   Pruning Shrubs - May 15, 2002 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Pruning is an art and a science. The science is easy; one simply needs to take the time to study it. The art comes with experimentation, observation, and experience. Just because you bought a new pair of hand pruners or loppers (or worse: hedge shears), doesn't mean you have to run out and use them on every plant in your path. Some plants do really well without pruning. Others need an occasional pruning "tune-up" to remove crossing branches and dead wood. Most plants should never be sheared…ever! In this column, I will overview a few pruning strategies for woody shrubs. Most pruning problems begin when the wrong plant is planted in the right place. In other words: the plant simply outgrows the space it's planted in. You often see this with Photinia and Texas Ranger. These plants grow fairly fast and can get big. Being human, we try to control the growth by shearing them down to the perfect 3-foot shrub. The first shearing causes branching to double or triple as the lateral buds break in response. The next shearing simply compounds the problem by causing more lateral buds to break. Pretty soon, you have a bunch of little broom-shaped branch tips and unhealthy plants with bare patches in the canopy. Sound familiar? To revitalize a sheared shrub, look inside the plant and remove the broom-shaped growth and dead branches. Follow the bad branch to the point where it is attached to a larger branch and remove it. Do this with hand pruners, loppers, or even a saw if necessary. Be careful not to flush cut. Always leave the branch collar (swollen area near where the branch attaches) intact, as this tissue will callous over the wound. Try to remove the old, weak stems. Continue until you have corrected the problem but never remove more than 1/4 to 1/3 of the total live canopy during one growing season. Finally, if the plant is too large for the space, remove it and plant something that grows slower and stays smaller. Another common mistake is winter pruning spring blooming plants like lilac, Spirea, Pyracantha, Forsythia, redbud, and Wisteria. Winter pruning simply removes the flower buds causing the spring bloom to be lost. These should be pruned lightly, if at all, and then only after flowering has ceased. Summer flowering shrubs, such as chaste tree, crepe myrtle, Nandina, Abelia, and Rose of Sharon should be pruned in spring before growth begins. Like trees, shrubs should never be topped. This causes weak branching, lots of water sprouts, and leaves behind dead stubs. Older shrubs can be rejuvenated by removing older wood and leaving younger, healthier wood. This technique is especially well-suited to deciduous shrubs such as Forsythia and Spirea. It also works well with Nandina. This is the approach often used when pruning older rose bushes. Again, a good rule-of-thumb is never remove more than 1/4 to 1/3 of the total canopy in any given year. Here are some parting thoughts on shrub pruning:
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