The larger-leafed rhododendrons have many dormant buds that can be forced into new growth. Mock orange. Trimming rhododendrons is typically done for maintenance, shaping, and rejuvenation- as is the case for overgrown plants. Old rhododendron shrubs of various species come back as fresh and attractive as young plants after they are severely pruned for rejuvenation. What do you recommend? Rejuvenation pruning, also called renewal pruning, involves cutting some types of shrubs almost down to the ground, leaving only 6 to 24 inches. One is the removal of spent flowers (trusses) and any diseased or dead wood. Those are latent buds. A: Rhododendrons are impressive plants in a landscape. As long as an old, leggy rhododendron is not weakened by a disease, it tolerates and responds very well to a severe pruning, more commonly called a rejuvenation pruning by horticulturists. However, on very old wood, the dormant buds may have atrophied and are not viable. Rejuvenation pruning works on rhododendrons because they produce small buds all over the surface of branches, even the old ones. A: It's great that you're taking the trouble to dispose of potentially invasive plants correctly. Here is one example from my work site. Once established, most evergreen shrubs are fairly low maintenance and need little or no regular pruning. The Anah Kruschke rhododendron also has a better tolerance to heat and scorching sun than other varieties. The Anah Kruschke rhododendron (R. Anah Kruschke) is a cultivated variety that grows up to 5 feet tall and can tolerate winter temperatures down to minus-15 degrees Fahrenheit. OSU Extension faculty and Master Gardeners reply to queries within two business days, usually less. Prune your large rhododendron right after it finishes blooming. Community Rules apply to all content you upload or otherwise submit to this site. If you take the pruning one step at a time and break up the project across a few days, it won’t seem so impossible. You can consult any good source of information on perennials to find out how this is done and when. By pruning just above viable dormant buds, new healthy growth can be directed to obtain a more desirable shape. Rejuvenation pruning removes most of the branches of the plant, initi- – Anne Schmidt, OSU Extension Master Gardener, Dahlia breed: Scott's Caldera Katie Currid/The Oregonian LC-LC-, Q: I have several dahlias in my yard that grow well but have little to no bloom. Crystal Springs Rhododendron Garden, March 30, 2018. Photo: properlandscaping.com. Rejuvenation Pruning for Azaleas & Rhododendrons Because these are generally slow-growing shrubs, there is often a tendency to plant them too close to other shrubs or obstructions. Rejuvenation pruning consists of cutting down a plant to about 6-18 inches. One is the removal of spent flowers (trusses) and any diseased or dead wood. Flowering quince. However, there are some mistakes that you can make if you follow a generic pruning plan. Rejuvenation pruning, can be useful to reshape a plant. Weigela. Fortunately, they are actually not too difficult to prune back. (604) 729-2234 Some that do not sprout readily from old wood cannot be much improved. Pruning rhododendrons is not that different from pruning other types of flowers. To ask a question, simply go to the OSU Extension website and type in a question and the county where you live. Registration on or use of this site constitutes acceptance of our User Agreement, Privacy Policy and Cookie Statement, and Your California Privacy Rights (each updated 1/1/20). Fortunately, they are actually not too difficult to prune back. Bravely make big cuts if rejuvenation is required. – Marjorie Neal, OSU Extension Master Gardener. This major pruning may be a shocking experience for many gardeners. There are three common reasons for pruning rhododendrons: maintenance, shaping, and rejuvenation. Mark Graves/The Oregonian/OregonliveLC- Mark Graves. This major pruning may be a shocking experience for many gardeners. Are you feeding the plants properly? The larger-leafed rhododendrons have many dormant buds that can be forced into new growth. The pruning method for each is different. Fortunately, they are actually not too difficult to prune back. Forsythia. Cutting back a rhododendron leaves little more than stubs… but don’t worry, it will grow back. It would be very unfortunate to get any of these plants into our streams and wetlands. Maintenance pruning is the removal of spent flowers and old, dead wood. Spiraea. What this translates to is after the frost in fall when the plants die back. Because these are generally slow growing shrubs, there is often a tendency to plant them too close to other shrubs or obstructions. Somewhere down the road we