How To Prune Boxwood

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

79 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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    79 Responses to “How To Prune Boxwood”

    1. Johnny Says:

      Hello Roger,
      Great write up, now I know how to trim these for my first time, Thank You.

      I had seen above you stated to “subscribe to my articles via e-mail or RSS”, So I hope this message reaches you.

      Here is my problem, my township decided to spray a brine solution not only in the street but 5 to 6 feet past the curb, and that has damaged 43 of my 97 Winter Gem Boxwood’s that were just planted this past September, the 43 be closest to the street, I did not notice the spraying until today, I was concerned as to the coloring of the Boxwoods the last few days, But then this evening I noticed the white film sprayed about 7 feet into my driveway, So even though it is 35* out right now I am hosing them down and watering them 12 at a time via sprinkler, is this the right thing to do, my neighbor says yes but then I have read that Boxwoods do not like a lot of water at this time of year, my neighbor states that I should water them for many hours to clean the soil and roots.

      So you know my climate I am in Montgomery NJ .

      Thank you,
      Johnny

    2. Roger Says:

      Johnny,
      I’ve not found Boxwood on any list of salt tolerant plants, so it’s good you’re aware of the condition and trying to mitigate it.

      I did a little research and came across this great article from the CT Agricultural Extension Office. It describes the condition of excessive salt and gives recommendations on what to do about it. Leaching is a help, and if your soil is no longer frozen and drains well, that appears to be a good thing to do. Spraying and washing off the foliage is advised too.

      And you could also add gypsum to the surface to help neutralize the salt.

      I’d think about sending a soil sample to Rutgers. You can get a soil sample submission kit from your local Agricultural Extension Office. If you do, make sure you specifically request a “salinity” test. With the test results you’ll know exactly where you stand. And often they’ll include recommendations along with the analysis.

    3. Johnny Says:

      Hello Roger,
      Great write up, and thank you for your help.
      Johnny J J

    4. Pat Says:

      “Hi” Roger – “thanks” for the helpful info on Boxwood.

      I have a different problem with Boxwood; I have two boxwoods each in a large container … they have turned a yellowish color and with this past winter being a very long “cold” winter (OH), I’m wondering if I’m losing them. One has always been a little more “yellow” (would Iron help?), but I was wondering if I could cut them back for new growth – would this ruin or help them become greener? What type feeding would you recommend Boxwood in containers?

      Appreciate your expertise.

      ~ Pat

    5. Janet Bolton Says:

      In Wisconsin my boxwoods had about 6 inches of bright yellow color this spring. Is it necessary to prune all the way back to only green stems?

    6. Teresa Says:

      I have boxwoods in front of my new home of 1.5 years. The boxwoods were trimmed incorrectly before I ever moved into the house. They are like picture 2, I would like for them to have a round shape or a square if round is too hard to get now. How do I trim them so that they take on that round shape or do I hard trim the top to more of a square?

    7. Roger Says:

      Pat,
      It’s been my experience with Boxwood in planters that after a few years they’ll likely need to be changed-out. I think you can prolong this by making sure your planters are slightly elevated so they drain properly. And feeding a couple of times a year with a general purpose liquid fertilizer is smart too. Of course a watering routine is also important.

      We sometimes use various evergreens in planters and the look is great. But realize these plants are now subjected to conditions that are way different then what they naturally prefer. The planter confines and limits root growth. It fluctuates to the extremes of temperature – unlike the ground. It’s likely to dry out and stay dry for longer periods of time (unless irrigation is provided).

      And when these plants are weakened and stressed because of these less-than-ideal & unnatural conditions, they’re more susceptible to insects and other problems.

      Sometimes what we’ll do with these plants when they seem to be getting “tired” of the planter is transplant them into an ideal spot in the garden and see if they recover.

    8. Zulfar Shaker Says:

      hello,

      I wanted to plant a couple of Japanese boxwood into two planters that we attempted to grow gardenias in (however didnt do well). the planters have azalea soil and I am hesitating on whether or not to remove and replace with regular potting soil before placing the boxwoods? will the acidic soil hurt it?

      Thank you,
      Zulfar
      San Diego, CA

    9. Roger Says:

      Janet,
      I’m presuming that yellow foliage is on last year’s growth. And it’s probably due to the winter conditions we had.

      Check to see if those stems are green (alive). If they are I’d wait and see how the plant reacts with new growth this spring.

      It’s doubtful the yellow foliage will change color wise, but perhaps new growth will push out and hide that.

    10. Roger Says:

      Teresa,
      By picture 2 you’re probably referring to the diagram and the second image from the left. I’ve been able to correct many shrubs that were shaped wider at the top by consistently pruning/trimming just the top portion, and not the lower.

