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Pruning plants

Learn techniques and the purpose to pruning your plants.




Pruning:


Reasons for pruning:

  • To encourage new growth
  • To remove dead, broken, or diseased branches
  • To shape a tree or shrub
  • To maintain the shape and size of a tree or shrub
  • To remove suckers and spindly growth
  • To produce larger fruits or flowers


THE THREE MAIN TECHNIQUES TO PRUNING

Light Heading Back:
Light heading back is the procedure where branch tips are removed. This will control the shape of a mature shrub and increase bloom. The cut should be made approximately 1/4" above a healthy bud.

Severe Heading Back:
Severe heading back is the removal of approximately half of nearly every branch. This stimulates production of fewer, but larger flowers on a few strong stems.

Thinning:
Thinning is the removal of a branch to the ground or back to the main branch. This process will make the shrub less dense and encourage strong growth of the existing branches.

For all pruning techniques, the cut should be made at an angle a quarter of an inch above a bud. If cut any closer, the bud probably will not survive; any farther, the branch will die. The cut should be made toward a bud on the outside of a branch. This will generate foliage growth to the outside of the branch, giving shape to the plant. By angling the cut, water will easily run off, therefore, discouraging disease.


PRUNING TIMETABLE

Trees:
The best time to prune a tree is in the spring or fall, when there is no foliage. At these times, it is easier to get a view of the display of branches.

The first pruning should be done at planting time, which will stimulate growth. Begin by removing all but the thickest, healthiest branches. Each year, as the tree grows, remove one or two of the lowest branches in order to achieve the desired height of the main branches. While the tree is still young, be careful not to remove too many branches in a season, as the tree needs leaves to produce food.

Once the tree reaches the desired shape, prune only to remove broken or diseased branches and to remove crowded branches. Prune branches that interfere with buildings and power lines.

If two branches rub together, remove the smaller one. There should only be one main trunk per tree. If there is a secondary trunk, where the two meet (the crotch) will weaken and the tree may split. The split is an excellent place for insect infestation.

Shrubs:
The best time to prune shrubs is late winter or early spring, before flower growth, or, for spring flowering shrubs, after the flowering is complete.

To determine which branches can be removed without changing the natural shape of a shrub, remove dead wood, weak growth, and broken and diseased branches. Suckers should be removed from the origin of growth: the root. Dig away the soil and cut the sucker where it is attached to the root. Remove as many of the oldest branches as necessary - cutting at ground level. Every three years, remove approximately one third of the branches to rejuvenate a shrub.

Shrubs can be kept symmetrical by trimming the longer branches to suit the natural shape. Starting at the top and working down is the best way to shape a shrub.

Summer and fall-blooming shrubs flower on new wood - branches that have been produced the current season. Some examples are: Butterfly bush, Rose of sharon, Crepe myrtle, Summersweet and Abelia. These shrubs should be pruned in the spring before new growth begins.

Some winter hardy shrubs die back to the ground each year. In the spring, cut off all dead branches to about six inches from the ground, leaving at least two buds on each stub. New branches will grow from the roots as well as from the buds. For those winter hardy shrubs that do not die back to the ground, remove some of the oldest branches to encourage new growth.

Evergreens:
Cutting lower branches of coniferous evergreens should be avoided unless there is disease or the branches are dead. The removal of too many lower branches will make the evergreen appear to be top heavy. Once lower branches are removed, they will not fill in as the evergreen develops new growth from the tips of the branches.

Firs, Hemlocks, Pines and Spruces should be pruned after new growth. Arborvitae, Junipers and Yews should be pruned before new growth.

Firs, Hemlocks, Spruces and Yews need only be pruned to retain their natural shape.

Pines do not require pruning to maintain their appearance. To create a fuller Pine, cut the candles (new growth), before they harden, to half their length.

Juniper and Arborvitae should be pruned so the top branches do not overhang the lower branches. In doing this, the lower branches will receive as much sunlight as the upper branches.

Lilacs:
Lilacs produce flowers at the tip of the stems that grew the year before. Little pruning is necessary for Lilacs; to rejuvenate an old Lilac bush, cut a few of the oldest stems close to the ground. Most of the suckers should be removed, however, to have a dense lilac bush, some of the suckers should remain. To conserve the plant's energy, cut off the seeds when bloom is over.

Azaleas and Rhododendrons:
Rhododendrons may require some light pruning from time-to-time. To increase flower production next year, remove the current year's flower stem as soon as flowering is complete. Break out the flower head, being careful not to damage the developing buds.

Both Azaleas and Rhododendrons should be pruned after flowering. If severe pruning is necessary, do not cut any more than one third of the shrub in a season.

Roses:
Hybrid teas, grandifloras, and floribundas should be pruned in the spring when the buds are swelling, but before new growth has begun. Prune to about one- third to half the height and width each year. To remove dead wood, cut the canes to live green tissue. Entire canes that have died may need to be removed.

Shrub roses that bloom once, in the spring, should be pruned after flowering is complete. Remove all the dead wood and some old canes.

Climbing roses should be pruned twice a year - in early spring and again after they have bloomed. Climbing roses typically bloom on last year's canes, therefore, severe pruning is not necessary. To prevent cutting off flower buds, prune only the broken, dead and overcrowded canes. When flowering is complete, remove a few of the oldest canes, giving room for the new, current year's canes which will produce flowers next season.

Rambling roses, which are vigorous climbers, should be pruned after flowering. Prune the old canes to ground level. The new canes that have become too large to manage should only be lightly headed back.

Vines:
Pruning to keep a vine manageable is usually all that is necessary, and should be done while the vine is still dormant. As a general rule, vines that flower in the late summer or fall produce flowers and foliage on new wood, therefore, the wood from last season can be cut back or removed. Vines that flower in the spring or early summer produce flowers and foliage on old wood and should be cut back only to the point of green wood.