Do you have a yard full of woody ornamentals? Are you unsure of when or how to prune them?
With diverse growth habits and varying pruning requirements, it can be overwhelming to try to figure out when and how to prune each variety. Not pruning correctly, or at the wrong time, can lead to plants to become irregular in shape, more vulnerable to cold damage or pests, or less likely to flower at their full potential. By understanding the importance of timing, using correct pruning cuts and working with proper tools, you can prune woody ornamentals with confidence.
When to prune
With flowering ornamentals setting buds at various time of the year, it can be confusing to know the best time to prune.
Try remembering the May rule: if the plant blooms before May, prune after flowering; if the plant blooms after May, prune just before spring growth occurs (February–early March).
A lot of our flowering ornamentals, such as forsythia and azaleas, set their flower buds in the fall. Pruning these woody plants in the winter would remove these buds and severely limit the flowers available come spring.
Summer flowering ornamentals, such as abelia and chaste tree, set flower buds on new spring growth and will not be affected by winter pruning.
As with everything, there are some exceptions to this rule. Oakleaf hydrangea, which sets its flower buds the season prior, as well as late-flowering azaleas, which bloom in May, June or July, should be pruned after they flower.
Woody plants grown more for their foliage, not flowers, can be pruned anytime during the winter, spring or summer months.
When pruning, it is important to remember that wherever the plant is cut regrowth will be stimulated, generally happening within 6 to 8 inches of the cut.
The harsher the pruning, the more regrowth you will have. There are two basic types of pruning cuts: heading and thinning. Each cut generates a different response within the plant and should therefore be used for specific occasions in the landscape.
A heading cut is the most invigorating, as it encourages regrowth near the cut. As a result, the plant will become more compact in shape and will lose its natural form.
Conversely, thinning cuts remove an entire limb or branch back to another branch, bud or the trunk. This cut is the least invigorating, as new growth will occur on the untouched limbs and/or branches. This cut allows the plant to stay in a more natural shape and leads to a fuller looking plant.
How to prune
If branches are larger than 2 inches in diameter, make sure to use the three-cut sequence to avoid damaging the plant — the first cut should be about 1 foot out from the trunk and one-quarter to one-half of the way through the underside of the branch, the second cut should be a few inches away from the first cut one-quarter to one-half of the way through the upper side of the branch, and the third cut should remove the branch just outside the branch collar.
For most pruning tasks, you can use hand pruners, loppers/lopping shears, pruning saws, pole pruners or hedge shears.
Hand pruners come in two basic types, scissor action or anvil, and are used to cut small branches up to one-half inch in diameter. If the branch is larger than one-half inch but smaller than 2 inches in diameter, use loppers with longer handles and larger blades. A pruning saw, much like a woodworking saw, should be used on branches larger than 2 inches in diameter. When branches are out of reach from the ground, consider using a pole pruner. If you want a nice clipped looked, the best tool for the job will be hedge shears.
Pruning is an essential management task if you want strong, healthy plants and an attractive landscape. To be successful in your pruning endeavors, make sure that you understand appropriate pruning times (remember the May rule), use the correct pruning cuts for the task at hand (heading vs. thinning cuts), and work with the right tools for the job.
To learn more about proper pruning techniques, see University of Georgia Cooperative Extension Bulletin 961, "Pruning Ornamental Plants in the Landscape," or Bulletin 949, "Basic Principles of Pruning Woody Plants."