Home » Misc » When to trim rhododendron

When to trim rhododendron


Pruning Rhododendrons — Seattle's Favorite Garden Store Since 1924

Dan Gilchrist

Pruning

Dan Gilchrist

Pruning

Rhododendrons, among the Maritime Northwest’s most beloved plants, can vary from two-foot-high dwarf shrubs to 30-foot trees. They are often multi-trunked, or single-trunked but branching into three or more main trunks close to the ground. Most varieties don’t typically need a lot of pruning for their first several years. Some stay compact and tidy; others develop an open habit and need little pruning other than occasional thinning and nipping back of a few wayward shoots.

Over time, many rhodies grow a dense weave of thick-wooded branches, and the thought of pruning one can intimidate all but the most experienced gardener. Of course, we are here to help! Many of the principles of pruning trees and shrubs that we have covered in other blog posts (like Pruning 101) also work for rhododendrons. But rhodies can pose a few unique challenges.

Let’s start with some basics. Most pruning projects are a combination of thinning and heading cuts. Thinning tends to disperse and often slow down growth. It reduces the density of a plant. It’s best to start pruning with a “clean out” from the inside of the plant, removing branches which are dead, broken, diseased and crossing or chafing each other.

Heading (including pinching and shearing) tends to concentrate and stimulate growth. It increases the density, such as in hedging. The majority of cuts during pruning should be thinning cuts unless you are maintaining a hedge or renovating a tree or shrub by severely cutting back.

For most pruning, leave a minimal stub when you cut off a branch. Don’t leave a long, ugly, dead end branch to die off and attract pests. But also don’t cut it so close as to damage the collar tissue on the mother branch, which it needs to grow over the wound.

Rhododendrons are somewhat unusual in that they will often resprout from cut, bare (living) branches. We describe this advantage under RESTORING below.

To identify whether a bare branch is still alive or dead, make a little scratch in the bark, revealing the thin cambium layer just below. If it's bright green, it's still alive and might still sprout this season. If it's brown, rotting or dry looking, it's dead.

Note that on larger rhododendrons with thicker branches, small hand pruners might be too small for most cuts. For these you may need loppers and pruning saws.

A thinning cut redirects growth to a specific branch.

A heading (shearing) cut forces dense growth on the shrub’s face.

Basic thinning of a shrub: removing random inner branches reduces density while preserving the plant’s shape and character.

WHY PRUNE?

As with pruning any plant, ask yourself these questions:

Has it become an opaque blob in the center of your garden and you wish to make it a bit more open and treelike? Read about THINNING below.

Is it planted in too small of a space and you want to reduce its size or just head it back a little? …REDUCING may be the answer.

Is it a leggy, sparsely blooming shrub that you would like to develop more leaves and flowers like it used to? …let’s talk about RESTORING.

Note: Just because you’ve always heard that you’re supposed to prune your rhododendron doesn’t mean you’re obligated to do so. Plant maintenance should not be a prescribed, automatic chore, but rather a flexible solution to a specific problem.

TIMING

You can prune a rhododendron almost any time of year without harming it, but the best time is within a few weeks after it has finished blooming, to give it the maximum time to set flower buds for next year. Waiting too late is no disaster, but could mean fewer blooms for the next year (or a few years if you are pruning it back hard). If you’re doing a major restoration with severe cutting back, the best time is late winter/early spring, before the growing season. Beyond that, avoid extremes of hot (over 85ºF) or cold (under 25ºF) for pruning most plants in our area.

DEADHEADING

Independent of pruning you might want to deadhead (snap or cut off spent bloom stalks). We do that to many flowering plants in order to interrupt the energy normally going into seed production and redirect it toward new bloom buds. Also, it visually cleans them up.

Routine deadheading is fine for younger rhodies, but on a large, mature one, it might not make a significant difference for future blooming. Plus, it can take a lot of time! If lower maintenance is a priority, it’s not always necessary to deadhead.

After blooming: deadheading and optional thinning of new sprouts.

Option to thinning new sprouts: cutting bare branches to activate latent buds.

We mentioned the emphasis on thinning to reduce density and reveal a shrub’s natural form, rather than a lot of heading (or shearing). But thick branches, dense foliage and the interweaving tendency of some rhododendrons call for a bit more patience.

Before and after thinning (and slight heading back) of a large rhododendron.

Before and after thinning (and slight heading back) of a smaller, upright rhododendron or azalea.

