THERE IS ONE punctuation mark I shy away from in writing that I should, however, use more in the garden. That’s the exclamation point–which translates botanically as columnar trees and shrubs. My longtime friend Ken Druse, author of many books including “The New Shade Garden” and “Making More Plants,” got me thinking about vertical accents, and the essential role they play in creating emphasis in the landscape. (Those are columnar ‘Newton Sentry’ sugar maples in his New Jersey garden in fall, above.)
Like a carefully crafted sentence, the garden needs proper punctuation to read well, and clearly convey what’s going on. On the November 28, 2016 edition of my public-radio show and podcast, Ken and I discussed design challenges that these tall and narrow things answer; the technical difference between the columnar and fastigiate plants; and some of his favorites.
Read along as you listen using the player below (or at this link). And then scroll all the way to the bottom of the page to enter to win a copy of Ken’s “The New Shade Garden,” loaded with more design inspiration and great plant choices to consider.
columnar tree and shrub q&a with ken druse
Q. You got me thinking on our phone call the other morning–we were talking about earthworms and all these other crazy things…
Q. …and then you started talking about columnar plants, and it really got me thinking. I suppose the classic image when you say “columnar tree” is the so-called Italian cypress. We’ve all seen them in travel posters for a Mediterranean holiday–and paintings by Vincent Van Gogh. [Below, a view of the gravel garden at Ken’s, with some vertical accents.]
A. Exactly, and if you live in a Mediterranean climate you can grow a Cupressus sempervirens, a nice Italian cypress. You see it in paintings, as you said, and it makes everything look and feel important–monumental in a way. But we can’t all grow those, because we live in colder climates or even in hotter climates.
I always think about what can I grow that’s like an Italian cypress–and the answer is nothing. But there are several things, many of them junipers, that are very narrow and tall, if not as tall as an Italian cypress.
Q. Are poplars another thing like that–I have seen them used to line a driveway, for instance, but it doesn’t look like it always works out too well.
A. No, and you still see those online: “Grow a fast security hedge overnight!” And they’re really inexpensive–those Lombardy poplars [Populus nigra ‘Italica’], which are the ones you see in European paintings. I think it gets too hot in most of North America, but there are some disease-resistant varieties that are around now.
So you’re talking about things we can’t grow; that’s great. [Laughter.]
Q. Great; we got that figured out; now here’s what we can’t do.
Before we go into particular plants for different uses, maybe we should first define a couple of words. When we’re talking about very vertical woody plants, two words show up when you’re reading about them, and also sometimes in the plant names and descriptions: columnar and fastigiate. You and I both, after our conversation the other day, we got fascinated with the fact that neither of us knew exactly what the difference was.
A. When you look online, or in a nursery catalog, you find those words: columnar, and fastigiate. Often those words are in the names of the plants–like it will be columnaris, or fastigiata. [Above, a fastigiate red peach tree.]
I found one definition that was one way, and the next one contradicted it. I think that fastigiate is really a technical horticultural term for a woody plant, a tree or shrub–though it could also be herbaceous, but usually it’s with woody plants–when they have ascending branches, branches that tend to grow vertically, grow up.
I usually think of a fastigiate plant as being kind of egg-shaped, but I think more specifically, it’s that it has ascending vertical branches.
When I see columnar, I think it’s like a column–cylindrical. Sometimes you see pictures of trees online that look like green telephone poles, they’re so narrow. But I think columnar is more of a descriptive term, not really a technical term.
Q. So fastigiate things are columnar…
A. ..can be columnar… [Laughter.]
Q. …but all the columnar things are not necessarily fastigiate. I started going out into the garden and looking at the couple of conifers that are fastigiate, and it seems that as you said it’s that the branches are almost vertically parallel to the trunk, whereas with a columnar thing, they could even be weeping branches–but they’re held tightly in a downward action next to the trunk so they make a column. The branch direction isn’t so specific in columnar as it is in fastigiate.
A. I think a columnar tree could be fastigiate.
Q. Correct–I agree. But I’m saying it could also be weeping branches, or short little spiky branches; it doesn’t have to be vertical. Fastigiate has to be vertical, I think.
A. Or close to vertical, yes, growing sort of parallel to the trunk.
Q. Let’s talk about some of the reasons practically and aesthetically you might seek a punctuation point in the garden. I know you have certainly made room for them in your garden, but in general what do we use these for, whether columnar or fastigiate [laughter]?
A. A columnar or fastigiate tree or shrub could be a specimen, as a kind of focal point, perhaps at the end of a vista or a border–just like you said, an exclamation point. So you’ve got your beautiful border and then, “Pow!” at the end of it. These days people use exclamation points all the time, when they are texting.
Q. If we were designing our gardens the way we are “talking” online, whether in text or on Facebook or whatever, the whole garden would be exclamation points. [Laughter.] It would all be columnar.
A. Maybe it’s because we can’t make letters bold in a text or italicize them, so you’ve got to make that point in case you weren’t listening. [Laughter.]
I’ve also seen vertical plants used along a border, so they carry your eye and make movement. If you see a shrub or tree that’s round, or globular, you sort of stop. If you see alliums standing in a garden–those balls–you stop and look. If you have these straight lines going up and down, your eye just carries along. So that’s one way you use them in a border or bed.
