Pruning a smoke tree

Trimming Smoke Trees – How And When To Prune A Smoke Tree

Smoke tree is an ornamental shrub to small tree that is grown for the bright purple or yellow leaves and the spring flowers that mature and “puff” out as if they were clouds of smoke. Smoke trees tend to have a rangy, splayed growth habit. Pruning smoke trees annually will help make the plant more compact and strengthen the limbs.

When to Prune a Smoke Tree

Trimming smoke trees can be done in late winter or very early spring.

As a general rule, pruning smoke trees for shape is done in very early spring when the plant is still mostly dormant and the process will create less stress. Summer flowering trees such as smoke tree need to be pruned before flower buds have shown. The rule for pruning deciduous flowering plants states that if it flowers after June 1, like the smoke bush, you need to prune in early spring.

Smoke tree pruning can also be done in late winter if you wish to rejuvenate the plant and

cut it all the way to the ground.

Pruning Smoke Trees

The method used when trimming smoke trees depends upon whether you want a tree or bush.

How to Prune a Smoke Tree as a Tree

For a tree, you need to start young and remove all the extra stems, leaving only one strong central leader. You can shape it at this point and keep the plant below a certain height.

General pruning will include removing old wood, diseased or broken plant material and managing any suckers and water spouts. Any crossed branches need to be removed to prevent crowding and rubbing.

How to Prune a Smoke Tree as a Bush

Smoke tree pruning for a bush is much less laborious. You may allow the extra branches and simply prune limbs to manage shape. The natural splayed nature of growth can be amended by cutting the plant almost to the ground in late winter. This will force new growth and tighten the overall look of the bush.

When you remove any of the main trunks, always cut to the base of the tree. Very small, unproductive twigs and branches should be removed from the center to create air flow and allow established wood room to grow.

Proper Cutting Techniques

Prior to pruning you need to make certain your implements are sharp and clean to prevent spreading diseases.

When you need to remove a limb or large piece of wood, cut cleanly at a slight angle ¼-inch outside the branch collar. The branch collar is the swelling in the parent branch from which the secondary branch grew. Cutting this way prevents cutting into the parent wood and introducing pathogens.

It is rarely necessary to tip prune when pruning smoke trees, but if removing small amounts of wood always cut back to just before a growth node. This will prevent dead ends and create balance when the node sprouts.

Garden Doctors: Can smoke tree recover from bad pruning job?

Mari asks: When is the best time to prune my smoke tree? A problem occurred when my gardener decided to shear the entire bush into a round blob. Now, how and when do I get it back into its normal growth pattern and shape? Also, I fear I have lost the unusual “smoke” that adds to its beauty.

Smoke tree, botanically known as Cotinus coggygria, does require some pruning to keep it in shape and prevent it from becoming a shrub that can overtake the site where it is planted. Unfortunately, the pruning you described will encourage even more unshapely and rapid growth. But it is a forgiving deciduous shrub/tree that is fairly drought tolerant, has colorful purple leaves (a favorite, ‘Royal Purple’ variety), beautiful fall foliage and is certainly a stunning specimen addition to any garden when situated in a sunny location and given room to grow and show off its qualities.

The best time to prune a Cotinus is in early spring before the sap starts to flow. The timing is important since the sap will attract insects and pruning wounds do not heal readily. How to know if the sap is flowing: make a small cut and if you see a lot of sticky sap, delay the pruning. That may mean waiting until next late winter or early spring.

Pruning in late winter will rejuvenate the shrub, but it will also encourage more new growth than you anticipated. You may have an abundance of new growth after the recent shearing, but still have time to gradually correct the poor pruning in early spring. It may take a couple of seasons to correct the mistake; this is not unusual and applies to many shrubs. After all, gardening is a fun experiment and full of errors, but we have many opportunities to learn and correct mistakes!

Waiting until late winter or early spring to prune will create new flower buds on the plant. Try to identify and not remove the forming flower buds. The billowy pinkish flower clusters in late spring and early summer that appear smoke-like gives Cotinus its common name: smoke tree.

Future pruning goals: Prune to maintain and manage its natural shape. The smoke tree does exhibit a natural splayed or rangy appearance, but that form can be modified somewhat by selective pruning. Open up the shrub for better air circulation; accomplish this by completely removing old stems to the ground (no tip pruning).

Cut out cross branches that are rubbing against each other. Remove all twiggy stems and those non-supporting small branches back to main branches.

