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punctuating the garden: columnar evergreens

SOME PARAGRAPHS NEED PUNCTUATION, and my garden’s like that–in need of the occasional exclamation point, specifically.  So for the first time in 30ish years of gardening, I’ve gone and done it: adopted an evergreen “!” to help me state the case. My choice was a columnar American arborvitae, Thuja occidentalis ‘Degroot’s Spire,’ but there are others (especially if you garden in a slightly warmer zone than my 5B).  That’s it doing improvised temporary duty in a pot, above, while I figure out where it will really go.  More on the topic of vertical accents, in print or podcast:

get the podcast

THE MAY 7, 2012 EDITION of the weekly podcast I do with the nation’s smallest NPR affiliate, Robin Hood Radio in Sharon, Connecticut (WHDD), was on the topic of vertical accents in the garden, particularly evergreen ones. Stream it now, or subscribe free on iTunes or the Stitcher app. Enjoy!

This first-ever columnar conifer in my garden career came about quite by accident. I was actually looking for what a friend refers to as “a blob” (a sort of lumpy, wider-than-tall, hummocky-shaped shrub) to replace a Daphne ‘Carol Mackie’ that was badly snow-damaged last fall.

Shop as I might for the right new “blob,” I saw nothing that was just right. And then I bumped into another friend at the garden center, who said, “Why not something vertical instead? Change it up.” Aha!

punctuation points i considered:

  • Thuja occidentalis ‘Degroot’s Spire:’ A columnar form of American arborvitae with twisted, almost spiraling foliage that gets to 10-20 feet and 3 to 5 wide, depending who you believe and how you prune. Zones 2-7. Sun to part shade.
  • Ilex crenata ‘Sky Pencil’ (Japanese holly):  Grows to 10 feet and 2-3 feet wide; will need help, such as from a cat’s cradle of fishing line, to prevent splaying open when it’s tall. Zones 5-8 or 9, though I worried this wouldn’t be hardy enough for me; some references disagree on the zone.  Full sun best but adapts to part shade.
  • Buxus sempervirens ‘Graham Blandy:’ A columnar boxwood reaching 6 feet or more (maybe 15 after many years) but under 3 feet wide. Zones 5 or 6-8. Full to part sun. Weston Nurseries also has a good profile of this one. I’m also interested in learning more about the newer cultivar ‘ Monrue,’ a.k.a. ‘Green Tower,’ 9 feet tall and under 2 wide.
  • Cephalotaxus harringtoniana ‘Fastigiata:’ This plum yew is much less tight and narrow, especially as it gets older, than the others, at 10 feet tall and 6 feet wide with a vase-shape. It’s also not suited to heavy snowload country (she says, having maimed it herself); Zones 6-9. But if you want something with a linear leaf (yew-like foliage) and can accommodate the width…. Part sun.

SUCH COLUMNAR SUBJECTS would also be useful grouped for hedging, of course. A note when grown in pots as a specimen: If you leave a big weatherproof pot out in winter, the plant’s roots will have less insulation that in the ground (meaning they’ll be less hardy). Select something about two zones hardier than your actual zone for such exposed usage. Or plan to put them in an insulated shed or garage for the winter, which will cheat you a half-zone or a zone, in my experience. Here in Zone 5B I can overwinter a potted Zone 6A or maybe a 6B plant in my garage, but I wouldn’t count on even a 5B plant liking life out in the elements in a pot–a Zone 3 plant will make it, and a Zone 4 one might. Experiment, since each winter weather, plant, pot size and shelter makes for a different combination.

Categoriestrees & shrubs
  1. AC says:

    Such a gorgeous element. This gives me an idea to plant a conifer beside to a tall, vertical rock in the garden for “punctuation.”

  2. PT says:

    Ohhhhh, I love conifers! Weeping white spruce, Picea pendula “glauca”, is my longtime vertical garden accent…very narrow footprint, branches stiffly pendulous, formal. From pot to several transplantings, it’s been very forgiving and earned a permanent spot in my garden! Weeping Serbian spruce Picea omorika “pendula bruns” is a newer favorite for me…a very narrow artistic form, elegantly drooping branches, shimmering tricolor needles, maroon cones.

    Less formal verticals that grow slowly and still don’t hog too much horizontal real estate are Picea orientalis “skylands” of tiered graceful form and showy golden color, and Abies koreana “Horstmann’s silberlocke” with white needles like a flocked Christmas tree year round. All are thriving in my 5A garden for 5 to 15 years.

