On Fri, 25 Apr 2014 15:04:43 +0100, Nick Maclaren wrote:

This article from last year by biologist Ken Thompson is on the same
theme:
http://www.telegraph.co.uk/gardening...ing-crocks-to-
help-containers-drain-A-potty-idea.html

It is they who are potty. Older pots had quite large holes, and the
soil loss could be considerable - indeed, if it were a sandy mix, it
could be near-total. Also, if used judiciously, a bit of curved broken
pot can increase the effective size of small holes.

The whole thing about a perched water table is on target though. But
certainly, if you use terracotta pots you need something (a bit of crock)
to keep the soil in. I don't; in plastic pots ranging from 7x7x7 to 35 l
(quite large) I use very free draining, practically soil-less mix, with
no crocks.

-E

--
Gardening in Lower Normandy