After the initial cleaning described in BASICS, you can start thinning, as we say, “inside-out, bottom-to-top, small-to-large.” Work from the inside of the shrub, usually at the bottom, randomly pruning off small branches at their base (where they sprout from a larger branch) and work your way up and out. You can also remove some of the lower branches to help the shrub “float” off the ground a bit more. Then start removing redundant branches which grow through the middle of other dense growth, unless they are major structural branches.

After pruning out several of these, step back to see what difference it is making in the density. You might notice larger branches which could also be removed unless it might create large holes in the shrub’s foliage mass. If there are several major branches crowded together, it’s good to thin out the mass.

Dealing with a tangled, weaving branching habit entails cutting one branch at a time and pulling it out of the tangle.  As you reduce the density, you might also discover long, flexible branches you don’t wish to cut. You can sometimes “reweave” those out from other branches, helping to open up the shrub’s form.

Before and after thinning of a dense (and somewhat leggy) rhododendron.

Can you start to see through the shrub much more than when you started? If not, keep going. When you have one zone of the shrub that looks sufficiently thinned out, then move on to another zone achieve approximately the same density. You don't want to remove every last tiny branch inside the shrub. Thinning aims to improve the transparency of the plant, not skeletonize it.

After thinning the interior, you might still have an outer “shell” of crowded shoots which emerge from near the tips after blooming. You can thin out the numbers of those new shoots (sometimes they snap right off) or, if things are really crowded, cut some of their parent branches further back.

When you feel the whole shrub feels more open (we like to say that it can “breathe”), and not such a dense blob, you can stop! Always better to prune too lightly in one season, than too severely. We advise to not remove more than 25% of the living tissue in any one year.

 

Although heading back outer branches to shorten a plant is easy to understand and seems like a natural way to control the size, it can create a lot of future issues. Some plants tolerate frequent heading just fine, such as common hedging shrubs. But most plants are genetically “programmed” to reach a certain size range at maturity and will expend a lot of growth energy to attain that size.

If you just need to nip back a few long stragglers to clean up your plant, no problem. But if you try to reduce its natural size by more than about 20%, it can react, sending pent-up growth energy into aggressive sprouting. We further describe the risks below.

Shortening a rhody that wants to be much taller often results in a mess of new sprouts!

Rhodies react to heading cuts this way. That can be an advantage when trying to stimulate more leaf growth on a leggy plant, as explained below. But it complicates things if you wish to keep it unnaturally small.

Some rhododendrons can grow into trees 10 feet and higher. If you allow and even train them to reach their potential height through thinning, they can become dramatic, neighborhood landmark trees. There are many wonderful examples in our region, notably at the Rhododendron Species Botanical Garden in Federal Way, and UW’s Washington Park Arboretum.

But an all-too-common situation is a house with a front picture window about five feet above the ground. Years ago, someone (not you, of course!) planted a rhododendron or a group of them under the window for a pretty foundation planting. Either the the information provided by the plant seller suggested the shrub would not grow taller than 6 feet, or that it could grow larger, but that was “after 10 years” or the fine print was ignored altogether. In any case, the rhody is now big and crowding out the window, if not the whole house.

Right plant/wrong place… Reduce size? Remove? Or thin out to become landmark trees?
(photos: L-The Redeemed Gardener, R-The Outlaw Gardener)

Unless you’re willing to significantly thin or remove this giant, the challenge is how to reduce it in a way that doesn’t make the tree look chopped or beheaded. It would be easy to just head it way back, as in REJUVENATING below. But after the initial clearcut, this would likely trigger aggressive sprouting, which can turn it into an even faster-growing, unattractive beast for years to come.

Think instead about redirecting growth energy from the upper leader(s) to lower secondary branches. The method for this is called releadering or drop crotching. Cut a leader branch (tallest one in a branch group) back to a lower side branch (at least half the thickness of the branch you are cutting). Now the lower branch is likely to become the new leader. On a typical rhody there are multiple leaders, so you would releader several of them to shorter branches.

Releadering to gradually reduce height: remove entire branches (rather than randomly heading them back) to transfer the leader growth to lower branches.


On a dense-foliage rhody (or any dense plant), if you shorten all the tallest leaders you will likely open up bare spots — open areas with bare branches and little foliage that were previously shaded out by what you have just removed. In time, these will resprout and fill in but it can take a year or several, depending on the type and vigor of the plant.

