Olaf College
>Northfield, MN 55057
>ceumb at

David W. Kramer, Ph.D.
Asst. Prof. of Evolution, Ecology, and Organismal Biology
Ohio State University at Mansfield
1680 University Drive
Mansfield, OH  44906-1547
Phone:  (419) 755-4344      FAX:  (419) 755-4367
e-mail:  kramer.8 at

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