shootersm, Although the gritty mix drains well, so the roots don't rot from wet soil, it retains moisture well. Stays damp for a long time, plus it's got air which the roots need too. You don't need to water as much, but now and then is fine.
Get yourself a little water meter or something called a soil sleuth. I love my soil sleuth. You just insert it deeply into the soil, give it a twist, and the soil catches in it's notches. When you pull it out you can see exactly just how damp or dry the soil is. If you are handy, you can just notch a dowel and do the same thing.
Suzi