With any major reducing, restoring or rejuvenating, we recommend to avoid (if possible) doing this all at once. If you can spread the job over two or three years you might minimize the bare or chopped look and the overreactive regrowth.

For example, you could do releadering on maybe 1/3 or 1/2 the number of tallest leaders, so the top layer is thinned out but not totally removed. Then after a year or two with the lower layers growing in, you can cut back the rest of the top layer. But remember: it may still react to a major reduction over time. Unnatural pruning creates a high-maintenance plant.

Older rhodies can develop quite a leggy habit, especially after years of being crowded by neighboring plants, struggling under dense trees, or just having aged a long time without any pruning attention. Others may suffer low vigor from poor drainage, depleted soil, or other stresses.

Restorative pruning can make quite a difference, along with improving the watering, mulching, and fertilizing of a struggling plant. If the shrub is heavily shaded (unless it’s possible to thin out overhead trees), blooming might always be sparse. And although these methods can help revive most shrubs, some might have deeper health issues and not sprout as well.

A leggy habit is long, tangled, bare branches with few leaves or flowers out on the tips. Restoring a more balanced branching pattern and redirecting growth energy back into foliage and blooming often takes a combination of thinning, untangling/reweaving, and heading back some bare branches.

Restoring a leggy rhododendron with thinning and some heading, to encourage more interior growth.

For long bare branches in the interior that are alive (look for leaves at their ends or use the scratch test described under BASICS), remove any that are causing crowding, and perhaps choose a few to head back, to stimulate their latent buds. Live rhododendron trunks and branches are lined with latent buds (conspicuous or hidden) which often “wake up” when the growth above them is removed.

Combination of thinning and heading back bare branches to induce sprouting and reduce legginess.

If you don’t want to cut off a branch you can try “nicking” the bark just above a latent bud (if the bud is conspicuous). Make a small cut with a pruner blade or small saw barely deeper than the cambium layer. This can “fool” the bud into sensing that the whole branch has been cut, activating new growth.

…OR REJUVENATING ONE

If you feel you must rejuvenate (or renovate) one from scratch, cutting it down to a few primary branches a few feet high will, if it is healthy, cause it to sprout and grow quickly. Late winter/early spring is the season for this. Then you can thin and manage the new branches as they develop using the methods we have described here.

Renovating an old rhododendron from the ground up. (C and R photos: ProperLandscaping. com)

Some gardeners might choose this if it’s an unusual, hard-to-find variety or of sentimental value. Again, consider doing this gradually over two or three years rather than one fell swoop. But if it’s not an exceptional plant, weigh this option with the amount of work (and awkward habit) ahead, vs. just replacing it with a new rhododendron.

There are other shrubs that can be pruned in a similar way to rhododendrons. Common examples include Lily-of-the-Valley shrub (Pieris), mountain laurel (Kalmia), Camellia, strawberry tree (Arbutus unedo), and English and Portuguese laurels (Prunus laurocerasus and lusitanica). These, as well as some popular deciduous shrubs such as lilac, mockorange and forsythia, have latent buds which can sprout from bare branches, so most can tolerate occasional hard pruning.

So the pruning methods we have described apply similarly. On dense or overgrown plants, thin out the inner branching structure, manage multiple sprouts, and reduce or restore plants only if necessary.


Once again, don’t prune your rhododendrons just because “you’re supposed to” but in order to address specific problems and let them be healthy and beautiful.

Still have questions? We are always here to answer your care questions on this or any other gardening needs by emailing [email protected], via social media, or in person at the store!

Tagged: rhododendrons, rhododendron care, pruning techniques, shrubs, trees, pruning shrubs, pruning trees, advanced pruning

How And When To Prune Rhododendrons

How And When To Prune Rhododendrons

Robert L. Furniss
Portland, OR

"How do I prune my rhododendrons?"  The usual answer to this frequently asked question is, "Very little.  Remove the dead and sickly branches and let the plants grow naturally."  Sometimes this is good advice.  It applies best to small, bushy-type rhododendrons and to rhododendrons in woodland and mass plantings, but it is not the whole story.   At times it is adequate, even misleading.

Definition. Pruning is the removal of parts of a plant to control growth.  More art than science, it is an adaptation of natural processes to achieve horticultural objectives.  Broadly, pruning includes the removal of any unwanted parts of a plant, including flowers, buds, soft wood, hard wood, basal sprouts, and sometimes roots.  Pruning is not a routine treatment applied cookbook style.  Nor is it a substitute for requirements for vigorous growth, such as fertilizing, watering, controlling pests, and planting properly.