      By imagining the proper line (shape) the plant should have, you focus your trimming where the growth is heavy and let the shears just follow the imaginary line. If there’s nothing to cut where that imaginary line is…so be it. This is where people go wrong – they believe if they take 2″ off in one spot, they should do the same throughout. Many plants naturally will grow less towards the bottom. You, therefore, have to follow the imaginary lines of the proper shape to get that “wider at the base” look.

      It may take several growing seasons for the lower growth to catch-up and fill-in to get the correct shape.

    11. Bonnie Says:

      I live in Wisconsin and have a rather large planting area that needs to be re-done due to foundation work we had done. I am interested in adding a few Baby Gem Boxwood to the area in question. The area has an eastern exposure and the only direct sunlight it gets is in the early a.m. hours. We also have a large Maple tree that blocks the mid-day sun. I’m wondering if you think it will receive enough light in this location? I prefer to keep the shrubs smaller by pruning instead of letting them grow to their 3′x3′ potential. Will the presence of primarily shade throughout the day inhibit the health of the shrub or just the extent of its growth every season? The area I have to re landscape is about 4′deep by 20′ long. Have you any other suggestions for shrubs, maybe even flowering types, that can be put there that will not grow too tall (over 4′) but will still help fill in this rather large area of space. I am planning to also plant shade-loving perenials and annuals to fill in between any shrubs that I do plant.

    12. Roger Says:

      Zulfar,
      For boxwood you want more of a neutral soil pH (6.5-7.5). It’s likely the azalea soil you have is acidic. Of course a soil pH test would confirm that.

      But if you’re unsure, I think it makes sense to change out the soil to the standard potting soil. I wonder if soil analysis (like pH) is listed on the bagged soil. You would think it would be. Soil pH test kits are inexpensive, and you can find them on Amazon.

      Remember too that boxwood prefer (demand) well-drained soil & conditions. Make sure the planters drain well, and elevate the pots slightly off the ground or surface. People neglect to do that and the planters can not drain properly.

    13. Roger Says:

      Bonnie,
      The boxwood would likely be OK in that area/exposure, but you should expect it to grow slower and thinner than if it had more light.

      Another plant to consider would be Azalea yedoense ‘Poukanense’ Compacta (or Azalea Poukanense Compacta).

    14. Shannon Says:

      My mom is having issues trimming her boxwood — she says the cut leaves turn white and the bush looks pretty awful. She says it takes all summer for the otherwise very healthy plant to look good again. She lives on an island a couple of hours south of Seattle. The boxwood is about 12 years old and usually a nice glossy green with no signs of disease. She’d like to be able to trim the height of it because it lives just beyond the edge of a deck and is starting to encroach. Thoughts? Thank you!

    15. Roger Says:

      Shannon,
      I’m not quite sure why the trimmed leaves turn white. Perhaps the cut edges are scorching a bit from sun and heat.

      We avoid pruning the new growth on boxwood as hot weather approaches. Once the new growth matures and “hardens-off,” then we can start trimming again. For example, here in the northeast it’s around August when we confidently trim boxwood after its seasonal growth.

      Alternatively (or in addition) we prune boxwood in the early spring before new growth starts.

    16. Josie B. Says:

      Dear Roger,
      I just bought 26 Common Buxus Boxwood Treelings from Walmart. Its now mid July. They are about 1 gallon containers and the plants are about 8 inches tall. I thought I was familiar with boxwoods but now after all my new reading/research I feel clueless. My question is, should I plant now or wait until Fall? What should I do with them to keep healthy if I wait for another 2 months? Also, how far apart should I plant them if hedging? I’ve read as little as 6 inches to as much as 1/2 its width which according to the label is 3-20 ft. How should I know what is its true width/height if the label says 3-20 ft? Last question, I’m reading that they are slow growers but others say fast. Will these small 8in treelings ever become a hedge in my lifetime? Many thanks and sorry for the long write up.

    17. Josie B. Says:

      Roger Josie here again. I forgot to mention in my earlier write up that I’m in Zone 4b Canada, Quebec. Will my baby boxes live in this zone? I have the common boxwoods from Walmart (8 inches)? How far from the road should I plant them if they grow to be 3 – 20 ft wide? The snow plow guy piled about 5 ft of snow on the side of my yard from the street. Don’t know if it was salt or just the black pebbles. What should I do to protect the little guys. Its only mid July but I want to definitely be prepared.

