Are purple leaf plum hedge plants evergreen?

Yes, purple leaf plum hedge plants are evergreen. The woody plant in question (Prunus cisterna) does not drop its foliage within less than a year, which is the hallmark of deciduous or non-evergreen plants. Purple leaf plum hedges provide landscaping color, interest, and texture even while other plants that do not drop foliage over the course of several years are littering the ground with leaves for composting.