"*Boxwood 'Dee Runk' is reportedly the nicest of the columnar boxwoods tolerating shade and clay soils. Total height of ft tall can be sheared shorter. Max width about two feet. Advantage over other upright boxwoods is dense growth that won't flop open.
Check out 44 Best Shrubs for Containers. You might know some plants and some may surprise you but one thing is sure- Youll like to have some of these shrubs right away in your container garden. - New Gardening Ideas
A stunning evergreen shrub to place at the back of your garden bed is the Castle Wall™ Blue Holly. Growing to an impressive 5 to tall, but only 3 to this holly is perfect for mid-sized gardens as it’s narrow, pyramidal shape won’t overwhelm - Picmia