Time to Prune Cherry Laurels (Azaleas, too)

'Otto Luyken' Laurel

by Gardening Coach Susan Harris

Lots of homeowners are looking for evergreen shrubs to cover up the foundation of their house, or to create screening and privacy from their neighbors.  That may be why cherry laurel (Prunus laurocerasus) is so popular with landscapers, whose job it is to find plants that do all that reliably, and why I recommend it so often myself.  It even comes in a choice of heights for seemingly every situation and given good light, they grow pretty fast.  Their white blooms in springtime are fragrant.  They’re what you might call do-ers – plants that perform well in the garden for many years.

The ‘Otto Luyken’ variety grows to 3-4 feet tall and 6-8 feet wide and as you can see in this photo of my house, it’s short enough to not block first-floor windows.  Another popular choice is ‘Schipkaensis’ or ‘Schip’ , which reaches 4-5 feet tall and 5-8 feet wide.   There are lots more varieties that reach from 10 to 20 feet, like the very old hedge in the next photos that runs along the side of my back yard.

Renewal pruning is counter-intuitive

This one grows to 15 feet tall.

First I have to confess to pruning my cherry-laurel hedge all wrong for its first 15 or so years.  When it got taller and wider than I wanted it to be, I started shearing it across the top and the sides, and after years of that treatment the shrubs gradually became leggier and infested with pests of all sorts.   My pruning technique had created an encasement around each plant that kept air, light and water from entering – all enticements to disease.   And aesthetically, the shrubs no longer had the fullness and natural shape that was the point of planting them in the first place.   And by the time I realized all this, the hedge was full-grown and not something I could easily replace even if I wanted to.

So I started attending pruning lectures (including one excellent talk by our own Gene Sumi) and reading books on the subject, and proceeded to begin the process of renewal and renovation that’s brought them back to health and allowed them to be their prettiest, too.   This technique can (and should!) be used on dozens of old and overgrown shrubs that are commonly seen in the garden that really could look so much better with just a bit of effort.   Some that come to mind are azaleas, viburnums, forsythia, mock oranges, and forsythias, all of which can be pruning now through the end of June.   Spireas also benefit from renewal pruning and the early bloomers are ready for the pruners now; late bloomers like ‘Anthony Waterer’ will be ready in a week or so.

Cherry laurels in bloom.

So here’s how to renew these old, overgrown and often misshapen shrubs.  Each year for three years, simply  remove one third of all the stems down to their origin (yes, close to the ground).  I call this counter-intuitive because really, who’d ever imagine doing it?  And when I suggest this to clients, disbelief is written all over their faces.   I usually make the first cut myself just to demonstrate how easy it is to remove large stems and how immediate the reduction in crowding.   My hedge here grew back and achieved the height and shape I was after in about five years.  Gardening sure teaches patience, doesn’t it?

Now to touch briefly on azaleas – because they’re even more common in our region and even more likely to be old and overgrown.  When I bought my lot it included some 8-foot-tall azaleas that had strained to get more sun for years and become quite leggy.  This same renewal pruning technique worked just as well for them and they’re now round, full and healthier than ever.

Cherry laurels as hedge, with azaleas, nandinas and hostas.

Regular pruning

So how do you keep these shrubs pruned for good health and beauty?  Once they’re full-grown or close to it, all of them benefit from a quick annual pruning that includes:

  • Removing all dead, dying and diseases branches and stems – back to where they start.  (Never cut just anywhere, leaving a stump.  Cut a half inch above a branch.)
  • Removing at least one of the oldest stems back to the ground or close to it.   This is often the tallest of the stems, and almost always the thickest and showing age in color – usually grayer.

That’s it.   I also regularly remove stems that are lying on the ground, often called “limbing up”.  Too much limbing up can ruin the natural shape of the plant, so I remove just the limbs that are smothering groundcovers and hiding weeds, especially those viney weeds that can totally enshroud the poor plant before you know it.

9 Responses to Time to Prune Cherry Laurels (Azaleas, too)

  1. Ellen says:

    “Removing at least one of the oldest stems back to the ground or close to it. This is often the tallest of the stems, and almost always the thickest and showing age in color – usually grayer.”

    I must confess that I’m confused by this. My laurels have a main trunk with many branches growing out of it, but maybe I just haven’t really looked at them lately. I guess I should be picturing a lilac- or mock orange-type growth habit. Our laurels are in need of some shaping, and if I hadn’t read this column, I would have done exactly what you described in the beginning, so thanks for posting this.

  2. hb says:

    Yes, my question as well…what do you do when there is one large central leader and stems (mostly dead) coming off of that leader?