Q. They can also be in tight spaces, obviously, so if that border or bed is right next to say your driveway, you an still have room for a backdrop of considerable height, like a tree, yet not overhang the driveway or boundary of your property–whatever it is.
A. If you have them between the sidewalk and the street, you might not have room for a big tree, and you might not want a parked car to run into the branches. If you’re in an urban garden, you don’t have space for a big tree, but you still want to have a tree. And if you have a very vertical one it won’t cast a lot of shade, and of course it fits in a tighter space.
Q. I love them in containers, because I can move them around and put them where I need a particular specimen or statement, like you said, in a spot. I can wheel them around on a handcart.
A. And if you have twins [laughter]–which a lot of people do, when they have two vertical trees or shrubs, maybe evergreen or deciduous, in pots–and you put them at the entrance to your path, or on either side of your door. It makes a very wonderful formal statement. I love them in pots if they’re hardy enough, because you can just move them around.
Q. So we have specimens; we have the announcement at the end of an axial view of “You have arrived!” as a statement for emphasis. We can use them near a road where there no room, or create a living screen or fence–though they’re not literally as narrow as a fence, but they’re pretty narrow. And we can use them in containers, among other strategic uses.
In your own garden, what are some example of what happened there and why you got into columnar trees? [Above, ‘Slender Silhouette’ and other smaller vertical accents at Ken’s garden.]
A. You mentioned using them as a screen. Sometimes they’re promoted as “no-trim privacy screens” because they don’t pruning, but you might get a faster effect with shrubs that you do have to prune. One of the first trees that I planted here: I bought seven ‘Newton Sentry’ maples [Acer saccharum ‘Newton Sentry’], which are very narrow-growing. They were found in the Newton Cemetery in Massachusetts around 1890 and propagated.
They’re very hard to find these days, but they are vertical, and I planted them 7 feet apart. I thought that they would grow together to make kind of an elevated hedge, an elevated screen. They’re about 20 feet tall now, but they’re barely 3 feet wide. They’re fantastic–but it wasn’t exactly what I expected, but I think it’s one of the most striking things in the garden.
Q. Now you said “found”–that they were found in a cemetery. That brings up a good point. Found as in a lot of these things may be the same genus and even species of a tree that we know, like a Gingko, but they are a different form, and sometimes they were just discovered, like there was this aberrant individual plant. Is that what happens?
A. Right. I guess in the case of annuals and perennials people might breed for this, because you can get a result in about three years. But in the case of trees, shrubs, evergreens–they’re usually discovered. Maybe someone sows 1,000 seeds, and one of the seedlings is very narrow, and there you have one way of finding one.
Sometimes there are mutations that appear on woody plants, mutated cells that grow in a different way. Sometimes we call those witches’ brooms or sports, and they propagate the pieces of that particular aberrant growth. You know we have all those tiny little dwarf evergreens, and most of them came from witches’ brooms.
And sometimes in the case of the ones at Newton Cemetery, they just appeared. A nurseryman found them and thought, “Hey, this is interesting.” There are actually two that came out of Newton Cemetery. One we would say is fastigiate although columnar [laughter], and the other one just has those tiny side spur branches, and they are the most narrow trees available.
Q. So you have this group of seven of this columnar maple. Some others that you are using strategically?
A. You said strategically, and I have this fastigiate tulip tree that makes people think I thought about this. [Laughter.] Because I am a collector.
Q. You come home and you think, “Now where are I going to put this thing?”
A. Well, sometimes. [Laughter.] But I am attracted to these funny growths, either something that would be tall and is lying down, or something that is lying down and would be tall. I got a Liriodendron many years ago, a fastigiate tulip tree, and it is kind of egg-shaped. It has a very straight trunk. I’ve got two of the maples–the ‘Newton Sentry’ and I also have ‘Monumentale,’ which used to be called ‘Temple’s Upright.’ I just have 2-foot-tall ones, because I want to compare them to the other ones. I think the narrowest of all, and it’s a fast-growing tree, too, is Liquidambar ‘Slender Silhouette’ [below, in Ken’s garden]. Have you ever seen that?
Q. Only in pictures, not in person.
A. They’re so widely available. It was found by Don Shadow, and I think he was in a boat and saw it on the bank. He took some cuttings, and propagated it. When he went back to take some more it was gone–it had been cut down.
Q. Don Shadow is an esteemed wholesale nurseryman, especially of the tree and shrub world–the tree world.
A. These things that we have been talking about–these parts of other plants–are either rooted as cuttings or more often grafted to a seedling of the parent plant or the original plant, because as you said they are almost always species; they’re varieties of different species. So they graft them to the normal species, and the top grows into whatever you want.
‘Slender Silhouette’ [a sweetgum, or Liquidambar styraciflua] is in so many nurseries, and if you’re interested in having a vertical tree, and one that’s fast-growing, that’s a great one. And if you have a little more sun than I have, you get some great fall color, too.
