Older shrubs that have become a tangle of unproductive stems may require a more extensive program of thinning cuts, called renewal or renovation pruning, that takes at least three years. On shrubs with multiple stems that grow up from the base, like lilac, viburnum, forsythia, and dogwood, gradually remove all of the old stems while leaving the new, flower-producing growth untouched. Eventually, the new flower-producing stems will completely replace the lackluster old growth.
Neglected shrubs may call for a more drastic approach: hard pruning. Most deciduous shrubs that respond well to renewal pruning can also take hard pruning, as will a handful of broadleaf evergreens, such as privet. Using loppers and a pruning saw, cut back all stems to within an inch of the ground during the plant’s winter dormancy. Come spring, the plants will quickly produce new shoots from the base. Of course, this technique will leave you with little to look at while waiting for the new growth. Contact us 425-406-0424