Penta's are tropical plants from Hawaii and need lots of water if you want to grow them in the hot Texas sun. They also need good drainage. If the plants are in pots they could be drying out or staying too wet if the pots sit in drainage water. If you let them dry out they will really look bad for awhile but may recover. If all the plants are dying it could be you had a touch of frost or cold night or is it possible some herbicide spray landed on them? Maybe chlorine pool water? Perhaps you can send a photo and I will be more of a help solving this mystery. Keep growing, Marianne Binetti