How To Prune Boxwood

How-To's, Landscape Care · Written by Roger

158 Comments

Boxwood happens to be one of the most common plants around, especially if you consider all the varieties there are.  I certainly don’t mean common in a negative sense.  Boxwood and all its varieties often serve as the backbone to many beautiful (and functional) gardens.

To Shear or Not To ShearSheared boxwood before

With Boxwood most people instinctively shear the plant.  The vision most of us have is one of perfectly shaped forms.  It definitely is at the top of the list when it comes to formal gardens and topiary.

I’d like to suggest two circumstances when “selective” pruning might be the alternative to shearing.

  1. when boxwood is used in “natural, informal gardens”.
  2. when boxwood starts to decline because of too dense branching at the outer ends of the main stems.

Boxwood used in natural, informal gardens.

It’s such a reliable, solid performer; I often use boxwood in natural settings.  In these gardens the boxwood are pruned selectively by hand to encourage the plant to stay full and strong while keeping a soft, mounded shape.

Dense, outer growth causes decline.

Overtime a constantly sheared (and formal) boxwood can start to decline in health.  This could be because of a number of conditions, e.g. poor internal air circulation that could promote disease or insect infestation.  The fact is plants naturally are not conditioned to have all their foliage concentrated just on the outer portion of the branches.

To improve or maintain the health of a sheared plant, you can selectively prune out a portion of the dense, outer growth.  If done right this will allow more light and air into the interior without causing a dramatic change in the look of the plant.

sheared boxwood afterTopiary Boxwood

I’d like to focus on shearing because this is by far the most common way people prune boxwood.

These first 2 pictures show the before and after of a Boxwood ‘Wintergem’ that was sheared.

This is a recently planted boxwood that was sized at 24 – 30″.   At this young stage you have the perfect opportunity to set the proper shape for the future of this plant.  Although you can often correct misshaped plants, it’s not easy and usually takes 2 to 3 seasons of growth to see improvement.

The fundamental rule in shaping a plant is wider at the base and taper towards the top.  There are 2 main reasons for this:

  1. It’s healthier for the plant because light is better distributed to the foliage.
  2. Aesthetically it’s more attractive and logical that the plant be wider at the base.  You want the plant to appear as though it’s connected and well-anchored to the ground.

In the sketch below I give a couple of typical shapes you would shear plants both the “right” and “wrong” way.

sheared plants right and wrongIt is not easy to develop these proper shapes with wider bases.  Plants naturally grow a little weaker and thinner towards the bottom.  Also, it’s been my experience that most people want to cut an equal amount off the plant all over.  That doesn’t work!

If you look at the first picture of the unsheared boxwood, notice how the greater amount of growth is concentrated towards the top.  The bottom and lower sides naturally have less growth.  Now look at the plant sheared in the 2nd picture.  The lower portion of the plant was not touched by the shears.

handshearsI still happen to use a pair of hand shears for trimming topiary plants.

You should develop a system or pattern to how you shear a plant, get good at it, and then repeat that pattern from plant to plant.

I shear plants in a clock-wise direction.  I imagine the proper line the shrub should have and follow it.  Regardless of how much or how little foliage there is, stay on that imaginary line. If you need a little help and guidance, for the straight lines take a length of wood like a 1 X 2″ (or anything like that).  If you just hold it up once in a while to show the line you’re trying to create, it can really help guide you.

gas hedge trimmerYou more often see power hedge trimmers today for shearing topiary plants.  They are powerful and quick.  If kept sharp and in skilled hands they can do some nice work very productively. In unskilled hands…I’d rather not talk about it.

When to shear plants.

Generally it’s best to let the new growth finish and “harden off” a bit before shearing.  From a practical sense the plant should not grow much (if at all) after that and the shape should stay nice until the following growth season.

If you happen to trim early, occasionally I have seen new, soft growth scorch a bit if the weather got hot right after the shearing.

On some properties plants might be sheared twice because the owner does not want to wait for the growth stage to completely finish.  So it’s done perhaps midway during growth and then again when it’s finally finished.

These are the main considerations when pruning boxwood and many of these points apply to other plants as well.  However, it’s so important you consider each plant and their “specific” preferences and requirements.  Like so many things, the skill starts with the right knowledge.

