As shrubs and trees are noticed in the landscape, the need for pruning comes to mind.
Not all plants require pruning. However, pruning corrects undesirable growth such as low-hanging branches, controls size and shape, prevents crossing and scrubbing of branches, thin dense growth, removes dead and damaged wood, and flower making is encouraged.
When to prune, proper removal of branches is more important than a date on a calendar. The key is not to cut the branch collar or leave a bud.
Cutting too close removes tissue that signals the plant to set boundaries for resistance to disease spread. Leaving the stub prevents the formation of a border and results in decay spreading from the stub to the tree.
All pruning cuttings should be returned at or just above a growing point. For example, remove branches just above the bud, above the side branches, back to the main branch or trunk, or back to the ground.
Another key is to keep the pruning equipment sharp. A clean cut builds callus tissue on the wall on its own faster and causes less damage to the tree. After removing the branch, allow the tree to use its own defenses to protect itself.
Bypass type hand pruners and two-handed lopping shears with scissors cutting action cleanly cut the stem without crushing. Hand pruners cut the stems to three-quarters of an inch wide.
Attempting to cut larger branches risks producing poor cutting and/or damaging the scissors. Shearing branches up to 1 to 1.5 inches in diameter.
Pruning saws are cut with pull strokes. The narrow blades fit into tight spaces and make clean cuts. They are recommended for removing branches that are more than 1 inch wide.
Disinfect tools after each cut, especially when cutting a diseased tree such as crab apples affected by fire blight, by placing Lysol or 70% denatured ethyl alcohol on the blades. Disinfect the tools before cutting the next plant.
The worst time to prune is at bud break in the spring. The shrub or tree uses all the stored energy from last season to form leaves. At this time, the injuries are more severe.
Another undesirable time to prune is during leaf fall in the fall. The plant needs energy to close the surface area where the leaf is attached.
Furthermore, do not cut down a tree or shrub when the wood is frozen. It destroys the pipes that carry the plant’s water called the xylem. Branch damage appears during hot, dry weather when water cannot move the branch towards the leaves.
The flowering period of the ornamental shrub or tree is one way to determine when to prune. If showy fruits are characteristic of the plant, remember that fruits are formed from flowers. Removing the flowers also removes the fruit.
For example, shrubs that bloom before the end of May should be pruned during or immediately after flowering. The flowers are formed on the wood from last summer.
By pruning them immediately after flowering, the maximum time before winter is allowed to form wood for flowers next season. If cut during the winter or before flowering in spring, the flower trunks will be removed and the blooms will be reduced or eliminated for the coming season.
Some of the early flowering shrubs are barberry, flowering quince, cornelian cherry, deutzia, forsythia, holly, mountain laurel, privet or ligustrum, honeysuckle, magnolia, mock orange, firethorn, hawthorn, azalea and rhododendron, black jetbead, thunberg spirea , bridalwreath spirea, Japanese snowball, common lilac, Chinese lilac, French lilac, and viburnum.
Shrubs that bloom after the end of May should be pruned in winter or spring before new growth begins. They bloom on wood formed in the current spring or summer. Examples of summer-flowering shrubs are five-leaf aralia, glossy abelia, butterflybush, beautyberry, summersweet clethra, rose of Sharon, hills of snow hydrangea, peegee hydrangea, oakleaf hydrangea, crape myrtle, and hybrid tea rose.
Some shrubs can be pruned slightly before and after flowering. This often increases flowering and fruit production and can result in second flowering throughout the year. Examples of this group include glossy abelia, butterflybush, red twig dogwood, spreading cotoneaster, multiflora cotoneaster, Oregon hollygrape, Anthony waterer spirea, Frobel spirea, snowberry, and wiegela.
Ornamental trees that bloom before the end of May should be pruned immediately after flowering. These include redbud, magnolia, flowering dogwood, hawthorn, crabapple, flowering cherry, flowering pear, flowering plum, horse chestnut, buckeye, serviceberry, fringetree, silverbell, witchhazel, holly, and chestnut.
Ornamental trees that bloom after the end of May should be pruned in winter or spring before new growth or budbreak begins. These include golden rain trees, mimosa, Japanese pagodatree, sourwood, and other flowering trees.
Some trees, such as birch, yellowwood, elm, pine, spruce, fir, and maple, can bleed profusely if pruned in late winter to spring. Bleeding or loss of sap will not harm the tree but may be unsightly or messy. Bleeding can be reduced by pruning such trees when they are already full of leaves already in June.
Annette’s tipsDo not put paint or tar where a branch in a shrub or tree has been removed. Research shows that pruning paint retains moisture, increases decay, and prevents the formation of wound wood roll to close the area.