The average landscape is said to be planted and last eight years but many plants will perform much longer with the proper planning and care. If you plan and give space for the mature size of the plants, the bulk of the landscape will last decades. However, customer expectations are often of a newly landscaped property that instantly looks established. This style leads to overcrowding and constant pruning. Also, with the drought of 2011-2012 and winter freeze of 2013-2014, many plants checked out faster than expected.
Some big woody plants can be rejuvenated over the years. Using the 1/3 rule, remove a third of the oldest wood each year to keep new wood coming on. This will keep the plant controlled in size. Another method of keeping a plant in check, is to do a hard cut. Take the plant to the ground and it will come back from the root. This can be done if the plant is in good health but has just gotten out of control. It will take 2-3 years for a plant to recover from the hard cut method.
With some plants, constant shearing will set them up to fail. The continuous pruning limits the leaf surface area on a plant and can lead to decline. The plant will not be able recover if it also experiences summer scorch or an insect infestation such as spider mites.
On many plants, rejuvenating is easy to do. I like to let the spring flowering plants flower first and then cut back hard. On later flowering plants, go ahead and start pruning early in the season. This will give you the most regrowth as possible for the next year's flower show. If you cannot rejuvenate an older shrub, plant replacement may be necessary to match existing shrubs.
Don Mann, Certified Arborist, Certified Chemical Applicator, Loma Vista Nursery