Objectives. Pruning is for some cultural purpose.  Before plant surgery, the grower should decide what the pruning is intended to accomplish.  Is the grower trying to revitalize treasured old plants, to produce plants for sale, to stimulate maximum number of highest quality flowers, to enhance the year-around appearance of the plants, or to achieve some special landscape effect?  Has something gone awry that needs correcting?  The kind and amount of pruning depends upon the nature of the planting and the purpose of the grower.

Pruning can accomplish a lot.  It can start early in the life of a plant, as in the heading back of nursery stock to achieve compactness.  As the years roll by after planting, many fine rhododendrons decline, become leggy, or develop into brush heaps for lack of attention.  Such plants often can be revitalized and improved by judicious pruning and training.  Of course there are limits.  Medium-sized 'Elizabeth' cannot be forced to grow tall by pruning, and giant-sized 'Loderi King George' cannot be dwarfed.  Most rhododendrons respond well to pruning.  Some that do not sprout readily from old wood cannot be much improved.  Others that sprout abundantly should not be opened excessively to light.  If in doubt, proceed cautiously, or seek expert advice.

When to prune. Pruning of hardened wood can be done at any time except during periods of freezing weather.  Early spring generally is best because the new growth then has a full season in which to develop and mature.   Pruning immediately after the blooming period is standard practice.  However, some rhododendrons that bloom very heavily should be pruned prior to bloom to reduce the number of flowers and thus maintain vigor of the plant.  Thinning the flowers also can improve the quality and placement of the ones that remain.

Summer pruning often results in lush sprouts that are subject to aphid injury and may not harden sufficiently to withstand low winter temperatures.  Deadheading, which is the removal of spent flowers, should be done soon after the flowers fade, taking care not to injure the new growth.  This important job helps control insects and greatly improves the abundance and quality of the next year's bloom.  Soft wood pruning, or pinching back, is done during the growing season.  Removal of terminal leaf buds and shoots to promote branching should be done early in the season or from late summer on through fall and winter.

How to start. A good way to start to prune a rhododendron is to crawl under it, look up, and decide what structural changes are needed.  If the plant has been long-neglected, it likely will be necessary first to cut out a tangle of dead branches.  Then remove cross branches and weak wood.  Remove excess branches to give remaining ones room to grow.  Except when layering a plant, remove drooping branches that scrape the ground and provide handy stepladders for weevils to climb and feed upon the leaves.  Remove spindly shoots that sometimes develop along the bole.  Remove sprouts from under-stock on grafted plants.  These sprouts spring up from the base of a plant and produce flowers of a different color, often lavender.  Fortunately modern hybrids are mostly grown on their own roots, and so remain true to color.  In removing hardened wood, make clean cuts, prune flush with the bole or main branches; do not leave stubs.   Thinning the small outer branches is the final step in the pruning process. 

Pruning for compactness. The compact, profusely budded rhododendrons of the nursery trade usually are the objective of commercial growers and landscapers.  These plants are produced by good cultural methods, including de-budding and summer pruning of current growth to induce multiple branching and abundant flowers.  In the home garden, the day ultimately comes when the branches become too numerous and need to be thinned to restore high quality foliage and bloom.  When this occurs, insect damaged, sun-scorched, winter-injured, and scraggly foliage and branches should be among the first to be removed.  Before planting a rhododendron, keep in mind that it is best to select one that will not outgrow the allotted space.  A tall-growing variety just isn't suitable in front of a picture window.  No amount of pruning will make it fit there comfortably and attractively.

Pruning to a single trunk. In some kinds of landscaping, plants are pruned high and trained to a single trunk or a few main stems.  This treatment reveals the structure of the plant and texture of the bark, thus improving the year-around interest and beauty of a planting. An arched canopy over a woodland-type pathway can be achieved by high pruning of adjoining plants.  The openness of a high-pruned plant facilitates the placement of ladders for deadheading and grooming the top, and provides ready access for watering, fertilizing, and mulching.  If a single-trunk plant is the objective from the beginning, heading back can be delayed to encourage height growth.  Also, while a plant is young and flexible, its trunk can be shaped for character by bending.  If a plant has branched very low or has multiple stems, it will be necessary to cut away some lower branches and all except one or a few of the stems to achieve the desired tree-like effect.   The 'Loderi' and 'Naomi' hybrids and many other large varieties respond well to the single trunk treatment. Bushy varieties do not; for example, 'CIS,' 'Bric-a- brac,' R. racemosum, R. williamsianum, and others.

