I think there is a Texas gardening forum. I don't know how much traffic there is but you might get some good suggestions there. Here it is: gardening in Texas

Some info you might want to add, either here or on the Texas forum:

Photo? This gives us info on bed size, window height and spacing, eaves and gutters, etc. Are there overhanging trees or is this bright shade?

What part of TX (nearest big city)? I think there's a fair variety of moisture and temperature regimes since it's such a big state. How many months do you have without frost?

Goals? Year round interest, flowers for cutting, butterflies and/or hummingbirds, scent, etc.?

All good suggestions/questions from the posters above. I'm in southern New England so my north side is definitely much cooler than where you are. It's on the north side of my house and provides full shade so I designed and planted a full shade bed that included various "designer" hostas as well as other shade lovers including Carex/Japanese forest grass 'Ice Dance,' Brunnera/Siberian bugloss, Dicentra/Bleeding Heart, Astilbe & Pulmonaria/lungwort. At the eastern edge that gets a bit of sun I planted Hellebore/Lenten roses; they bloom in February/March (even here in the frozen north) and the blooms last for 6+ weeks.