Spring is here. And homeowners are itching to get out in the yard and do something productive.
Ward Upham, a horticulturist at Kansas State Research and Extension, says one chore that homeowners can tackle right now is the pruning of certain shrubs.
“Often, gardeners approach pruning with trepidation, but it is not as difficult as it may seem,” Upham says. “Remember, not all shrubs need to be pruned, witch hazel for example, and certain shrubs should not be pruned this time of year.”
The purposes of pruning are to maintain or reduce shrub size, rejuvenate growth or remove diseased, dead or damaged branches. Deciduous shrubs are those that lose their leaves each winter. Evergreen shrubs maintain foliage all year and include yews and junipers.
The three groups of deciduous shrubs:
– Those that flower in the spring on wood produced last year.
– Those that flower later in the year on the current season’s growth.
– Those that may produce flowers, but those flowers are of little ornamental value.
Upham says shrubs that flower in the spring, such as forsythia, lilac and mock orange, should not be pruned until immediately after they have flowered. Though pruning earlier will not harm the plant, the quantity and quality of the shrub’s blooms will be reduced.
Shrubs that bloom on the current season’s growth are best pruned in late winter to early spring, Upham says. These include rose of Sharon, pyracantha, Bumald spirea and Japanese spirea. This also is true for plants that bloom from growth that has occurred this season.
“Pruning during the spring allows wounds to heal quickly without threat from insects or disease.” Upham says. “There is no need to treat pruning cuts with paints or sealers. In fact, some of these products may retard healing.”
Upham explains three basic methods used in pruning shrubs: thinning, heading back and rejuvenating.
Thinning
This technique is used to trim branches from a shrub that is too dense. This is done by removing most of the inward-growing twigs by cutting them all the way back to a larger branch or by cutting them back to just above an outward-facing bud. On shrubs with more than one stem, the oldest canes may be completely removed.
Heading back
With this method, the end of a branch is cut back to a bud. Heading back is used to reduce a shrub’s height or to keep it compact. Branches should not be trimmed to a uniform height, as this results in a “witch’s broom” effect.
Rejuvenation
This is the most severe type of pruning and may be used on multistem shrubs that have become too large and now have too many old branches to justify saving younger growth. All stems are cut back to 3- to 5-inch stubs. This is not recommended for all shrubs but works well for spirea, forsythia, pyracantha, ninebark, Russian almond, little leaf mock orange, shrub roses and flowering quince.
An additional type of pruning is “gradual renewal,” in which a few of the oldest and tallest branches are removed each year at, or slightly above, ground level. To maintain the shrub’s symmetrical shape, it may be necessary to shorten long branches.
Sources: www.oznet.ksu.edu, www.ag.arizona.edu
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Pruning tips
Pruning improves the health and safety of plants.
While pruning has a dwarfing tendency, it stimulates growth points into action.
In late winter, before bloom, take out the oldest and weakest canes at or near the ground to reduce height, thin and improve flower quality.
Some shrubs may need some shoots cut back if outside influences, such as shade, cause the plant to become out of balance.
For most summer-flowering shoots, cut back all shoots in early spring to near the soil line.
Source: www.ext.colostate.edu
