This limits root growth which, in turn, creates stress for the tree. Trees become root-bound, often girdling themselves and choking to death. Roots cannot tolerate extreme changes in temperature. Soil temperature below ground stays relatively stable. It's warmer in winter and cooler in summer than soil in above-ground containers.
Insulated containers are better able to withstand extreme temperatures.
They cannot survive on rainfall alone. Often, containers do not provide adequate drainage, which means that roots can become waterlogged and the tree can drown. Make sure containers have drainage holes. Nevertheless, expect to replace containerized trees every two to five years. The flowers, ranging from white to pink, are fragrant.