Cotinus species and cultivars can vary from 10 to 12-15 feet in height and as wide. Some can reach a height of 20-25 feet. The cultivar ‘Royal Purple’ is a popular selection but there are many other choices.

Judith writes: You recently wrote about Amaryllis bulbs and briefly referred to Hippeastrum, the forced, trumpet-shaped blooming bulbs sold in boxes during the holidays. Mine is healthy and has pushed out a tall stem, but now the stem is falling over. What caused this?

The stalk is hollow and cannot support the multi-trumpet-shaped blooms. Find a small stem or purchase a small nursery support stick, insert it into the soil next to the weak stalk and tie a piece of raffia around the two for support. This should do the trick. Taking care of the problem of stalks falling over early enough (when first forcing the bulb) solves the problem. They are still available for purchase in the garden centers so there is time to enjoy the brilliant-colored blooms.

How NOT to prune a smoke tree

By Laura on August 1, 2014

Not all of our home improvement projects are successful… especially in the landscaping and garden department! Today we’re talking about how NOT to prune a smoke tree, and also some ideas on how we’re going to try to fix our pruning mistakes. Plus a fun surprise twist at the end of the post, so keep reading!

Last time we talked about the smoke tree in our backyard was in May, when we reported on how we pruned it during the winter to try and control its growth.

You can see in the right-side photo above that the tree was looking pretty sparse. At that point in the spring, we weren’t seeing much regrowth and were hoping the tree would fill in more over the summer. Well…be careful what you wish for. Only a few months later, we’ve got a smoky monster on our hands.

Instead of a cute and tidily-pruned smoke tree in our backyard, it’s now growing up as high as the playroom windows. And it’s actually engulfing the little Japanese maple and the ornamental cherry tree and other plants in that corner of the garden. The difference in last summer’s tree growth and this summer’s is crazy – check out this side-by-side comparison.

As you can see, our pruning efforts had the opposite effect that we’d planned. Instead of keeping the smoke tree nicely shaped and at a reasonable size, we seem to have created an even more out-of-control growth situation. The branches and leaves completely block our dining nook window, keeping us from gazing out at the backyard garden during meals. Not cool.

After we noticed the smoke tree’s unusual (and unexpected) growth earlier this summer, John did some more research to see what might have gone wrong. He found this video that details the proper pruning technique for these kinds of large bushes/small trees, and basically we learned that a smoke tree should be pruned in winter or early spring by trimming at the branching-off point, to keep the tree from over-sprouting. John had instead simply cut the branches at their ends, down to the height we wanted the tree to be. He didn’t realize that pruning the tree this way would actually cause its growth to quickly surpass the smaller size we were going for.

Source: Plant Amnesty

In order to make sure this doesn’t happen again, we’re planning to reprune Old Smoky – the correct way – this winter or next spring. We can’t cut it any further this summer, or it will just rebound and continue to get even bigger. So we’ve got to live with this behemoth thing for now. We’re even thinking of changing things up and converting the tree to a bush with a different pruning method. The previous owner tied the tree to a trellis and may have been purposefully training it to grow larger, but we’re definitely interested in a smaller incarnation, so we may try the bush route. (Update: We did it! Check out how we pruned the smoke tree into a bush here.)

There is a silver lining in this whole situation, though. During dinner one night recently at our dining nook table, we were looking out the tree-filled window and lamenting our loss of a garden view, when I saw something nestled among the branches.

Apparently an overgrown smoke tree is the perfect environment for a robin’s nest! This little bird had set up headquarters in a central spot where several branches come together. It was such a nice surprise to discover this, and it made us not mind the big tree so much. We still miss our view of the garden, but this sight is pretty special too.

And, a few days after discovering the robin and her nest, we saw that she had a (very hungry) baby in there!

It’s been amazing to watch this all unfold right in front of our window. The toddler in particular likes to watch the robin’s comings and goings while she eats dinner – it’s a great nature lesson for her. We’re trying to be as respectful as possible and not scare the robin away with our presence on the other side of the glass, but for the most part she’s been more interested in feathering her nest and feeding her baby than with our paparazzi behavior.

Hopefully when we prune the tree in the next several months, the robin will still come back after her winter migration and build her nest here again. We love having her family as our backyard neighbors!

Have you had any landscaping mishaps this summer? Or surprise bird sightings?

(linked at Remodelaholic)

August 1, 2014
category: Landscaping + Garden • Tags: back yard, diy, garden, landscaping, pruning

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17 Comments

  • Julie says:

    I’m not sure what you expected to happen… Most Cotinus is 10-15′ tall at maturity! Instead of fighting it, try putting the right plant in the right place.

