Pruning Trees & Shrubs

Pruning can serve many purposes. It can keep a plant’s size in check, encourage flowering or fruiting, remove or deter pest and disease problems or help to improve the overall appearance of a plant by changing its shape.

Pruning Shrubs

Choosing the Right Tools

Good quality, well-maintained pruning tools are essential. You may need a pruning saw, long-handled loppers, hedge shears, pruners and gardening gloves. Be sure to keep all types of pruners sharp. Dull blades may crush a stem, leaving it vulnerable to infection from disease

Pruning to Shape


First observe the natural shape of a plant and then prune the plant in a manner that will allow the natural form to continue to develop. Remove any excess growth that obscures the basic pattern of its natural form. When pruning to shape, make your cuts above a bud or side branch that points in the direction you’d like the new growth to take. Try to eliminate branches that cross and touch one another. Crossing branches may rub together, suffering injury, and are usually unattractive, especially in deciduous plants out of leaf. Also, be sure to prune out dead, diseased and damaged branches whenever they occur.

Pruning for Flower Production

Flowering shrubs bloom either from new growth or from old wood, depending on the plant species. Before you prune, it is essential to determine its type of growth. This way, you can avoid inadvertently cutting out stems that would give you a flower display. Most spring flowering shrubs bloom from wood formed during the previous year. Be sure to wait until these plants have finished flowering before you prune them. Growth that the shrubs produce after flowering will provide blooms for the next year. Most summer flowering shrubs bloom on growth from the spring of the same year. These are the shrubs you can prune during the winter
dormant season without sacrificing the next crop of blooms.

When to Prune

As a general rule, if a shrub flowers after mid-summer, it should be pruned in early spring. If it flowers earlier in the year, pruning should be done immediately after flowering.

 

Shrubs that can be pruned in early summer:
(after flowering)

Azalea
Cotoneaster
Cytisus, Scotch Broom
Deutzia
Forsythia
Kalmia, Mountain Laurel
Magnolia
Philadelphus, Mock Orange
Rhododendron
Syringa, Lilac
Viburnum
Weigela

Shrubs that can be pruned in early spring:

Buddelia, Butterfly Bush
Caryopteris, Blue Mist Shrub
Clethra, Sweet Pepper Bush
Forsythia
Hibiscus syriacus, Rose of Sharon
itea, Virginia Sweetspire
Spiraea, Japanese Spirea
Tamarix, Tamarisk

Note: Prune evergreen shrubs (not including conifers) between June 1st and August 15th after new growth develops and hardens off. Prune conifers such as Pine, Spruce or Fir between July 4 and Aug. 15 after new growth has hardened off. Do not cut back into old wood, only trim the current year’s growth.

Pruning Trees

The objective of pruning is to produce strong, healthy, attractive plants. By understanding how, when and why to prune, and by following a few simple steps, you can achieve the desired look.  The are a few main reasons for pruning trees.

  • Remove limbs that cross or are likely to break because of a weak angle
  • Removing limbs that could fall and cause injury to yourself or a structure
  • Removing branches that grow into utility lines
  • Trimming brances that interfere with lines of sight
  • For aesthetic purposes

When to Prune

Conifers may be pruned any time of year, but pruning during the dormant season may minimize sap and resin flow from cut branches. Hardwood trees and shrubs without showy flowers: prune in the dormant season to easily visualize the structure of the tree, to maximize wound closure in the growing season after pruning, to reduce the chance of transmitting disease, and to discourage excessive sap flow from wounds.  Usually, the best time is during late winter when the temperature is above freezing.  Flowering trees and shrubs: these should also be pruned during the dormant season for the same reasons stated above; however, to preserve the current year’s flower crop, prune according to the following schedule:

  • Trees that flower in early spring—prune immediately after flowering (flower buds arise the year before they flush, and will form on the new growth).
  • Trees susceptible to fireblight – these trees, including many varieties of crabapple, hawthorn, pear and

    mountain ash should be pruned during the dormant season.

  • Flower in the summer or fall – prune during the dormant season (flower buds will form on new twigs during the next growing season, and the flowers will flush normally).
  • Dead branches – can be removed any time of the year.
  • An alternate method of conifer pruning is to cut back no more than half of the current years growth after it is hardened off in July though August in Ohio.

Pruning Cuts

Use the following decision guide for size of branches to be removed:  under 2” diameter – go ahead, between 2-4” – think twice, greater than 4”- have a good reason.

 

Crown Thinning

Assess how a tree will be pruned from the top down.  Favor branches with strong, U-shaped angles of attachment. Remove branches with weak, V-shaped angles of attachment and/or included bark.  Remove any branches that rub or cross another branch. Make sure that lateral branches are no more than one-half to three-quarters of the diameter of the stem to discourage the development of co-dominant stems. Do not remove more than one- quarter of the living crown of a tree at one time.

Crown Raising

Always maintain live branches on at least two-thirds of a tree’s total height. Removing too many lower branches will hinder the development of a strong stem.

Crown Reduction

Use crown reduction pruning only when absolutely necessary. Make the pruning cut at a lateral branch that is at least one-third the diameter of the stem to be removed. If it is necessary to remove more than half of the foliagefrom a branch, rem