Shrubs: Early spring can be a good time for some deciduous shrubs to be pruned, and a poor time for others. The determining factor for pruning is when the shrub blooms. If a shrub flowers before June 15, prune it immediately after it flowers. These shrubs would be considered spring-flowering shrubs.
Examples would be lilacs,forsythia,viburnums, honeysuckle, mock orange, and weigela. If a shrub flowers after June 15, prune in the winter or immediately before new growth starts. These shrubs are considered summer-flowering. Examples would be hydrangeas, roses, Japanese spirea, potentilla and smokebush.
Pruning for most mature shrubs consists of thinning, heading back, rejuvenation, shearing, pinching and/or deadheading:
? Thinning cuts are used to maintain a shrub's desired height and width. This technique is the most common and best way to renew a shrub. Thinning preserves the overall plant shape and is particularly useful for shrubs that sucker from its base. Remove interior branches with loppers or a pruning saw back to the base of the plant or the point of origin. Remove only 1/3 of the largest branches at one time.
? Heading back can be used to reduce the height of most types of shrubs. This technique entails removing each branch back to a larger branch or bud. When pruning back to a bud, cut the branch on a slight angle to within 1/4 inch above the bud. DO NOT leave a stub. Disinfect your pruning tools with alcohol or a 10 percent bleach solution after each cut to avoid spreading diseases. Wound treatments are not recommended and can actually slow down woundclosure.
? Use the rejuvenation technique for shrubs that are overgrown or leggy, and for shrubs that sucker readily from the base. Cut the entire shrub back to a height of four to 10 inches from the ground when the shrubs are dormant. Shrubs that can tolerate rejuvenation pruning arebutterfly bush, Annabellehydrangea, potentilla, and Japanese spirea.
? Shearing: This technique involves the removal of new shoots using hedge shears. Shearing should be used only on formal hedges. Examples of shrubs that can be sheared into formal hedges are yews, boxwood, hemlock, and arborvitae. Maintain the base of formal hedges wider than the top to insure adequate light penetration to the bottom of the hedge. Each time you shear a hedge, leave one inch of previous growth to allow for the plant to regrow. Most shrubs should NOT be pruned with hedge shears. For most shrubs, shearing will eliminate the shrub's natural form, will reduce the amount of foliage and flowers in the shrub's interior, and will cause a proliferation of shoots that will make the shrub unsightly.
? Pinching: This technique involves the removal of shoot tips allowing for additional side branching. Pinching increases the bushiness of a shrub. This type of pruning can be done on smaller shrubs in spring, or on certain evergreens.
? Deadheading: This technique involves the removal of spent flowers by hand. For some shrubs such as Japanese spirea, deadheading can encourage a second flush of flowers.
Evergreens: Evergreen trees such as pine, spruce, fir, and Douglas-fir, require little pruning. These trees typically have a broad, pyramidal form with low branches, and should be left intact. DO NOT remove lower branches as thisdestroys the natural aesthetic form of the tree. NEVER remove the main, central stem. DO remove crossing, dead, diseased, or broken branches. Also remove individual branches to help maintain the tree's natural outline. When pruning large branches, make sure to use the three-point method of pruning.
? Pines: New growth in pines occurs once a year from terminal buds. To maintain a more compact, densely branched habit, removeapproximately 1/2 to 2/3 of the elongated terminal buds (candles) before the needlesexpand in spring. Candles can be pinched or twisted in half. Do not cut branches back to older growth farther down the stem. Pines produce buds only at the tips of the current season's growth and will not produce new shoots farther back down the stem.
? Spruce, fir, and Douglas-fir: New growth in these trees occurs once a year fromterminal buds. To maintain the tree's natural shape andpromote denser growth, cut the tip of the branch back to a lateral bud. Do not leave branch stubs. In early summer, you can also remove 2/3 of an unbranched tip to keep the tree fuller.
? Arborvitae and yews: These evergreen trees and shrubs have latent (dormant) buds farther back down the stem. Therefore, you can shear these evergreens in late spring or early summer after new growth has expanded. You can also prune them in spring before the new growth has expanded because any subsequent growth will hide the pruning cuts. You can also prune individual branches back to a bud or a branch to encourage more compact habit. If these evergreens are used in formal hedges, maintain the base of the hedge wider than the top to insure adequate light penetration to the bottom of the hedge.
? Junipers: These shrubs require little pruning. They have scale and awl-like foliage that can be tip pruned in summer. Selectively prune branches of these plants back to a side branch, so that pruning cuts are hidden under foliage. These plants should NOT be sheared or cut back to older, non-leafy areas because this type of pruning would take years for new growth to conceal. Do not prune these plants after August, as the new growth will not harden off sufficiently before winter.
Where severe pruning is necessary, spruce will recover from cuts back as far as 2-year-old wood. Firs can be cut back as far as 3- or 4-year-old wood. However, if sited correctly, pines, spruce, and firs should require little or no pruning.
Trees: Late winter/early spring is generally a good time for pruning a variety of shade trees. Pruning can help control the size of a tree, direct growth, influence flowering or fruiting, or maintain plant health and appearance. Pruning can also increase the safety of a tree by removing broken, diseased, dead, ordying branches. Dormant pruning is nice since it allows you to see what needs to be pruned since the leaves are off. Also wounds tend to heal, or callus over, faster in this time period. It's best tocomplete pruning before buds break, however. Also, avoid "bleeders" such as maple, birch, and elm. Excessive "bleeding" could weaken the plants making them more susceptible to insects and diseases and also fresh "bleeding" could actually attract insects.
Assuming it's a good time to prune a shade tree, where does one start? Start byremoving damaged or broken branches. Try to promote a strong framework to the tree. Thin out growth that is too congested. When deciding what branches to remove,consider where the branch is growing and what potential problems it may run into as it gets larger. How much growth to remove is sometimes difficult to say, but keep in mind the tree needs foliage this season to produce food for itself and you can always cut off more next year.
Make sure you've got the proper equipment, including a pruning saw, loppers, and hand shears. Use each toolaccording to the cut that needs to be made. Do not apply wound dressing to the cuts. In general, wound treatments, such as tree paint or wound dressing, are not recommended. These compounds slow down wound closure and promote decay.
Make sure that you are using proper pruning cuts so the tree will be able to heal on its own. Also make sure not to cut into the branch bark ridge or branch collar. The branch collar area needs to remain after removing a branch, this will allow for callus materials to grow and close the cut.Remember not to leave stubs as they tend to invite decay.
For more information on pruning or if you have other horticultural questions, please call the Yankton County Extension Office at 665-3387.