Deb Babcock's gardening column appears Mondays in Steamboat Today.
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Ordinarily, a shrub shouldn't need pruning if you've selected the right size plant for a particular site. Sometimes it's necessary to prune for the health of the plant, to control its size, to promote new growth with better flowers or to correct damage caused by weather, disease, animals, etc.
The flowering time of your shrub will dictate the best time to carry out pruning. Generally, shrubs that bloom in the spring, such as lilac, chokecherry, forsythia or serviceberry should be pruned immediately after they finish blooming. That's because next year's blooms will take place on this year's new growth. By pruning away this year's seed pods, you encourage growth of new branches and more robust flowers for next year.
Shrubs that bloom in the summer should be pruned in the fall when they become dormant or very early in the spring before growth starts. That's because blooms will occur on current year growth and pruning will encourage new growth and more flowers. There are some late summer flowering shrubs that fare best in our climate by allowing branches to catch snow and build up a mound of protection for the winter. This includes most rosebushes, spirea and butterfly bush.
Generally, shrubs should not be pruned in late summer because this might cause new growth which could die if not hardened off before cold weather sets in.
If your shrubs are grown mainly for their foliage, pruning should take place in the spring before growth begins. Barberry, sandcherry, dogwood, buffaloberry and burning bush are examples of shrubs that are best pruned in the spring.
When pruning your shrub, bear in mind its natural shape and cut branches to maintain that form. To control shape, look where the buds occur. A bud that faces in toward the center of the shrub will create growth toward the middle while a bud that faces outward will tend do the opposite.
When you prune, first remove the dead, broken, diseased or criss-crossing branches. Use clean, sharpened tools to avoid contaminating the open wound.
Then remove stems and branches that detract from the natural shape of your shrub. Make your cuts on healthy wood at a slant about a quarter inch above the bud. If you cut back to a main branch, try to cut as close to the branch as possible and avoid short stubs. Never lop off the top of a shrub and avoid pruning too drastically.
Your shrub needs some foliage to produce food.
Sometimes, a shrub is just too far gone to be fixed by pruning away a branch here and there.
To rejuvenate a single stem shrub, prune severely to its basic limb framework. On a multiple stemmed shrub, simply prune back all stems to about 4 inches from the ground.
The best time to do drastic pruning such as this is in early spring.
If all this fails to create an attractive shrub, it's probably time to replace it.
Deb Babcock is a master gardener through the Colorado State University Cooperative Extension office in Routt County. Questions? Call 879-0825 or e-mail firstname.lastname@example.org.