Arborvitae occidentalis 'Emerald Green' (= 'Smaragd') 

Slow growing, narrowly pyramidal evergreen, reaches 10-15' tall, but only 3-4'wide. Lustrous emerald green foliage both summer and winter. Useful as a narrow hedge or as a backdrop. Excellent heat tolerance.

Full sun or light shade in rich, moist, well-drained soil. Best sited out of severe winter winds.

Emerald Green Eastern Arborvitae