Q: Our HOA of 40-plus years has numerous sheared shrubs and weβre trying to renovate and naturalize as many as we can. I hope you can follow up your tree pruning advice with some on the positive approach of hard pruning or rejuvenating some currently sheared, older and overly large Texas rangers and oleanders.
A:Β Renovating or rejuvenating older, overly large, or previously sheared shrubs extends the life and improves the aesthetic value of these plants. One method is to cut all stems to about 12-18 inches above the ground.
This is a severe measure and changes the appearance drastically, however, when done in early spring before bud burst, causes a great number of stems to grow just below each cut by mid-summer. At that time, about half of the stems should be removed and the remaining ones should be cut back to different heights.
Varying the height and cutting just above an outward pointing bud will stimulate growth of new branches out of the canopy. According to University of Arizona Horticulture Specialist, Ursula Schuch, this procedure works well for larger fast growing shrubs like Texas ranger and oleander and for slower growing shrubs like hop bush and creosote.
Some shrubs such as cassias, arborvitae, rosemary, and junipers do not respond favorably to this treatment and might die. A less severe approach to rejuvenating shrubs is to remove half or more of the older unproductive branches at the base of the plant or those growing into the canopy. This thins out the plant to a much greater extent than regular maintenance pruning.
Follow-up care requires removing a portion of the new shoots a couple of weeks later, which might be too numerous and result in an overly dense canopy.
A third method of rejuvenation that spans three to four years and is less noticeable requires removing about one third to a quarter of the oldest unproductive branches each year. This method requires thinning excess branches and cutting back the remaining new branches as described before.
A common practice that is not recommended except in the case of formal hedges and topiaries is shearing. Shearing shrubs means cutting back branches to a uniform surface using heading cuts. We see all sorts of examples in our area where shrubs have been sheared to resemble beer can and meatball shapes. It doesnβt just look weird; itβs bad for other reasons.
The maintenance costs for sheared shrubs increases because they require repeat shearing more frequently than they would need regular pruning and they use more water to recover from this harsh treatment. Shearing stresses plants and can result in decline or death.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to
