Thuja Green Giant
This is an extremely fast-growing evergreen that grows approximately 3 to 5 feet each year after its roots become established in a location. The tree is simple to grow and provides a thick wall of foliage when several trees are planted close together. These trees are tolerant of drought, resistant to diseases and insect pests and adapt easily to a variety of locations. Green Giants don't have to be pruned and stay fairly unvarying in their shape. Planted 5 to 6 feet apart, they quickly grow into a dense wall of trees. These are hybrid trees and can only be planted by rooting a branch. As with all evergreen trees, the Thuja stays green year round. Green Giants also have a bonus trait: They give off a delightful aroma that makes them extremely popular with homeowners.
Nellie Stevens Holly
These trees are planted 5 to 6 feet apart and grow into a thick, green wall. They grow quickly at a rate of around 3 feet each year and don't require a lot of care in order to thrive. In fact, they can pretty much be stuck in the ground and forgotten as they are extremely hardy. In the winter, they grow red berries that contrast nicely with the green leaves and are very attractive to wild birds and squirrels. These trees stay green year round and grow equally as well in the shade as they do in full sun. The natural shape of these holly trees is a thick pyramid that reaches from 15 to 25 feet tall, but they can be trimmed in other shapes as well and kept short if desired.
Leyland Cypress Trees
These trees are the most loved of all the privacy trees as they grow quickly at a rate of 3 to 5 feet a year, are drought tolerant and have needles that are soft to the touch. They remain green year round and adapt easily to different types of soils including sand and clay. To grow Leylands as privacy trees, they need to be planted 6 feet apart and don't require trimming to grow into a natural pyramid shape. Leylands grow best and strongest when the root ball is left intact during transplanting.