will be rewarded with a less unruly plant. Rejuvenation Pruning. Bluebeard (Caryopteris) -- done annually. – Anne Schmidt, OSU Extension Master Gardener, Q: I have a small water garden and I need to safely dispose of excess salvinia, frogbit and water hyacinth. I have a rhododendron in my front yard that is completely overgrown to the point that it is taller than the lowest point of my roof. This growth may need subsequent thinning out to select the strongest, best placed shoots. Here are some questions asked by other gardeners. This makes neat little mounds of twigs that will explode with new growth come spring. In rejuvenation pruning, you cut all of the stems down to the ground in one go. This involves bravely making large cuts and significantly reducing the plant size. You will be removing all old wood, and the plant will begin producing new juvenile stems and new foliage shortly after pruning. In fact, excessive growth may require a heavy pruning. As you have noted all are potentially invasive. Rejuvenation pruning consists of cutting down a plant to about 6-18 inches. Flowering quince. All of them have the potential to be highly invasive. This works because rhodos are special. If in doubt, proceed cautiously, or seek expert advice. Weigela. Regular pruning maintains the shrub size and prevents breakage during the winter months by managing the structure. When to prune. Water Hyacinth (Eichhoria crassipes) also has “Quarantine” status in Oregon, but there are populations already here so it is capable of surviving here. By pruning just above viable dormant buds, new healthy growth can be directed to obtain a more desirable shape. Staggered renovation. Rejuvenation pruning calls for dras-tic cuts on old wood Rejuvenation pruning is best used to restore shrubs that have become leggy, overgrown, or otherwise unattractive. Phone: Rejuvenation pruning calls for dras-tic cuts on old wood Rejuvenation pruning is best used to restore shrubs that have become leggy, overgrown, or otherwise unattractive. I have considered setting them out to dry prior to composting but wonder if the seeds would still be viable. Sunset Western Garden Book has an excellent chapter on dahlias, and OSU Extension has a good publication about growing dahlias. Rejuvenation Pruning. Note to readers: if you purchase something through one of our affiliate links we may earn a commission. This method will have to be adjusted according to how the basal framework of individual shrubs it set at ground level. Witch hazel. The best and safest way to dispose of any invasive plant material is to bag it and put it into the garbage – not compost it. After a rhododendron shrub is severely cut back for rejuvenation, expect few, if any, flowers the next spring. Go slowly, one carefully considered cut at a time. As these plants are potentially invasive, I want to know of a safe way to compost them. I made this vid for my daughter to show her what I've done in her dad's yard at her childhood home. Photo: properlandscaping.com. The seeds would probably survive composting. Then watch. Most rhodos produce seeds and you can get your rhodo to concentrate on growth by removing the spent flowers. Follow up this hard pruning with a feed and mulch in spring. – Multnomah County. Plants that respond well to rejuvenation include, forsythia, lilac, and spirea. With a rhododendron or azalea that lives up to their reputations as the … That's it. I prefer hand pinching. This will mean that in years to come - just as the shrub is reaching its full glory, there will be a need to take drastic action by way of cutting down hard. When did you last dig and divide, for example? This rejuvenation pruning was done at a corner unit where there was a problem with vehicle sight lines. Large clumps of tubers on one plant should be divided. Administrative Mailing Address: Unlike many shrubs, Rhododendrons seldom require pruning, although they may benefit from an occasional maintenance trim. The instructions below are specific to rhododendrons, and will ensure that you prune them such that you increase their beauty and are still able to enjoy them season after season for some time to come. Rejuvenation pruning of Rhododendrons Rhododendron in need of hard pruning In more extreme cases, if your Rhododendron has become overgrown/leggy or you have taken over a new garden that has not been maintained for a while, you will need to utilise a more drastic pruning technique called rejuvenation and the good news is Rhododendrons usually respond well to hard pruning. As the shoots grow in the warming weather, add more soil gradually until you reach the ground level. It’s done by removing the extra branches on a large scale so it’s essential to be sure of this