Q.My bougainvillea bush
My Bougainvillea bush got hit with frost in Houston and it is totally brown. I would hate to lose it. What can I do or is it a lost cause? It’s pretty big.
Wait until after the danger of more frost has passed. The damaged parts of the plant actually may help insulate the plant.
When the danger of cold and frost has passed you should trim the plant back to healthy parts of the vine, making sure you cut a leaf node.
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/pruning-bougainvilleas.htm
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-winter-care.htm