The redbud tree has been in that location for about six years. It had beautiful, but slightly sparce, displays for the first few years.

In the spring of 08 it didn't bloom at all.

We are in a severe drought. Somebody said that the buds are set in the fall, so I've been pouring on copious amounts of water since last summer.

Now it is blooming a bit, but not as much as others in this area. Could it be that redbuds need a cold winter?

In general redbud should be fine in Texas - there is a form of it that is native to parts of Texas.