|I'm looking for an evergreen shrub which will grow to about 18|
|Dwarf Italian Cypress (Cupressus sempervirens 'Tiny Tower') has dense blue-green foliage and maintains its narrow, columnar form and tidy, well-groomed appearance without pruning. It is well suited to topiaries and containers and is slow growing to 10 to 15 feet tall. Or, you might consider Thuja occidentalis 'Holmstrup' is an upright, compact, conical conifer, growing 7 feet tall and three feet wide.
Best wishes with your landscape!