Shearing is an easy and quick method of pruning, but it can cause a shrub to look ugly and woody with bare branches in the center. An easy solution is to add in some thinning cuts to open up the bush to light and circulation. Shearing should be avoided in the case of flowering shrubs.
Renovation pruning can bring an old, overgrown shrub back to life. With this type of pruning, follow the rule of 1/3. In renovation pruning you can prune back ⅓ of the height with heading cuts and ⅓ of the oldest, thickest branches as far back to the ground as possible with thinning cuts. Repeat this 3 years in a row until the thick, old limbs are eliminated. This method can be performed on just about any bush. Spring flowering bushes can be pruned once the bloom period has ended. All other shrubs should be renewal pruned in late winter or early spring.
Severe renovation pruning is a simple, but harsh pruning method. Many plants, like Knock Out Roses, Ligustrum, and Smooth Hydrangea respond well to this type of pruning. Most fast growing plants tolerate this pruning well. Rejuvenation pruning can invigorate an aging, overgrown shrub that is struggling. There is no thinking or planning with this severe type of pruning. Just cut your plant back to 12 inches or less from the ground. Rejuvenation pruning should only be done in late winter or early spring.