Plant 'American Pillar' Arborvitae in well-drained soil with full sun to partial shade. Space plants 3-4 feet apart for optimal growth. Water regularly, especially during the first growing season, to establish a deep root system. Fertilize in early spring with a balanced, slow-release fertilizer. Prune lightly to maintain desired shape and remove any dead or damaged branches. Protect from harsh winter winds and heavy snow by wrapping with burlap if necessary.