Trees, Shrubs and Conifers: quickly declining barberry red rocket? , 5 by kinym

kinym wrote:
It was purchased a month ago, planted in a rock garden type setting. Light watering and a small bit of rain. Warm weather, 70's and just reached the 80's this week. It stayed bright red for about 3 weeks, then slowly began turning more green, with some not all leaves curling, dry at the tips, some whole branches dry. I'm adding pictures of before and after... Does anyone know what could be going wrong? I pulled it out to check the roots. New roots look bright yellow green, and the soil, football was just damp, not soggy. I checked the drainage of the hole, filled it with water and it drained in less than 5 minutes. We had some very windy (40 plus mph) days since it was planted. I can't figure out the problem. Any help would be appreciated thanks!