Q. And a tulip tree [such as you mentioned earlier] would have lavish flowers, too, no?
A. Mine has never flowered, and maybe that’s something about some of these. With the sweetgum, people don’t like those kind of spiny balls that are a mess, but the ‘Slender Silhouette’ I think rarely produces the fruits. My Liriodendron has never flowered, and I’d say it’s more than 30 feet tall.
Q. Interesting. When you have these seven ‘Newton Sentry’ maples–remind me, are they in a straight row?
A. They are in a curve.
Q. So not that example, but elsewhere that you have multiples of something columnar–I sometimes like it when they are not all the same age. Meaning, when there is a group of three that calls my eye up a hill or somewhere, and they’re vertical but they’re not equal, not exactly the same size.
A. In the Steinhardt garden [the garden of Michael Steinhardt in Mount Kisco, NY], he has ‘Slender Silhouette’ trees, and it looks like a cathedral [above], because the spires are different heights, and they ascend to the tallest one. My ‘Newton Sentry’ were all the same when I go them, but they didn’t all grow the same. I’ve never pruned them and I am not going to, but for an elevated screen or hedge, it would have been nice if they were all the same height–but they’re not, and I don’t know why. [Laughter.]
Q. The only columnar or fastigiate things I have, I realized after our conversation the other day when I went marching around the yard, are things in pots primarily as I said. There is a Thuja occidentalis called ‘DeGroot’s Spire’ [below, when young], which is fastigiate and a great plant. I have it in a very large terra cotta container, and I am in Zone 5B, and I’ve had it in the container for six or seven or eight years; it gets bigger but not much bigger.
I roll it into the barn in the winter so the pot doesn’t break and the plant doesn’t get windburn. I wheel it out and it’s a great statement piece every year. I have some Taxus, some yews, as well, that are vertical but I don’t recall the names of them.
And I tried a columnar conifer that was shrubby, and in my snowy Northern location, it didn’t work so well. This is one of the other things strategically about using these plants. I tried a fastigiate Cephalotaxus harringtoniana, a plum yew, but it splayed open every time it snowed. So that’s one thing for people with heavy snowloads, and columnar plants with long vertical branches parallel to the main trunk–do you know what I mean–if they’re too soft? The ‘DeGroot’s Spire’ is stiffer.
A. Generally these vertical trees and shrubs want sun. You have to think about it if you’re putting it in an urban garden; you want to have sun on all sides so they stay symmetrical. But I don’t have a lot of sun so that splaying sometimes happens, especially with shrubs.
I have many, many ‘Graham Blandy’ boxwoods [above, and then below in a border at New York Botanical Garden], and I just take some hemp string or green or black yarn, and I tie it to the bottom and spiral it up. The tallest one is about 7 feet tall, but most are about 4 feet tall. I just do a very loose spiral and I used to use a cotton spring, which was great–by the time spring came, it had disintegrated. That’s one way I deal with that splaying, which doesn’t always happen but it can.
Q. With your ‘Graham Blandy’ boxwood, which is a great plant, you have a little invisible help staying tight and together. That’s a good tip.
A. There are several of those fastigiate boxwoods: There is ‘Fastigiata,’ and one that people talk about all the time is ‘Dee Runk.’ ‘Graham Blandy’ is the skinniest. I’ve heard people complain that there are diseases they might get; they haven’t for me.
There is a holly called ‘Sky Pencil,’ and I can’t grow that here, because it is too cold–but the ‘Graham Blandy’ boxwood looks almost identical to Ilex crenata ‘Sky Pencil.’
Q. Any columnar other plants you want to point out? I even read about a red-leaf Japanese maple from Twombly Nursery [Twombly’s Red Sentinel’] that’s columnar; I’ve never seen it in person. I mentioned before that there are ginkgos.
A. There is the ‘Princeton Sentry’ ginkgo, and ‘Gold Spire.’ I was in the Denver Botanic Garden, and in a very shady spot there were these columnar aspen trees. They had beautiful gray and black markings on the trunks, and they were very columnar. I did some research and they were Populus tremula ‘Erecta,’ and they’re Swedish, and they’re hardy to Zone 2.
You’ve probably seen Carpinus betula ‘Fastigiata,’ which is the columnar hornbeam. There are several of those at Wave Hill. Many years ago, like 35 years ago, Marco Stufano planted one of these and as it grew and got older, it’s no longer narrow. But if you look at it inside, there are still the ascending branches, but it’s just that a lot of trees get to a certain height and they don’t get taller, they go wider.
Marco also has that gold variegated plum yew like yours in a container [above]–you’ve probably seen it outside his door.
Q. Maybe I’ll try your trick with the twine. It’s a good idea–and the deer don’t like that plant.
A. And they don’t like the boxwoods, either.
There are lots of columnar oaks–most English oaks tend to be narrow anyway. But there is ‘Fastigiata,’ and ‘Regal Prince.’ Just put “fastigiate” or columnar” into a search engine, and you’ll come up with many examples.
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the November 28, 2016 show right here, and also use the buttons below to subscribe to future shows, free.
(Photographs except ‘DeGroot’s Spire’ from Ken Druse; used with permission. Disclosure: Purchases from Amazon affiliate links yield a small commission.)
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