Fall planting of perennials is really important in the Gulf Coast in order to give the plants plenty of time to develop their root structure. I find it really annoying to see perennials showing up in garden centers too late in spring for them to really get established before our hot weather hits. Big Box stores are particularly bad about this. Local nurseries tend to get these plants out earlier, if not always in the fall. They need to be encouraged. In the Houston area, November/December are ideal planting months for most perennials, trees, and shrubs.