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 Shear
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.
- when boxwood is used in “natural, informal gardens”.
- 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.
Topiary 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:
- It’s healthier for the plant because light is better distributed to the foliage.
- 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.
It 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.
I 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.
You 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.
July 3, 2010 at 2:51 pm
Good article. I’m actually trimming this weekend. The diagram with the shapes was excellent. I didn’t realize it was wrong to go in at the bottom. I’m trying to do as much as I can on my first house. I bookmarked your site.
July 3, 2010 at 3:04 pm
Hi Jim,
Thanks for your nice comments.
I’m glad that simple diagram helped you out. It’s amazing how many of the most fundamental things in our trade are done incorrectly.
If you’re doing more work “on the outside” of your house, can I suggest you subscribe to my articles via e-mail or RSS. I have no doubt they’ll help you with your landscape renovation. Please feel free to email me if you have any questions you can’t find answers to on the site.
Take care,
Roger
July 5, 2010 at 11:06 am
What about a gas trimmer vs. a electric one
July 5, 2010 at 8:13 pm
Tom,
I think if you compare good quality, professional models of each (gas & electric), you’re not going to see a difference in quality of cut. In terms of productivity, one might argue that the gas trimmers are more productive because you’re not having to worry about the wire and a power source all the time. I have seen crews use gas powered generators with electric shears.
For years now I’ve had a Little Wonder electric shear with one-sided blades. I take good care of it and have a few sets of blades, which I rotate on the machine. So it’s always sharp. Here’s a link to Little Wonder’s website. They have both gas powered and electric models. http://littlewonder.com/lw-trimmers_single_edge.asp
I was thinking to suggest renting each type to help with your decision, but I’d be concerned the electric ones you’d rent would not be of the caliber that I’m referring to.
If you’re in the trade you could ask for opinions from other landscapers. If you do I’d be interested in those opinions. There is a way to do “polling” on a website. I’m going to look into it because there are many topics to poll and see what other people think.
If you ever have the chance, please let me know what you find out and decide on.
Roger
February 28, 2011 at 12:14 pm
I have a nice row of naturally short boxwoods. Last spring I tired to selectively prune by going into the base of the plant and thinning a bit. This seemed to let in more air and light and the result appeared good. During an August drought my husband was inspired to trim overall for length. The growth in September was weak and lighter green. This has lasted through the winter. Please advise me on how to care for them this spring. The lighter tips really look funny. (I’m sure you can guess that my husband and I have different ideas about pruning.)
February 28, 2011 at 9:53 pm
Hi Martha,
Yes, you and your husband’s pruning styles are different, but with regard to boxwood they can complement one another.
Thinning out the boxwood selectively is excellent. This is the pruning that truly supports the health and longevity of the plants. Continue to do this when you feel the plants are getting too dense (for their own good).
Shearing the ends for a neater look is, as you know, typical for boxwood. And frankly, they handle it pretty well. I have seen discolored and stunted growth on boxwood before, and no doubt this incident of yours relates to the shearing and dryness. Without seeing the plant(s) my guess is they’ll be fine, especially if the body of the plant seems healthy.
To help with the cosmetics I would do a “light” shearing in the early spring to clean off some of the discolored/stunted ends. Do this before the new growth starts, but not too early.
I’m confident new growth in spring will push out from the stems, and the plant will look normal again. I don’t know if you normally feed the boxwood, but you could give them a fertilizing in early spring just to give them some additional help. If you’ve been getting the snow and rain that we have in the northeast, the ground is and will be plenty moist in the spring. If so, be careful not to over-water. In fact, if they’re established, you shouldn’t have to water until the ground becomes dry again (probably in the summer). Boxwood do not like being too wet!
Take care,
Roger
November 23, 2011 at 11:57 am
Roger, We live in southern Louisiana and have two very large boxwoods at our front door. I do not know how old they are, but the house was built in ’39. They are healthy but way overgrown, how far back can we trim them and can they be salvaged or do we need to remove them and replant? We would like them at about 3 to 4 foot off the ground, not 5 or 6 for upper growth.
Pam
November 23, 2011 at 4:24 pm
Hi Pam,
It’s difficult to say whether you can ultimately get the boxwood down to 3 or 4 feet. I’d recommend you do this in stages (if you have the time and patience).
Make your initial pruning cuts “selectively” – that is: single, strategic cuts using a hand pruner. Generally, you don’t want to make cuts below where existing leaves stop. Follow the top growth down its stem until you see the foliage “thinning”. Make your cut(s) just above that point.
The strategy would be to make cuts like this universally across the top in order to lower the plant’s height as much as you can this first year. I would at the same time “thin” the growth in this upper portion of the plant to let more light in. By letting more light in you’ll encourage the remaining stems to bud and grow more leaves lower down.
If all goes well you should be able to do a similar process next year and lower the plant a bit more. Realize, of course, that the degree of success with this is a variable.
This other article on the blog pertains to pruning similar to this strategy. Maybe you’ll find it helpful too.