How much water?

Husband driving me nuts over watering the pot plants or rather not watering them enough. I was always taugtht that you water well i.e. until water starts to drain out of the bottom of the pot. We have a load of lovely new bedding plants and he sort of just 'dusts' them with water, for the life of me I cannot understand why. Advice please lovely gardening people on how to cure this before we lose all the new bedding plants.