gethyllis cold tolerance (Rick Buell)

Tim Eck teck11@embarqmail.com
Fri, 23 Jan 2015 06:36:56 PST
One way to envision this boundary effect:
If you have identically sized spheres their closest packing is about 74%,
leaving about 26% voids.  If you then place much smaller spheres in contact
(think gravel and sand), the sand will infiltrate the gravel voids, taking
up 74% of this 26% =19%.  So, now the contact zone is 93% solid and 7% void.

Tim


-----Original Message-----
From: pbs [mailto:pbs-bounces@lists.ibiblio.org] On Behalf Of Alberto
Sent: Friday, January 23, 2015 8:51 AM
To: Pacific Bulb Society
Subject: Re: [pbs] gethyllis cold tolerance (Rick Buell)

Putting ingredients of  a potting mix in layers slow down drainage instead
of improving it. This has been researched for long. Water will percolate by
gravity through a layer but when reaching the next it will collect making
the mix stay wet for longer than planned through capillarity. This s the
reason why the best potting mixes are a combination of not water retaining
materials, so excess water is rapidly forced out. 

 		 	   		  





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