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    158 Responses to “How To Prune Boxwood”

    1. Judith Rudge Says:

      Hello Roger
      We have just taken on a Victorian walled garden in Scotland with about 300 metres plus of overgrown, very old, box hedging that needs renovating and reducing in size to restore it.
      I was advised to take a hedge trimmer to it to do the job. I started on a small length of about 20 metres (using shears) and find that the centre of the hedge seems dead and now it looks very ugly. I have stopped doing anything to it until I find out what to do next. The outside of the hedge seems very healthy without gaps and spring growth is coming through very well on all but the top/middle of the trimmed length. Can you advise me of the best way forward? Thank you.

    2. Roger Says:

      Judith,
      Of course it’s difficult to give specific advice without being on-site seeing the plants.

      Boxwood will rejuvenate from hard pruning, but I’d go about it differently than using a hedge trimmer exclusively. I’d use a combination of hedge trimmer and hand-pruner.

      I’d use the hedge trimmer to do an overall aggressive trimming, but not so aggressive as to expose bare stems. Then, with the hand-pruner I’d begin to thin the plant to get more light and air into the center and lower portions of the plant. This will begin to encourage budding and growth in the interior.

      Each season (early spring) you would repeat this strategy. Gradually you can reduce the overall size while removing more older stems and letting more and more light in as the plant produces more growth at the interior.

      Here is an excellent article on pruning boxwood and describes the general concept I’m suggesting.

      Hope this helps.

    3. Marina Heneghan Says:

      Hi Roger,My neighbour has given me some plants that are about 2ft to make a headge at the front of the house..In his garden they were all bunched together..now I’m trying to get a nice straight hedge with them but they are very bare at the bottom till about a 10 inch up..Also they are very straight so I’ve put sticks in to support them..Should I just leave them alone for a while to get used to being in a different place?or should I trim the tops of now? Although, this would probably leave a lot of bare wood…thank you..Marina

    4. Roger Says:

      Marina,
      At this time I would prune the tops a bit. You still want to leave plenty of foliage so the plants can utilize that foliage to manufacture food for themselves. But simply removing an inch or so at the top sends a message (and energy) to the lower portion of the plant(s) to push buds and growth down there.

      Next early spring (2018), before growth starts, you can prune harder if you wish. The idea is to consistently prune (year to year) to encourage lower growth. In my experience, this can take time — sometimes several seasons. But with persistence you’ll be amazed how they fill in and get stronger/sturdier.

    5. Jo Laffey Says:

      Our boxwood were planted in mid-May and are growing “straight up.” They have grown several inches. I’d like to give them a gumdrop shape. When is the proper time to shape them, and do you have suggestions for the process?We live in southern WI. Thanks.

    6. Roger Says:

      Jo,
      There are quite a few different varieties of boxwood and their “natural” growing habit/shape can be different depending upon the variety. In turn, not all boxwood can be shaped as “gumdrops”. :-) Do you know which type of boxwood you have? If you do, then do a Google search for that particular plant and view the images to see how they naturally grow.

      It’s now June, and depending on where you are it may be too hot to prune now. I’d wait till late summer/early fall and do a light trimming. Then, in early spring (2018) I’d prune again — and this time of year you can be more aggressive with your cuts.

      As far as the process goes, follow the tips and suggestions in the article. If you feel you need even more information, here’s an excellent article on boxwood pruning.

    7. Janet Priore Says:

      My mature boxwood plants normally grow in even, bushy patterns a few times per year. This year, they are sprouting new growth in tall, sparse patterns. The plant seems to be healthy overall, but I’m concerned that something isn’t quite right. Any advice?

      I’m trying to include a photo, so hopefully it will explain things better than I can.

    8. Roger Says:

      Of course it’s hard to say why your boxwood have chosen to grow this way this year. There are numerous factors that could be at play here. The fact that the plant appears healthy may indicate that there’s nothing specifically wrong, but that environmental conditions (i.e. weather, temperature… that sort of thing) are the cause.

      I’d keep an eye on them and look for other extraordinary changes. If things continue to look normal my guess is the boxwood will have a more normal growth pattern next season.

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