  • RobA says:

    Julie, I guess if you had read the post completely, you would have seen that she didn’t the Purple Smoke, the previous owner did. Calm Down

  • Diana says:

    Thanks for your insightful and interesting post. I too am struggling with a smoketree that I planted about 8 years ago. When I originally planted it I had envisioned a beautiful tall tree growing up near the backyard fence to block the view into my neighbors window. It’s had stunted growth due to the almost solid clay soil that we have where we live. (I felt like we were digging out a large clay pot to place the original plant into!) It’s been only 3 1/2 feet tall all this time and I kinda got used to that. In the meantime I’ve planted a garden all around it. It’s taken 8 years for the roots to breakthrough to the adjacent dug out garden and just this year has started to suddenly grow these large long branches on the outer perimeter of the original planting. Now I have to figure out what to do with it!
    I’m not an expert gardener and don’t pretend to be, I have a real day job and try to blog about food in my spare time. But it’s time to do something about this smokebush, which is what led me to your post. Thanks for the useful info!

  • Sodding Cambridge says:

    I have the same issues with smoke trees. I am glad to know that I am not the only one having trouble! haha

  • Sodding Cambridge says:

    It’s really nice before and after pictures with the Robin’s nest. Mama Robin and Baby Robin! Thanks for Sharing. That was gold

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  • Lindi says:

    We have a Smoke Tree which was once a Smoke bush. Help! How did the whacking almost to the ground affect the Smoke?

  • Ann Mullins says:

    I pruned my smoke bush last year by shortening individual branches.
    The result was very pretty early summer with long bouncing shoots with a tuft of foliage at the end and later clouds of smoke floating up and down, up and down . Now, however the shoots are longer and in the wayand trailing. If I leave them they will break off in bad weather.
    What do I do?

  • Scott says:

    Ann, if you have a look at your smoke tree’s limbs, you will see black spots along each limb. Those are the bud sites.
    Trim the limb at an angle about a half inch above the bud site and the plant will start new growth from that bud.

    If you cut the longer center limbs and leave the lower branches, you can get a flourish of purple leaves and still get the smoky flowers.
    Some people like to have a small bush, so they cut all the limbs to the ground level. You sacrifice flowering but get a compact bush.
    I hope this helps.
    The article tells how not to trim a smoke tree, but it leaves out some detail.

  • christina says:

    WOW,,,,HARD TO LISTEN TO THIS

  • Mari says:

    I have a smoke bush that I planted about 10 years ago. I have never hard pruned it, but I will be removing one lower limb to it’s base next spring before it buds. The tree has a nice overall shape which I think was helped by letting it grow so long without touching it.

  • Katy says:

    I have a young smoke tree and pruned it back this winter. Everything in my yard is starting to sprout and my smoke tree looks like a dead 5’ tall stick. I hope I didn’t kill it and it’s just a “late bloomer!” I live in Northern CA Bay Area so climate is mild here. Fingers crossed and hoping for some new growth! Any advice appreciated.

(Answer)

When looking at the photo of your Smoke Tree (Cotinus coggygria) enlarged, it appears to be the green, rather than the purple, variety. According to the Connon Nursery catalogue (2009), it has reached about its maximum size; 3.5m high, and 3 m wide. Some of the varietals, such as “Royal Purple” or “Young Lady” are smaller, with a mature height and width of 2.5 m. Either way, this species has a rangy growth habit, and should be pruned yearly to maintain a more compact shape. As your smoke tree is mature, and has multiple branching low to the ground, it is really a shrub, and should continue to be pruned that way. Choosing a leader to encourage growth as a tree now, is not recommended.

Smoke trees are a summer flowering shrub, that is, produce flowers on new growth. That means they should be pruned in the late winter or very early spring, while dormant. One advantage of pruning at this time is that the shape and branching can easily be seen. All good practices in pruning start with removing dead and broken branches with a clean, sharp secateur or lopper. If the branches or trunks are large, use a clean, sharp pruning saw. Next, if there are crossed branches rubbing each other, gauge which branch is best to keep, and remove the other one. Rubbing branches can introduce pest and disease. Now also is the time to remove weak branches, suckers from around the tree, and any water sprouts – those long branches that stick straight up and don’t branch on their own. When pruning any shrub, always cut to about 1cm from a growth node, or where buds are evident – that is where the new branching will occur. If it’s a trunk or large branch cut only to where the collar of the branch meets the main stem.

