It's a good idea to wet your potting soil first, wet enough that it can be
formed into a soft ball when squeezed. It should be moist but not soaking
wet. If you do this first, you should find that the water will then drain
through. If not, you need to lighten your soil by using perlite. Make sure
that you have a drainage area in the bottom of the pot.
Hope this helps.
--
gloria - only the iguanas know for sure