In general, a perennial takes two or three years after planting to shine and a ground cover about the same time to fill in. A small shrub may wait four years to fulfill its promise. A large shrub or small tree needs five to seven years to have presence, a shade tree seven to 10 years or more. “Gardens really aren’t going to sing until they are three or four years old,” said landscape designer Barbara Katz, of London Landscapes in Bethesda. “People just don’t understand the time it takes to develop a real garden.”