Pruning for special effects. Sometimes it is desirable to prune a group of rhododendrons so that the foliage on one side is allowed to cascade nearly to the ground and that on the other side is pruned high to reveal the beauty of the trunk and large branches.  Rhododendrons pruned in this way exhibit an unbroken bank of foliage or bloom when viewed from one side and a wooded-dell effect from the other.  The exposed trunks should face the north or east, or be protected from the sun by buildings or other plants.

In general the profile of rhododendron plants is regular.  Individually they are difficult subjects to train for asymmetrical or tiered effects.  These landscape effects can best be achieved by grouping rhododendrons of different sizes and textures, or by inter planting them with suitable companion plants.   However, some azaleas, such as R. calendulaceum, are exceptions to the rule in that they respond beautifully to pruning for irregular effects.

Pruning to rejuvenate. Rhododendrons that have outgrown their site or have become tall, ungainly, and sparse of bloom can be rejuvenated by judicious pruning, preferably in early spring.  Don't attempt to do it all at once.  The plant likely will survive one-shot surgery, even make a strong recovery, but it is no way to treat an old friend.  It is better to spread the rehabilitation over 2 or 3 years.  Each year cut back some of the heavy branches to latent buds.  Let the light in to encourage new shoots to form.  Plants that have deteriorated in the top should be cut back and rejuvenated with new growth originating low on the bole.  Prune with the dual objective of retaining the mature structure of the rhododendron and of improving its vigor and capacity to bloom.

Pruning to salvage. When catastrophe strikes and a large plant is broken or otherwise severly injured, don't despair.  It may be salvaged.  In the wild our native rhododendron, R. macrophyllum, often is killed back to the ground by fire, only to sprout again from the root crown and in a few years regain full vigor.  Cultivated rhododendrons that have to be cut back to a stump likewise frequently recover.

Pruning to facilitate moving. Sometimes large, long-established rhododendrons have to be moved.  This is a sizeable but relatively simple job.  For best results, it should be done in the fall or in early spring before new growth begins.  The roots are cut back (pruned) with a sharp shovel, leaving a wide but shallow pad of roots and soil.  Hauled or skidded to its new location, the plant should be set high in loose, well mulched soil.  To ease the shock of moving, some foliage should be pruned to compensate for the loss of roots.   In part this is accomplished by cutting off lower branches that hamper the moving and in part by pruning unneeded upper branches.  It is a good opportunity to shape a neglected plant.

Pruning azaleas. Most of this article concerns broadleaved, evergreen rhododendrons.  Azaleas require relatively less pruning, but some deciduous ones thrive better if the old shoots are periodically cut back to the ground to give new shoots growing room.  Some azaleas that sprout vigorously or send up suckers from the spreading roots need to be thinned occasionally at the ground to prevent excessive bushiness.  Azaleas can be made more compact by heading back the new growth a few inches in early summer.  Some evergreen azaleas will stand shearing, a practice that is common in Japanese landscaping and which produces very dense mounds of foliage.

Pruning for bonsai. The ultimate in controlling growth by pruning is the culture of bonsai.   Some small-leaved rhododendrons and evergreen azaleas are good material for bonsai.  This specialized aspect of pruning and growing rhododendrons is discussed in "Rhododendron Information," a book published by the American Rhododendron Society, and in standard texts on bonsai.

Treatment of pruned surfaces. It is often recommended that the cut surfaces resulting from pruning limbs an inch or more in diameter be treated with pruning compound. Probably more aesthetic than prophylactic in effect, this treatment appears to be optional with the grower.

Basic tools and references. Basic tools and procedures are discussed in standard references such as "The Pruning Manual" by L. H. Bailey and Sunset Magazine's "Pruning Handbook."  Detailed procedures for pruning rhododendrons are discussed and illustrated in "Rhododendrons of the World" by David Leach.

A final word. In summary, it is a myth that rhododendrons should not be pruned.   The essential thing in pruning is to decide upon the purpose.  Then don't be afraid to apply the saw and pruners to achieve the desired result.  The rhododendrons will appreciate the attention and respond to it. 