Next, decide how high you want to maintain this shrub. Branches can be pruned to that height over the next two years. Chose half the branches to prune this year, from all areas of the tree (that way is doesn’t look lopsided after pruning) and cut them to a growth node below the approximate height you want. Next year, these branches will have grown, but the branches left alone can then be cut back to the desired height.

Now the entire shrub is at the height you prefer, and should be maintained yearly to that height. This article also suggests that if the smoke tree is too rangy, it can be pruned to just above the ground in late winter, to maintain a tighter growth. I have done this with other shrubs, such as dogwood, to good effect, although I have not done this with Cotinus.

Cotinus coggygria “The Smoke Bush”

Cotinus requires little or no pruning which makes it easy to grow. In late winter/early spring around February/March time a light prune can be undertaken if needed to remove diseased, spindly or crossing branches and then a feed is an option. Equally Cotinus can be left for several years with little or no attention.

Cotinus when grown in its preferred conditions can be vigorous and get large. This means it may outgrows it allotted spot or is overshadowing neighbouring shrubs and plants. If this occurs, Cotinus can be hard pruned if the shrub is mature and it will tolerate being cut back hard or coppiced and this will keep it in check although at the expense of flowers. Hard pruning will also have the effect of producing larger leaves that year. Cotinus will respond well to clipping and I have seen it grown to good effect clipped into a round lollipop shape, which makes a nice contrast from green topiary. Winter is the best time to prune or trim Cotinus, around February when the shrub is dormant and during a mild spell.

If Cotinus is not the ideal shrub for your garden, check out shrubs and bushes; spring flowering shrubs; summer flowering shrubs; shrubs with autumn and winter interest; and evergreen shrubs.

Cotinus comes into leaf late in spring but the compensation is the great autumn colour. Cotinus looks good with many border plants, blue and pink Clematis, with vibrant greens, as in the image centre which is with Alchemilla mollis, and with strong blues such as Agapanthus and good with Crocosmia; and also with other garden shrubs by way of contrast as in image top left with Cornus.

Cotinus is fully hardy and easy to grow. The new foliage in spring looks lovely and particularly beautiful with raindrops on it. Late summer the shrub, if provided with enough warmth and sun, will flower producing the delicate smoke effect and then put on spectacular autumn colour; a great garden shrub.

Cotinus coggygria — Smoke Tree

One of the more fanciful sites in the summer garden is a smoke tree in full flower. Individual tiny blossoms in airy, filamentous panicles appear wreathed in clouds of smoke. This unusual display, combined with striking foliage, makes Cotinus a wonderful accent plant or addition to a shrub border.

Smoke trees are deciduous, leafing out mid-April in Sonoma County and dropping their leaves in mid-to-late December. The intervening eight months begin with vibrant new foliage, followed by an arresting floral display, colorful post-flowering foliage, and stunning fall color.

Trouble-free, cotinus grows in most any type of soil in full sun to part-shade. Foliage color is generally better and brighter with more sun; in hotter inland parts of the county, some afternoon shade may be helpful. It thrives on regular garden water for a year or two after planting, but requires only low water once it has become established. No insects or diseases are known to cause problems.

Despite the common name of smoke tree, cotinus naturally grows as a large shrub, reaching 15 ft. high and wide, arching to the ground if left unpruned. But because it is amenable to all kinds of sculpting, it’s possible to create a smaller shrub or a small tree.

To form a globe-like bush, every year in late winter or early spring before bud break, cut all stems to 6-12 in. above the ground. The result will be large, gorgeously colored foliage at eye level for easy viewing, but no flowers will appear as Cotinus blooms only on old wood—that is, at least a year old—which has been removed. By pruning severely every other year, the plant will still be at manageable size and flowers will bloom on unpruned branches.
To create a small tree, single or multi-stemmed, wait until the plant has been in the ground for a couple of years, then begin to limb up the shrub. Select one to three stems that will become the single or multiple trunks of your small tree and remove other lower branches. Continue to shape this way until you arrive at a satisfying tree-like shape. You may need to remove lower and interior branches that appear annually.

There are many different Cotinus cultivars available in the nurseries. ‘Grace’ has huge, maroon leaves and spectacular fall color that turns a deep salmon pink, but branches may become unwieldy or unshapely. ‘Ancot’ has chartreuse leaves that turn yellow in autumn and is sometimes sold under its patented name ‘Golden Spirit.’

The species Cotinus obovatus is more treelike with slightly bluish green leaves that turn stunning colors of orange, rust and yellow in fall. ‘Pink Champagne’ has pink flowers.

September 2019

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