Western red cedar (Thuja plicata) is a large, evergreen tree in the cypress family. In cultivation the tree will grow to 60 feet in height with a 20-foot spread. If trained when immature, several western red cedars, planted 2 feet apart, create an evergreen and fragrant hedge. When your hedge grows to the desired height, allow it to grow 6 inches beyond and then prune back the new growth. New growth sprouts from old wood, so the plant will quickly fill in even a heavy pruning. Prune the western cedar hedge in early spring or late summer.
Remove any dead branches by cutting them off back to the trunk.
Begin shaping the hedge at the bottom and work your way up. The final shape should be rounded at the top, with the sides gradually angling out so that the base is wider than the top, according to master gardeners with the University of Arizona. Stand back periodically and check your progress to make sure that the hedge isn't becoming uneven.
Clean the soil around the hedge of all pruning debris. Rake up old mulch and dispose of it.
Add a new, 3-inch layer of mulch to the soil beneath the hedge. Don't allow the mulch to touch the base of the western red cedar hedge and spread it out to the tips of the outer branches.
Water the western cedar hedge as you normally would.