American Pillar ArborvitaeNeed the height of the ever popular 'Green Giant' but don't want to take up width in an already size constrained space? Enter 'American Pillar' Arborvitae, which matures at only 5 6' wide and is a fantastic option for the smaller suburban landscape. Handsome green foliage remains year round and provides privacy as a screen or as a narrow growing specimen planted alone.