technique before starting. Pruning of hardened wood can be done at any time except during periods of freezing weather. Some that do not sprout readily from old wood cannot be much improved. In rejuvenation pruning, you cut all of the stems down to the ground in one go. A tip I have seen time and time again is: when you are doing some rejuvenation pruning, don’t forget to … I'd like to prune it way back, but I've heard that it won't bloom for years if we do. Rhododendrons often have three or more main branches rising from the crown of the plant. Spiraea. Other times risk being too early or too late. Just follow the branch down to the last whorl of leaves you want to keep and cut just above those leaves. This is what I recommend to clients who wish to keep their rhododendrons from getting too big. What’s yours? Photo: properlandscaping.com. Use hand snips if you are worried. Rejuvenation pruning removes most of the branches of the plant, initi- If not, when? If in doubt, proceed cautiously, or seek expert advice. The rejuvenation prune. One way of doing rejuvenation pruning is by cutting back the main branches of the plant. How do you treat a stem canker in a maple tree. Pinch off flower clusters (trusses) soon after flowering and prune for size. Most rhododendrons respond well to pruning. A tip I have seen time and time again is: when you are doing some rejuvenation pruning, don’t forget to … When pruned properly, the result is a fuller plant that produces an abundance of flowers. Prune your large rhododendron right after it finishes blooming. james@properlandscaping.com Most rhododendrons respond well to pruning. If your location does not regularly reach the low 20s freezing weather, you can leave them in the ground until spring. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Advance Local. If your plant has become quite leggy with old wood, then what you’ll need to do is rejuvenation pruning. – Multnomah County. This may delay flowering for several years but will result in a more manageable shrub. – Josephine County, A: You must wait until the current plantings have “rebuilt” the necessary strength in the tuberous roots to bloom again. Now what? In subsequent years you can continue that process and shape other parts of the plant to a more appropriate form for your landscape. This may delay flowering for several years but will result in a more manageable shrub. Examine their bark and look for tiny pink dots. Rejuvenation pruning, can be useful to reshape a plant. The Art of Pruning: Timing and Techniques Pruning is one of the best things you can do for your shrubs. Mock orange. Subscribe to OregonLive. Rhododendrons are forgiving plants. Witch hazel. My husband advocates pulling it out and planting an azalea there. That's it. If you have an overgrown shrub that is no longer flowering, try rejuvenation pruning in early spring by cutting all the stems back to the ground. This year prune out several selected taller branches by following them to a growth point – a main stem – then removing them. Take your time and prune over a couple of years. Plants that respond well to rejuvenation include, forsythia, lilac, and spirea. But what if your rhodo is too big? When spring arrives, after the last frost, dig holes at least a foot deep, place the tuber and fill the hole about a quarter full. By taking action you are doing your part to prevent their spread here in Oregon. The second pruning action is for shape. […]. You can cut back woody branches into areas where no leaves or lower twigs exist. Many rhododendron spe-cies and hybrids can be severely pruned and come back as good as new. Rejuvenation Pruning for Azaleas and Rhododendrons. We strongly suggest you consult some good references for a thorough understanding of this beautiful addition to your flower garden. Kym Pokorny | For The Oregonian/OregonLive. Rejuvenation pruning, sometimes called renewal pruning, is used to restore and reinvigorate older shrubs that have “thinned out” over time. So out came the saw as soon as the request was made. For rejuvenation pruning, you need to cut each of the primary branches forming the main frame of the plant, carefully. Perhaps there are other factors causing the low bloom. Red-stemmed dogwoods. Many rhododendron spe-cies and hybrids can be severely pruned and come back as good as new. Can I transplant them now? If you have an overgrown shrub that is no longer flowering, try rejuvenation pruning in early spring by cutting all the stems back to the ground. This is extreme pruning! Deutzia. Rejuvenation Pruning. Reduced to 30%. (Too much nitrogen, for example, causes green growth at the expense of blooms.) First, the ideal time to do undertake rejuvenation pruning is not after flowering (that’s when you do light pruning), but rather early in the spring, before the start of the growing season. Rejuvenation Pruning for Azaleas and Rhododendrons Because these are generally slow growing shrubs, there is often a tendency to plant them too close to other shrubs or obstructions. Others that sprout abundantly should not be opened excessively to light. Most rhodos produce seeds and you can get your rhodo to concentrate on growth by removing the spent flowers. Always aim to cut above these buds. It even creates more flowers as the shrub redirects its energy into flower production rather than overgrowth. Pruning, when required, is generally carried out in mid to late spring. Forsythia. Deutzia. Please support high-quality local journalism. There are three pruning actions associated with rhododendrons. Others that sprout abundantly should not be opened excessively to light. Pruning large rhododendrons can seem like an overwhelming undertaking, but it doesn’t need to be. Normal pruning takes precedence with younger shrubs. Do this soon after flowering before the new buds get big and set. This will mean that in years to come – just as the shrub is reaching its full glory, there will be a need to take drastic action by way of cutting down hard. However, on very old wood, the dormant buds may have atrophied and are not viable. Pruning is spread over two or three years to gauge response or maintain the natural shape. Rejuvenation pruning requires faith. Maintenance pruning: Maintenance pruning is performed on rhododendrons just after they have flowered. The best time to perform the rejuvenation pruning is winter while the plants are dormant. I plan on doing some rejuvenation pruning and cutting it back so it is only about 6 feet tall. These branches, called primary branches, form the basic scaffold of each shrub. Cutting back a rhododendron leaves little more than stubs… but don’t worry, it will grow back. Latent buds in action, a cluster of four buds below the cut. Email: Do this soon after flowering before the new buds get big and set. Incidentally, Sunset recommends a lightly shaded area rather than full sun for dahlias. Some shrubs will have a single main stem from which the framework branches grow. Now is the perfect time to prune, after this year's blooms and before the buds form for next year's flowers. We are talking only of Rejuvenation Pruning of older shrubs. Remember! The second type of rejuvenation pruning involves cutting off the trunk of the rhododendron shrub to 6 to 12 inches from the soil. Deciduous shrubs that respond well to rejuvenation pruning include: Lilac. Salvinia (Salvinia minima) is listed as “Quarantine” by the U.S. Department of Agriculture, Noxious and Invasive Plants in Oregon. I'd rather keep the rhododendron but in a much smaller version, and I'm willing to forgo blooms for a year or two to do so. Not much to look at right after pruning. Azaleas, which are also members of the Rhododendron genus, are much The main goal of rejuvenation pruning is height reduction, and in many cases, plants may be reduced in height by 75 to 90 percent. This article, How and When to Prune Rhododendrons, from The American Rhododendron Society has excellent additional information. © 2020 Advance Local Media LLC. Faith, that nature will do her job. Such plants fall into RHS Pruning groups 8, 9 and 10 . Some people use a box of wood shavings or sawdust to put around the tubers to better avoid any rotting. A rhododendron shrub needs extra care for the first year or two after severe pruning. There are three pruning actions associated with rhododendrons. If you take the pruning one step at a time and break up the project across a few days, it won’t seem so impossible. When to prune. Pruning a rhododendron is normally done for maintenance, shaping, and rejuvenation. This video, from the local garden program, Garden Time, shows you how to do this: Pruning Rhododendrons and Azaleas. I prefer hand pinching. Rejuvenation pruning. Red-stemmed dogwoods. I am aware that they won't survive in cold temperatures but was not certain if it got cold enough in Portland to kill them off in a compost site. In this case we employ pruning action three: rejuvenation, which sounds better than renovation. It is important to remove the flower stems from the shrub once blooming has stopped. […] I have also done renovation pruning on rhododendrons. Q: I love our deep red rhododendron, but it has grown so big that it blocks our front window completely. Pruning of hardened wood can be done at any time except during periods of freezing weather. Drivers couldn’t see properly when turning. Just be careful so you don’t injure the buds below. 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