Columnar trees work well in smaller garden spaces

This time of year, I always try to touch on the topic of tree planting. So, I apologize in advance if I start to sound like a broken record. Fall is — hands down — the best time to plant trees in our area. Dormancy, cooler temperatures, and less fuss are all factors that contribute to this favored window of tree planting.

Perhaps the most important thing to consider when choosing trees for your garden, is the mature size of the plant. Planting the right tree in the right place should always be on your radar, to avoid any future problems. Many of today’s urban gardens are small, though, with close proximity to neighboring houses, streets and utilities. But even with limited planting areas and awkward spaces, you can rest assured that there’s still a great selection of trees from which to choose.

Many deciduous and evergreen trees have a columnar or fastigiate form, meaning that they grow tall and narrow, keeping the shape as they mature. This upright habit (similar to a structural column) is perfect for certain landscape limitations.

The terms columnar and fastigiate are often used interchangeably, although they are slightly different. Columnar trees typically have one main stem or trunk, where fastigiate trees usually have multiple stems. Both are treated as practically the same in the nursery trade, though, where production of these trees has ramped-up over the last few years.

“Columnar trees are perfect for smaller, tighter garden spaces, and we have seen an increase in requests for them over the past few years,” said Jane McCleary, Sales Manager at Piedmont Carolina Nursery. Piedmont Carolina is a commercial, wholesale only nursery in Colfax.

Whether we’ve planted or considered them for our own gardens, we’ve all seen these upright growing trees in various landscapes. A commonly planted columnar evergreen is ‘Emerald Green’ Arborvitae, which is often used as focal point in a landscape bed or to create a tall hedge.

I’m sure there are many plant professionals who would argue that ‘Emerald Green’ is more a shrub than a tree, considering its growth rate and habit. I absolutely view it as a mid-sized tree, though, seeing as it grows to 15 feet tall. I suppose other upright evergreens and conifers could be referred to as both shrubs and trees. But for the sake of this conversation, I’ll refer to all these columnar evergreen and deciduous plants as trees.

Another great columnar conifer is ‘Degroot’s Spire’ Arborvitae. It has a wonderful tight habit and is an extremely narrow, vertical grower. This specimen will grow up to 20 feet tall, and only 4-5 feet wide. It seems that the nursery industry can’t grow enough of these trees to keep up with the demand, as every garden center sells out quickly.

Columnar deciduous trees are in high demand, too, which is evident from the inventory of commercial nurseries and retail garden centers. Common trees like sweet gum, oaks and maples all have fastigiate cousins now, which are becoming widely available.

“Columnar trees like Carpinus ‘Fastigiata’ and ‘Frans Fontaine,’ Quercus ‘Beacon’ and ‘Green Pillar,’ and Liquidambar ‘Slender Silhouette’ are in high demand,” McCleary said. “We have increased production on these trees as much as possible, and we are always trying to add new varieties to our product mix.”

Some of these new varieties McCleary mentioned include ‘Gold Spire’ Ginkgo and ‘Persian Spire’ Parrotia. These two specimens not only tout upright habits, but they have other great qualities, too. ‘Gold Spire’ grows up to 18 feet tall, 5 to 6 feet wide, and it has an intense yellow autumn color.

‘Persian Spire’ has beautiful foliage from spring through fall. Its leaves emerge purple in spring and fade to a bright green with a purple margin. The foliage turns brilliant shades of red and yellow in the fall.

There are many reasons for planting columnar trees in our gardens and landscapes. As I mentioned before, small or tight spaces might demand that tall, narrow species be planted. But these trees can make a bold statement even in wide open spaces.

A columnar tree can accentuate a planting bed, drawing the eye upward. A fastigiate tree can make an area pop, creating a bold botanical expression along the site line of a garden. I’ve heard columnar trees described as exclamation points in the garden, as they boldly emphasis height and contrast.

Planted together in rows, columnar trees can create a graceful formal hedge or screen. ‘Emerald Green’ Arborvitae are often planted as such, as are columnar oaks like ‘Crimson Spire.’ Just make sure to space your plants according to their mature width, keeping in mind if you want a dense or spacious screen.

Other choices include ‘Regal Prince’ Oak and ‘Tsukasa Silhouette’ Japanese Maple. These are two upright deciduous trees planted outside Bobby Boy Bakeshop in Winston-Salem. Next time you’re by there, take note of how their graceful habit both accentuates the building and respects the limitations of the parking lot and nearby street.

The City of Winston-Salem has done a great job of planting columnar and fastigiate trees in certain areas. Some varieties they regularly use include European hornbeam, Armstrong maple, and Musashino zelkova.

“We typically plant fastigiate, columnar trees in the downtown areas where there is little room for the canopy to spread laterally due to physical obstructions such as buildings, traffic signals, sidewalks or lanes of travel,” said Derek Renegar, Urban Forester for the City of Winston-Salem.

“Selecting an upright growing species drastically reduces the amount of maintenance and pruning required to accommodate the infrastructure,” Renegar said. “This also means healthier trees when they are not subjected to drastic pruning to avoid the many obstacles associated with a downtown urban setting.”

So whether it’s because of space limitations, aesthetics or impact, there are many design principles behind planting columnar trees. Even utilizing an upright tree in a large container can make a dramatic statement in your outdoor areas. I encourage you to visualize what these tall, narrow trees can do for your garden.

Amy Dixon is an assistant horticulturist at Reynolda Gardens of Wake Forest University. Gardening questions or story ideas can be sent to her at www.facebook.com/WSJAmyDixon or news@wsjournal.com, with “gardening” in the subject line. Or write to Amy Dixon in care of Features, Winston-Salem Journal, 418 N. Marshall St., Winston-Salem, NC 27101.

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