I have a concrete planter (round cup-shaped top, stem, square base. Urn-like, I guess), that doesn't have a drain hole. Is it possible or feasible to drill a drain hole from the bottom of the "cup" through the stem, and out the bottom of the base? It might be 7" or so. Will it crack the concrete? Any other ideas? Thanks!
P.S. We really need some type of drainage, as the flowers are stunted and a heavy rain just filled the bowl!