 

0005 6 Conclusion

It is hard to imagine anything more like a chic lively bouquet with an abundance of blooming flowers than a rhododendron. These tree-like shrubs will not leave anyone indifferent during the flowering period and are not unreasonably considered rather capricious and fastidious in care. At the same time, trimming rhododendrons is no more difficult than other flowering perennials. Although, depending on the variety grown, these amazing beauties in pruning have their own characteristics and subtleties. nine0003

Is it possible to prune rhododendrons

It is widely believed that rhododendrons do not need pruning, as they are genetically built to strive for an almost ideal bush shape. And many novice gardeners are so sensitive to their promising plant pets that they get scared at the very thought that they need to pick up a pruner and cut something off from the most valuable specimen of rhododendron.

In fact, the experience of many gardeners, who have been growing various types of rhododendrons in their garden for many years, shows that rhododendrons are not only possible, but also necessary. Like absolutely all plants, they absolutely need regular sanitary pruning. Many varieties also need to correct the form of growth. And more mature plants cannot escape from rejuvenating pruning. It can sometimes be replaced only by a complete replacement of the bush. But not every gardener is ready to easily say goodbye to his pet, who has delighted him with his flowering for many years, only because he has completely lost his shape. nine0003

But in order not to bring your blooming pets to such a state, it is better to track all the nuances of possible incorrect growth of bushes every year and help them by forming an attractive crown with the help of pruning.

On the other hand, rhododendrons, unlike many other ornamental shrubs and trees, do not always require mandatory pruning. Indeed, even during transplantation, thanks to a small and compact root system, their roots do not stop their activity for a moment. This means that when moving shrubs with a whole root ball, they do not need the subsequent traditional shortening of the branches in order to balance the "bottoms" and "tops" of plants. nine0003

Why you need to prune rhododendrons

As in the case of almost any representatives of the plant kingdom, rhododendron pruning helps to solve many different problems:

When is the best time to prune rhododendrons

The most appropriate timing for rhododendron pruning depends most of all on the purpose for which this or that procedure is carried out. It is most optimal for most varieties to carry out different types of pruning at the very beginning of spring, even before the buds awaken. In some cases, this must be done in late spring or early summer. Most rhododendrons require special pruning after flowering. Finally, it is allowed to prune in the autumn, before the onset of winter cold. nine0003

How to prune a rhododendron

There is no single standard technique for pruning any rhododendron. The type, degree and even the time interval for pruning is chosen depending on the species (deciduous or evergreen) and the age of the plant.

All existing varieties of rhododendrons are usually divided into the following categories, which differ in the types of pruning applied to them:

For plants of the first group, it is very important to carry out, from the very first years after planting, annual pinching of the tips of young shoots in late May or early June to form a dense and beautiful crown. In autumn, and throughout the season, you can ruthlessly remove all too frail and underdeveloped branches, as well as shoots growing towards the center of the crown. Anti-aging pruning for shrubs of this group can be carried out 1 time in 5-7 years. nine0003

Attention! For a group of shrubs with large leaves, it can be important to wait for bud break and then cut off shoots that have not survived wintering.

For rhododendrons of the third group with small evergreen leaves, shaping pruning is especially important, which stimulates the formation of many young branches. With a strong desire, these varieties can be given almost any shape by trimming. Even form neat attractive "balls" from them. True, this requires a great deal of regular effort and attention on the part of the gardener throughout the year and is best done in warmer regions with mild winters. nine0003

In large-leaved evergreen species, very elongated and bare shoots are usually shortened in early spring to stimulate lateral branching. Anti-aging pruning in large-leaved rhododendrons is carried out no more often than after 12-16 years.

How to prune rhododendrons in spring

In early spring, before the buds swell, they usually carry out:

Under the conditions of the middle zone, this period usually occurs in the second half of March or the beginning of April.

After the main snowmelt, it becomes approximately clear how the bushes endured the winter. Sanitary pruning of rhododendrons consists, first of all, in the removal of completely broken shoots, which are cut off just below the break. If the branch is not completely broken off, then if you wish, you can try to save it. To do this, the fracture site is tied with a polyethylene tape, and the shoot itself is tied to the upper branches or a supporting support is placed. nine0003

In deciduous rhododendrons, during severe winters, the bark may crack on individual shoots. In these cases, it is necessary to cut off all damaged branches to a living place.

