a very large pot with a very small hole

Of course there are some tricks of perspective here - but nonetheless, this is a large pot - maybe the height of my elbow - one of two that had citrus trees in them (one lime, one Meyer lemon).  These fruit trees were doing - well, not brilliantly, but were ok, until our gardener decided that the rosemary and oregano that was also in them needed to come out, since they were sapping energy from around the roots, and the trees needed repotting in special citrus compost.

This didn't work.  Somehow, the pots then didn't drain at all - we think their tiny, inadequate drainage holes must have been flat against the ground, and over time, and some really drenching rains, the water has been an inch or so deep at the top, forming swimming pools for bees.  The trees hated this; their leaves started turning yellow and dropping.  This is not the California dream ... So now the trees are planted in the ground; the pots will be raised off the ground on bricks, and, once the spread-out soil has dried out, planted with bay trees and trailing rosemary.  Keep your green fingers crossed.