Shrubs are prized for their landscape value, whether they offer fragrant flowers, colorful stems or exfoliating bark. Yet they are also valued for being low-maintenance plants. After they've been established in the landscape, they typically require minimal care with the occasional watering, fertilizing and pruning. Every so often, shrubs need a little TLC to rejuvenate them.
You'll save yourself a great deal of labor in the first place by selecting slow-growing plants that don't need a lot of pruning. Eventually though, you'll have to take your clippers in hand and prune to control the size of shrubs, improve their shape and remove dead, diseased or injured wood.
Gather your pruning tools, such as hand pruners, loppers and a saw, and inspect them to make they're sharp and clean. Pruning with dull and dirty tools can make the process more difficult and ultimately injure plants by making ragged, incomplete cuts. This may prevent the wound from healing correctly and eventually result in weakened plants that are susceptible to diseases and pests.
When to Prune
Before pruning, think about the shrub's purpose in the landscape. If it's a flowering shrub, pruning at the wrong time of year can ruin the display. Some plants bloom on new wood, others on wood formed the previous year. A basic rule for flowering shrubs is to prune just after they've finished flowering.
Pussy willow and red-twig dogwood should be cut nearly to the ground in late winter to early spring in order to keep plants bushy and full. Leave only four to six inches of stem above the soil surface when you prune these plants.
Butterfly bush blooms on new wood. Prune severely in early spring, cutting it down to the ground (about four to six inches from the ground).
Rhododendrons and azaleas should never be pruned after September, when they're forming buds for next spring's flower display. Prune them just after they flower in late spring and early summer.
Making the First Cut
When pruning any shrub, first remove dead, diseased or injured wood, then any growth that crosses through the center of the plant to improve air circulation. Finally, step back and examine the natural shape of the plant. Unless you're doing topiary or a formal hedge, use the plant's natural growth habit as a guideline for pruning. Follow these steps for pruning your shrubs:
- To reduce a shrub's size, increase its bloom time and control its shape, remove some of the branch tips. This process is called heading back. Cut just above a strong bud, or node. This forces the plant's energy to focus on growth at that bud.
- To rejuvenate an overgrown, bushy shrub, cut away one-third of the branches to the soil line each year. Excluding shrubs that produces suckers yearly such as butterfly bush and some spirea, remove no more one-third to one-half of the shrub's canopy. Depending on the size of the plant, this process may take two to three years to complete so you don't shock the plant to death.
- To make a plant less dense, thin by trimming a few limbs to the ground or to a main branch. Thinning improves air circulation and discourages fungal diseases.
- To keep a plant symmetrical, cut off new shoots as they appear.
- To increase flower size, trim all branches back by one-third to one-half.
- To remove undesirable suckers, dig soil from around the base of the plant, and cut them off at the root.
- To keep growth dense, clip new shoots by half.
- To keep plants small, head back or thin them to the desired height.
- Give narrow-leafed evergreens a light shearing to keep them looking tidy and under control.