  3. Vickie Cardaro says:

    My experience with buxus ‘Graham Blandy’ is that the best it ever looks is nearly the first day you plant it. Typically purchased at no higher than 3 1/2-4′, it easily splits under the weight of snow, due to the narrow, many-branched interior. After nearly every first winter, mostly what’s visible is it’s interior architecture – considerable leaf-loss from tiny fractures, in addition to some breakage of main and/or side branches. I stopped using it years ago.

  4. marcia says:

    Love deGroot despite animosity toward many arborvitae. Gave several (in pots) as Christmas gifts one year. Was surprised to see the being sold at a closeout-discount store last month.

  5. angela says:

    What size pot is your Thuja planted in, and do you leave it out all winter? Looks like it might be one of those lightweight pots that can stay out in the cold.

  6. Margaret Andrews says:

    If you put them in a shed or garage overwinter, is it imperative that they have light?
    My garage is well insulated but has no window. As they are dormant during winter do they need light?

  7. Diane says:

    What can you tell me about the famous Italian exclamation point…the Italian cypress trees? I have about 40 of them lining my driveway and local men–who just happened to have the right equipment–suggested they should be moved further away from the driveway (the roots will eventually break the concrete, they warned) and further apart (they are currently about 7 feet apart) for the mere fee of $3000. They have been in the ground for about 4 years and some haven’t grown much while others have tripled in size (the largest is now about 8 feet tall). Most of them are nice and tidy, but some have “wacky” branches that flop to the side and ruin the lines of the vertical. I wonder if they should be pruned or tied to the main trunk? If anyone knows an online resource on Italian cypresses I’d love to know about it. On a smaller scale, it’s very popular here to plant three cypresses in a triangular pattern.

  8. franky says:

    i havent been successful in growing these plants..ive grown 2 so far and none of them has survived! why !! :(

  9. Larkspur says:

    I love the podcast… so soothing to hear gentle plant discussions while commuting. It all gets filed away and sometimes even resurfaces when it’s useful :) The week we got rain (was it late April?) I couldn’t wait to log onto the podcast and hear the relief in your voice.

    1. margaret says:

      Thanks, Larkspur, and nice to see you here saying hello. I am definitely affected by the weather — my whole temperament/tone goes along with whatever’s going on outside, you’re so right.

      Hi, Vicki. My friend who has used it for years definitely keeps it trimmed and also grows it in a sunny spot. Of course box will do OK in some shade, but it gets looser (and more inclined to splay, as when not trimmed regularly to keep it tight). With the ‘Sky Pencil’ Japanese holly he uses fishing line to keep it upright — that one is really apt to open. Thanks for the feedback.

      Hi, PT. What a great list! So nice of you to come enter it all here to tempt me next time I go plant-shopping. :)

      Hope to see you all soon again here.

  10. Diane – Sounds to me like those guys were looking for work. Frankly, I have never heard of Junipers breaking the concrete. Are they right on the edge, ie. touching the concrete? Here in NC we use De Groot spires to get the effect though they are never quite the same as Italian cypress which get much taller and wider (depending on the source). For errand branches, if they are young, I would try tying them in first to the main trunk or other vertical branches. If they are old and stiff, try pruning – a little at a time to make sure you don’t leave a hole.

  11. Deborah Banks says:

    My favorite vertical so far is Juniperus communis ‘Gold Cone’. I mean, favorite that I grow — wouldn’t we all love to be able to grow Italian cypress! It is hardy for me and stays tightly narrow. I also like Berberis ‘Helmond pillar’ — it takes on more of a vertical fan shape (broader at the top than the bottom) but still adds a graceful vertical look.

  12. DFP says:

    This piece is perfect timing for me. I’ve been yearning for vertical punctuation points after a trip back to England, where many of my sisters grow fastigiate Irish yews. I would love to too, but see they’re not hardy in my zone 5a garden. So thank you for all these other suggestions. I have much to ponder.

  13. Alejandro says:

    I just finished planting most of the “anchor” plants for my new long border and right at the end, as an exclamation mark, I planted a golden arborvitae. A yucca will serve as the dot. I got it at the Berkshire Botanical Garden plant sale and that’s why I missed seeing your garden this past Saturday, I’m glad to see there’ll be more opportunities later this year.

  14. Jess Hilton says:

    Love your photo and website!I just love all conifers in my garden .They really are my backbones and I use them extensively here in NC which is z7b.Chamaecyparis,junipers and thujas do wonderful here.It is nice to have them in my garden because even in the middle of the winter when everything else is dormant they are in their glory!

  15. I have been out shrubbery shopping today looking for just the right plant to give some separation between our driveway and the neighboring house. I think a few of these might do the trick. It looks lovely in your beautiful garden.

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