Houston is a hard place to plant. It is not just the heat — it is heat plus humidity plus heavy clay that drains slowly, and then a hard freeze every few winters to remove anything that got comfortable. Plants that thrive in a dry heat can rot here, and plants that handle wet feet can cook.
The reliable performers earn their place by handling all of it. Dwarf yaupon and Texas sage take the sun and the drought without complaint. Loropetalum brings colour without needing constant attention. Muhly grass looks like nothing for most of the year and then carries a whole bed in the fall. For colour that keeps going through the worst of it, lantana and salvia are hard to beat.
The shade side is where people struggle, particularly under the mature oaks in the Heights and the pines up north. Turf will not fill in there no matter how much is spent on it. Holly ferns, cast iron plant, and liriope will, and they stop the annual cycle of reseeding grass that was never going to take.
How you plant matters as much as what you plant. In clay, dig the hole two to three times as wide as the root ball but no deeper, amend the backfill, and set the crown slightly above grade so water moves away from it rather than pooling around the stem. A plant put in badly will struggle for years; the same plant put in well is essentially self-sufficient after the first season.
Then water deeply and infrequently rather than a little every day. Light daily watering keeps roots shallow, which is exactly what you do not want going into August. Six weeks of proper establishment watering buys you a plant that can look after itself through the summer.