    18. John Says:

      Hi Roger
      I live across from Seattle WA (zone 8b) and have an old established boxwood hedge (>55 yrs. old). The hedge is about 45 inches tall and 36 to 48 inches wide across the top (depth) and generally narrower at the base but tending to be more straight up and down the sides. > I bought this house about 23 years ago and the hedge had the same general shape then though infrequent missed pruning’s may have allowed it to grow wider. I have never felt good about trying to change the shape to the ‘tapered top’ look since it will make the sides completely bare at the top. Allowing the base to fill out is not an option. The hedge does look good after I prune it, but I don’t really like the size and would like to gradually trim it back to a more reasonable depth (mostly to reduce the yard waste but also to allow deer to jump over instead of thru it). Any suggestions for how to proceed?

    19. david Says:

      Thanks for the excellent article and the helpful answers. It’s Sept. 17 here in a NW suburb of Chicago and I’m wondering if it is too late to prune back the boxwoods. Our first average frost date is, I believe, Oct 15. The earliest we get frost could be Oct 9

    20. Roger Says:

      David,
      If you’re able to I’d wait until spring. There are stored carbohydrates in the plant that you’d rather not reduce before heading into winter.

    21. Julia Says:

      Hi, Roger.
      I may be in the same situation as David in Chicago but I wanted to double-check with you on this: I live in a suburb of Cincinnati (east side) and have 2 boxwoods that were planted in cone shapes 1 1/2 yrs. ago for an ornamental look. They are approximately 3 1/2 feet tall and have been doing well in spite of last winter. However, I would like to trim the sides of them (1-2 in.) for the first time to eliminate some growth that has distorted the cone shape. Can I do that now? Also, do you have any special tips for trimming them to maintain that shape?

      Thanks much!

    22. Anita Says:

      Green mountain boxwood has been recommended for planting in beds in front of our south-facing home. They would be shielded from the north wind, but would get unfiltered south sun, especially in the summer. Would this plant thrive in these conditions in the Kansas City area?

    23. Roger Says:

      Anita,
      Green Mountain Boxwood is hardy in zones 5-8. Kansas City is in zone 5. You should be OK.

      I’m in northern New Jersey, which is zone 6. I happen to use Green Mountain frequently on projects. Although I mostly do residential landscapes, recently we planted 28 Green Mountain Boxwood along a newly constructed school gymnasium. The building faces south and is all brick. I’m confident it will do well.

      If you plant this fall, consider spraying the boxwood with an anti-dessicant.

    24. Roger Says:

      Julia,
      Yes, I would make the same recommendation as for David in Chicago, i.e. if you can, wait until spring to prune.

      As far as any special tips – just be conscious of shape. Try to maintain a wider base, just like the diagram in the article shows. If you don’t trust your eye, use a straight stick of sorts to hold next to the plant and at the angle you’re maintaining. The stick will clearly show how that line should continue to the base and not curve in (like so many misshaped shrubs are). Keep holding it up for reference.

    25. David Says:

      Roger,
      Thanks for the advice! I’ll be waiting until spring to prune.

    26. Anita Says:

      Thanks Roger! I appreciate you for sharing your expertise and recommendation about an anti-dessicant.

    27. Roger Says:

      Josie,
      To know the plants mature size you would need to know the particular specie and variety. There isn’t any more definitive name on the label, e.g. a botanical name?

      Once you know the exact variety, you’ll know how the plant intends to grow & mature. That information guides you on how far apart to space the plants. There are so many varieties of boxwood, and each has its own growth characteristics.

      Planting them in the summer should be fine as long as proper watering is/was done.

      You should know that if you determine the spacing you’ve given them is incorrect, you can move them fairly easily (and safely) in the spring. I would not do it now (fall) as they’ve probably “set” some root in the ground, and that will help them do well through the winter. You could even give them some winter protection by spraying with an “anti-desiccant” or protecting them with a physical barrier like burlap.

    28. Roger Says:

      Josie,
      Common Boxwood (Buxus sempervirens) is hardy to zone 5. You’ll definitely want to protect yours for the winter.

      I would set up a physical barrier for wind/sun protection, and to protect against any salt (or whatever) from the plow guys.

      We use a material & stakes called “silt fence” on jobs to control runoff and erosion. I think something like that would work well for you.

    29. Roger Says:

      John,
      By definition, what you describe you’d like to do to your boxwood is “renovate” them. You do this by “selective pruning” with a hand pruner. In this post I talk a little bit about selective pruning on boxwood.

      This type of renovation should be done over time (e.g. 3 yrs.). With these selective cuts you’ll be thinning the plant to allow more air and light to enter into the body of the plant. This will begin to make the plant push buds internally instead of all the growth occurring on the exterior. And as you’re making cuts to thin the plant you can also shorten some of the branches to begin the process of reducing its size. Hopefully you can see how a process like this takes time.

      What’s nice about a renovating method like this is, the plants don’t look hacked-back. One would argue you could do that, but they’re going to look nasty until new growth disguises the aggressive cut.

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