arilate irises was bulb rant

Sat, 15 Nov 2014 15:50:07 PST

>In wet winter climates, "fast drainage" is very necessary to facilitate the
quick drying which other climates experience. In Britain we can experience
Spring, Summer, Autumn, and Winter in a 24 hour period.

And I bet that this requirement has been misappropriated for cultivation 
techniques in semi-arid and arid environments. (No, I don't bet; I know it 

Here's the Deno quote, from Seed Germination, Theory and Practice.
"It is appropriate hereto clarify one of the most pernicious misconceptions 
in the
horticultural literature, namely the subject of drainage. Growing roots are 
consuming oxygen. It is easy for them to be asphyxiated if the oxygen 
pressure is
reduced below the 0.2 atmospheres that is present in the air. The 
susceptibility varies
in different species. This subject is misunderstood to an incredible degree 
in the
horticulture literature. The word drainage is like a drumbeat punctuating 
paragraph. In fact a plant cannot possible care whether water drains fast or 
slow over
the roots. What is critical is the supply or more precisely the pressure of 
oxygen. The
word drainage should be crossed out throughout the horticultural literature 
replaced by the word aeration. The misunderstanding arose because media that
drain well usually are porous with 10-30% free air space so that they remain 
What has happened in the horticultural literature is that an aeration 
became misinterpreted as a drainage requirement. It can be added that if 
were essential, plants could never be grown by hydroponics."


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