Question
I have a princess flower tree that I planted almost a year ago, in a half wine barrel in my backyard (I live in the S.F. east bay area, specifically castro valley).  It is looking slightly unhealthy: it's leaves are not a very vivid green, and while there are plenty of flower buds, the flowers are not opening completely, they are just shriveling up as soon as they bloom. My back yard can get very hot (high 80's - 90's, rarely reaches 100) and the sun is intense, but the tree gets shade in the morning.  I've been watering it daily when it's very hot, and every other day when it's less hot.  Can I be overwatering it?  Or can it be having a difficult time in the heat?

Answer
I think you are over watering it. A tree needs about 1-2 inches of water each week. When you water put a pan under the tree and when the pan has 1 inch of water stop. Do this once a week. Too mch water for a tree in a Pot will rot the roots so I would back off the water.