Arborvitae (Thuja occidentalis) - mature width, plant 3 to 4 feet apart. Measure the height and width of the largest root ball. Then use spray paint to mark out a trench that is two to three times wider and 2 inches shallower than the root ball.
In Seaver and Speck's backyard, landscape architect Tessier had the idea to add six African sumac trees to shade an elegant outdoor dining room. He left enough space for a vegetable garden and a bit of lawn for the clients' young daughter.