A lot of patio pots are sold without drainage holes so that the buyer can either use the pot as a jardinière -- putting a functional, non-decorative pot inside -- or drill holes for direct planting. I found that with pots that are going to sit directly on a deck or patio it's best to drill the holes on the side of the pot, 1/2"-1" from the bottom, rather than the bottom of the pot. That way your pot will drain and won't form a seal with the flat surface.
