Last summer, I ran into the problem with some of my potted plants which seemed to dry out way to fast under full sun, especially the ones that have well established plants. It seems like the soil looses it's capacity to hold any water when the roots take over the pot so one of my solutions to lessen the problem is mixing in water absorption crystals to the soil.
These crystals can carry 400 times their own weight in water, and they are supposed to last for multiple seasons, and they are supposed to be soaked in water before they are put into the pots to work best.
Here's the bags that they come in. I puchased 5lbs of this stuff so it should have the capacity to hold 2000lbs of water which should last me a while.