Sanitary pruning also includes the removal of dry and frozen branches and leaves. But in many deciduous varieties it is not so easy to identify them before the buds swell. Therefore, you can wait a bit and prune later, after the leaves bloom.

Initial pruning is usually carried out after the purchase and transplantation of young shrubs to a new location. For evergreen types, it is usually not necessary. But deciduous bushes, if desired, can immediately be given an eye-catching shape. nine0003

Spring pruning of rhododendrons is often carried out to form a decorative crown. At the same time, either strongly protruding branches are removed, or those that grow deep into the crown and thicken it unnecessarily. As mentioned above, in deciduous types, it is recommended to additionally pinch young shoots, especially at a young age.

Anti-aging pruning is started when the rhododendron bushes grow so large that they block part of the path on the path or shade the windows of the living quarters. In this case, you should not cut branches that are more than 3-4 cm thick, otherwise the bushes may die. Especially tender are the evergreen large-leaved varieties of rhododendrons. The places of cuts must be covered with a special garden paste or var. Already after 20-25 days, dormant buds may awaken on the branches below the cut and the bush will begin to grow with fresh shoots. nine0003

The next year, the restoration of decorativeness and lush flowering is already possible.

It happens that it is necessary to carry out a strong rejuvenation by cutting branches almost to a stump. In this embodiment, the branches are cut at a distance of 30-40 cm from the ground. But you should not cut the entire bush at once. Deciduous species may be able to withstand such pruning, but evergreens have a chance not to survive it and not recover. Therefore, they usually cut about half of the bush in order to complete what they started next year. nine0003

How to prune a rhododendron after flowering

If you provide rhododendrons with competent and appropriate care throughout the season, they will delight with abundant flowering and fruiting. But it was noticed that in this case the plants have some periodicity in flowering. Because they spend too much energy on the formation of fruits and seeds. If the bushes are grown solely for the sake of lush and beautiful inflorescences, then immediately after flowering they must be carefully broken out or cut off. Usually, a faded inflorescence is taken with two or three fingers and slightly bent to the side. It breaks easily. You just need to look carefully so as not to accidentally hurt the young shoots that form at the very base of the inflorescences. nine0003

As a result, all the available nutrient reserves in the plant will go not to the formation of seeds, but to the laying of new flowering buds and the formation of new shoots. In addition, instead of one, two or three new young shoots are usually formed at the site of the inflorescence.

How to prune a rhododendron for the winter

In winter, rhododendrons are only cut for sanitary and sometimes rejuvenating pruning. In terms of time, it most often falls on the end of September or the first half of October. Depending on the region, this should take place a few weeks before the onset of a hard frost and 2 weeks after the last feeding. nine0003

Pruning of rhododendrons in autumn is most often carried out in order to reduce the height of the bushes and ensure their full wintering under shelters.

Advice from experienced gardeners

In order to get the desired result from pruning rhododendrons, it is useful to listen to the opinions of experienced gardeners who have been successfully growing this luxurious shrub for many years.

  1. After any pruning, even sanitary, rhododendron bushes must be watered abundantly and fed with a complex set of fertilizers. The only exception is autumn pruning. nine0006
  2. It is best to prune the bushes on a regular basis, checking the correct shape of the plants every year. If for some reason the rhododendron has not been cut for a long time, then you should not carry out cardinal pruning within one season. It is better to do it gradually.
  3. When shaping and rejuvenating pruning in early spring, it is very important to feel for dormant buds and cut the branches above them. Sleeping buds are usually small, pinkish thickenings on the shoots and are quite easy to feel with your fingers. nine0006
  4. If rhododendrons have been grown from seed, they should not be pruned at all before the first flowering. Otherwise, it may delay the formation of flowers for another 2-3 years.

Conclusion

Don't be afraid to prune your rhododendrons. For many varieties, pruning is the only way to get beautiful and attractive bushes. In addition, only regular removal of inflorescences helps these beautiful plants bloom profusely every year.

pruning of rhododendrons from A to Z (photo)

Content ✓

Rhododendrons are in many ways special shrubs, unlike most of the crops we are used to. They need a special place in the garden, special soil. And even special agricultural practices. For example, soil mulching is a must, loosening is by no means! nine0003

Pruning in this row is an exception, here the rhododendrons appear in the general formation.

With pruning, they have everything like the others, well, or almost everything. There are, as usual, three types of pruning: sanitary, shaping, rejuvenating.

