Growing medium

Thu, 12 Jul 2012 12:17:15 PDT
Agreed with Nhu on pumice, it has been a staple ingredient for my plants
for years. However, I ran into some problems with the finer grade
(Dry-stall) after using it over 1-2 seasons on a wide range of plants. The
particles are finer, something like Grape Nuts cereal, and in combination
with the 'fines' that are always present they formed a dense mass that was
less aerated than what some of my bulbs wanted. This is in contrast to
"regular" pumice with particles about 3x larger, which has never presented
such problems. Some finer-rooted bulbs (Lachenalia, etc.) grew well with
Dry-stall while others did not.

Structurally, the key to a suitable mix is to have particles of different
sizes that come together after a few waterings to provide space for air and
roots and also provide a natural firmness. Soil firmness is often
overlooked and is very important in keeping roots happy. Potting and
watering techniques are important also, but finding the right combination
of-- in my case-- pumice, sometimes perlite, sand and organics is critical
to success in terms of physical structure.

Dyla Hannon


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