  3. I’ve never had a cherry laurel with just one central leader, so I’ve asked Homestead’s Gene Sumi to weigh in.

    Gene?

  4. Gene Sumi says:

    This shrub is normally much more branched and full, where the energy of the plant is diversified over many smaller branches and not concentrated on one major one. You will see a dominant leader on the Schipkanensis variety, which has an upright form and should be taller than it is wide. You would normally want to correct this extreme leader dominance on a dwarf ‘Otto Luykens” by cutting off the top portion of that leader to encourage side branching which should start the plant off on a course of diversification of energy through the side branches that are formed by this pruning. You don’t need to cut off very much to make this happen.

  5. Patrick Lally says:

    Hi — this pruning advice is very helpful, but before I start, there are sections of my cherry laurel hedge row where the leaves are turning yellow, falling off, and ultimately causing the affected branch to die off. The plants are about ten years old and very well-established, in fact, this season the fruit was heavy and abundant. But I’ve noticed this yellowing for two seasons now. The plants are also looking a bit thinner than normal, even where the leaves are still green and glossy. Would you have any idea as to what’s going on? They used to look great and now in a relatively short time I’m worried I might lose them.

    • Gene Sumi says:

      If entgire branches eventually die after displying yellowing of the leaf color, you may have one or both of two cherry laurel pests that display these signs. One is Phytophthora cinnamomi, a root rot that is caused by a species of soil-dwelling fungus. The die-back of branches is random and progressive, usually one branch or a section of branches at a time. This happens in the summer when the soil is warmer. You can control this pest by drenching the soil around the shrub’s roots with a solution of Agri-fos Fungicide mixed with water. Apply twice, the follow-up application 30 days after the initial one. I advise treating all other cherry laurels to prevent the start of this disease. The die-back of branches could also be caused by an insect, the Peach Tree Borer. This caterpillar tunnels under the bark and eats away the living Cambium layer. This cuts off water from the roots to the branches, causing the branch to die. This occurs in late spring/early summer. Treat this pest problem by spraying Bonide Borer and Leaf Miner Spray on the bark on major stems that enter the soil. The borer is found boring at that point where the main stem enters the soil. Dig the dirt away and spray the insecticide all around the base, just above and just below the soil line. Again, both these pest may kill the entire plant if allowed to continue without controls applied.

  6. susan harris says:

    Patrick, I asked Homestead’s guru Gene Sumi your question, and here’s his answer:

    This person has given some good information. The plants having yellow leaves at the end of summer is normal for most evergreen broadleaf shrubs. Evergreen broadleafs keep their green leaves for a long time, and although they don’t get rid of all of them in fall, they use this time when they do not need all of the leaves that were made and used during the spring and summer to reduce a large number of leaves now excess with the shorter, less active days of the coming winter. This person should expect to see more yellow leaves and subsequent leaf loss appearing low on the branches and in the center of the plant. These are the older leaves on the shrub and are the most expendable to the plant. They will show the stress damage of the preceding growing season more than the younger leaves near the tips of the branches. So, the yellowing and thinning of the leave cover on evergreen broadleaf shrubs like the cherry laurel is normal and expected this time of year.

    About the branch eventually dying off: Cherry laurels are subject to branch dieback during the growing season for several reasons. First, physical breakage low on the branch. Second, overwatering. Third, damage from the Peach Tree Borer. Lastly, root damage caused by Phytophthora Root Rot fungi. The damage by reason 1 and 2 can usually be determined right away. Peach tree borer damage can be determined by moving mulch and soil from the base of the shrub’s main trunk and feeling the trunk at the soil line. Root fungus damage is determined by signs and symptoms: occurs in summer, soil has been overly wet for several days, the die-back is progressive, i.e., individual branches die quickly, one by one or in groups, while the remaining branches of the shrub appear healthy and green

  7. William Brown says:

    I have two Schip Laurels close to the side of my garage. They are about six feet high. I took out a couple of larger branches this Spring just after flowering. Since then they have exploded and I have a lot of new growth. I want to train them upward…not sideways. Any general tips on pruning Schip Laurels such as when and how much? Thanks. BTW, I’m not much of a gardener, so keep your answer as simple as possible.

    • Susan Harris says:

      William, you can prune your Schip laurels now through late summer. Here’s what I do to train shrubs upward, not sideways. Simply remove completely any branch going in the wrong direction – sideways. Make the cut where the branch starts back on a main stem. The idea is “Don’t go there!” I do the same with any branch heading in a wrong direction, including into the center of the shrub, where I’m trying to keep it open to light and air.

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