All that is necessary for this article is here >>>

Read also: Landing of rhododendrons - where and with what: neighbors and companions of rhododendron

Sanitary pruning of rhododendrons

are performed according to wintering results early in spring. We remove the broken branches, carefully cutting the shoot below the fault. Small breaks can be pulled together with an elastic bandage, fix this place and substitute a prop under the bruised branch to neutralize its weight (photo 1). If the branch has broken less than half its thickness, there is a good chance that the break will heal. We leave the support under the shoot for a couple of years. nine0003

Frozen shoots cut out to healthy tissue. In deciduous rhododendrons, in winters with sudden changes in temperature, the bark often cracks. We cut out such shoots to the living. Sometimes it is difficult to distinguish a frozen shoot of an evergreen rhododendron from a living

stem, in which only the leaves were damaged (“burnt”, but actually dried out under the action of the early spring sun and wind). If in doubt, postpone pruning for a while. Soon it will be absolutely clear whether the escape is alive or not. The leaves of a frozen shoot are dry, dull, and fall off easily. “Burned” leaves on a live branch do not fall off by themselves; at the base of their petioles, buds may already be visible, from which new leaves will bloom. So, in photo 2, only a few shoots in the upper left part of the crown have completely lost the rhododendron, the rest will successfully grow. nine0003

Small-leaved evergreen rhododendrons are distinguished by the fact that even a shoot that has completely lost its “burnt” leaves can again completely dress in foliage. Do not rush and cut varieties from this group, unless the affected plant is sitting in plain sight and does not spoil everyone's mood with its condition.

Starter pruning of rhododendrons

As a rule, we buy evergreen rhododendrons in the form of a bush with a beautiful, evenly developed, harmonious crown. Deciduous rhododendron varieties (deciduous azaleas) often don't look as good. They have one or not

how many long, bare and relatively thick shoots with inflorescences at the top and a few short and thin branches. It is better to cut such specimens immediately, trying to give the crown a more or less symmetrical shape (photo 3, 4). Already in the middle of summer, the bush will be much more branched (photo 5), and in the fall you will see that a well-rooted rhododendron has quite successfully laid flower buds over the entire surface of the crown. Thus, we lose in the height of the bush, but win in its shape and quality of future flowering. And such a bush will quickly gain height. nine0003

Formative pruning and pinching of rhododendrons

This type of pruning is carried out either in early spring or closer to the flowering time of the rhododendron, i.e. outside the stage of active sap flow. We cut off unsuccessfully located branches, shorten those that weakly or do not give lateral shoots at all, i.e. naked (photo 6). As a rule, formative pruning is easily possible on bushes of deciduous rhododendrons. Many semi-evergreens (such as the Ledebourg rhododendron and the entire PJM series) respond well to pruning, responding with dense branching and a compact crown shape. With evergreen rhododendrons, it is easy to reduce or narrow the crown, cutting into a well-located branch. nine0003

A convenient technique is to pinch the shoots of deciduous rhododendrons (photo 7, 8). Thus, we shorten a shoot that is too long and encourage it to branch, achieving a beautiful, evenly developed crown shape. The lateral shoots that appear as a result of pinching have time to lay flower buds.

Rhododendron Rejuvenation Pruning

Rejuvenation pruning, like any other, works well on young rhododendrons. After radical pruning, they grow back easily. Another thing is that young people do not need it. If you are a determined person, then do not be afraid to cut the old bush into a stump, i.e. shorten all shoots to 20-30 cm. The timing for anti-aging pruning is the same - early spring or immediately after flowering. But not all old specimens will easily endure such pruning. nine0003

An alternative to planting on a stump of a bush with bare stems, sparse branching, weak flowering and other signs of aging is to replace it. Yes, sometimes it is more rational to replace a bush that has lost its decorative effect, rather than to seek a return of beauty from it with the help of pruning. This is especially true in relation to tall varieties of evergreen rhododendrons.

More densely branched evergreen rhododendrons with a cushion-like habit can often be rejuvenated by pruning. It is performed gradually, shortening up to 15-20 cm by several shoots per season. If successful, buds wake up on old wood and strong young shoots appear (photo 9).

Deciduous rhododendrons can usually be rejuvenated by pruning. In this case, a radical landing on a stump is rarely required, often it is enough to simply reduce the crown by a third or half. In photo 10, a Japanese rhododendron bush, which is over 35 years old.

Learn more