Putting Bits of broken terracotta pots at the bottom of plant pots to improve drainageby Malcolm Greenhalgh on 03/28/13
My grandfarther, who started me off gardening over fifity years ago, taught me always to put bits of broken pot at the bottom of plant pots so that excess water will drain away quickly. Recent research, however has shown that this is not only unnecassery, but that there are far better ways of going about it. Apparentely those bits of pot do not aid darinage; instead they create what soil-water scientists call a "perched water table". In other words, the crooks do not enhance drainage, but they hinder it.
What they suggest as a far better approach is to mix plently of grit into the potting compost (since I read about this I have been putting one unit of grit to nine units of Sinclair, Clover or other non- soil compost .. it seems about right). I compared this with a large pot containing crock at the bottom and with pure Sinclair compost on top, and found that drainage greatly improved and that the compost was not so heavy and stodgy (i.e there was more air in the compost, and plant roots need lots of oxygen). Of course, with no crocks the plant also has more compost for its roots to penetrate. the grit we sell at the Hut is ideal.