What are some proper pruning techniques?
Let the plant you are pruning be your guide. Suckering shrubs like American cranberrybush viburnum, spireas, forsythia, lilac and red twig dogwood continually produce new stems. Gradual renewal pruning removes a few older, thicker, stems to ground level. Repeat yearly for three or four years on overgrown plants. By the end of this period you will have a smaller plant with leaves from top to bottom.
Rejuvenation (sometimes referred to as renewal) involves cutting the whole plant to the ground. Anyone growing privet, potentilla or Japanese spirea may have used this technique. All the stems are cut back to 4 to 10 inches above the ground. This type of pruning is stressful on the plant and often the gardener doing the pruning. This method is sure to generate fear from first time or timid pruners. Make sure the shrub you are pruning can tolerate rejuvenation pruning before you proceed. Even if the shrubs tolerate severe pruning it may not be the best solution. You may end up with a taller plant than you started with since all the energy reserves are directed into forming new growth. And some shrubs like potentilla and Japanese spirea get a bit floppy when pruned this way.
Try a variation on these methods to avoid floppy re-growth on potentilla and summer blooming spirea. Cut all the stems back halfway. Then remove half of the stems (older one) back to ground level. The taller stems support the new growth resulting in a smaller plant less prone to flopping.
Maintain the health and natural form of the plant by making all cuts at a slight angle 1/4 of an inch above a healthy bud, where a branch meets another branch or back to ground level. Cutting too close or too far from the bud results in stubs. These dead tips are great entryways for insects and disease. That is why I am not a big fan of shearing. Make sure to cut above a bud or stem facing away from the center of the plant. They determine the direction of the new growth.
You can reduce future pruning by training the plants to grow away not into the center of the plant. If you do shear shrubs make sure the top of the shrub is narrower than the bottom. This allows sunlight to reach all parts of the plants encouraging leaf growth from the tip of the branches to the ground.