Some plants are not shown the appreciation they deserve. They don’t demand it with flashy flowers or foliage so instead, they are relegated to the backgrounds of our landscapes – workhorses working (or growing). Arborvitaes are a prime example.
Some are planted as hedges; others provide privacy. Some create wind blocks; others play a part in foundation plantings. Many are lucky enough to stand out in winter when other plants have been reduced to bare branches – some as grand specimens; others as accents in perennial gardens or shrub borders.
Arborvitaes are easy-to-grow, low-maintenance plants. Plant them in full sun to light shade in average, well-drained soil and protect them from harsh winter winds. Amend clay soils with compost when planting. Water arborvitaes regularly during their first season in the garden while their roots are establishing.
One thing arborvitaes cannot survive is prolonged drought. Spread a 3- to 4-inch layer of mulch over their root zones to help the soil retain moisture and water them during extended dry periods.
Arborvitaes do not require pruning but can be sheared into hedges or pruned to control their size. Most tolerate heavy pruning, but old plants growing in shady conditions develop dead zones that are not able to produce new growth. Prune arborvitaes in early spring before new growth begins.
In fall, foliage in the center of arborvitaes may turn brown and drop, prompting anxiety and calls to garden centers and Extension help desks. This is part of the natural aging process, like leaves falling from maples and other deciduous trees, and is rarely a cause for concern.
Thuja occidentalis, commonly called American arborvitae, is native to eastern North America. Tall, pyramidal trees grow 40 feet tall or more, but there are many cultivars sized for our landscapes. Emerald Green (also sold as Smaragd) is often chosen for suburban landscapes. It grows up to 15 feet tall and 5 feet wide. It retains its emerald green color throughout the winter.
I prefer Techny. It is similar in height to Emerald Green, but grows faster and displays a looser, more natural appearance. Technito is a small chip off the Techny block. It tops out at 6 feet tall and 3 feet wide. Use Technito in large urns flanking a grand entrance or as an accent in a shrub border. Both of these stand up to heavy snow without splitting.
American arborvitaes are also available in rounded forms. Woodwardii grows 5 to 8 feet tall and wide. Golden Globe is also globe-shaped but smaller – 4 feet tall by 4 feet wide – and, as its name implies, offers golden yellow foliage. Hertz Midget is even smaller with dark green foliage. One of my favorites, Mr. Bowling Ball, is perfectly named. Its lacy, blue-green foliage grows in a dense, perfectly-round, 2- to 3-foot globe.
Thuja plicata, commonly called western red cedar, is native to the Pacific Northwest, extremely long lived and quickly grows up to 200 feet tall in its natural habitat. They are more shade tolerant than American arborvitaes.
I planted three of the cultivar named Green Giant in a shrub border about ten years ago. They were tiny – just a foot tall – when I planted them, and they are almost 25 feet tall today. I watered them consistently their first year and then they were on their own. With a bit more TLC, they can grow as much as 3 to 4 feet per year until they top out at around 40 feet tall. Either way, they quickly screen unwanted views or form a windbreak. I love their loose, natural branching form so much, I just planted 3 more at the back of our property.
Whipcord is a unique variety of Thuja plicata. Cord-like, shiny green foliage rises from the center of the shrub and arches out like water from a fountain. It grows slowly to a mature size of 4 to 5 tall and wide. The foliage is tinted bronze in the winter. Thuja plicata ‘Whipcord’ is also found grafted on a standard, resembling a tree right out of the pages of a Dr. Seuss book.
Plan to add an arborvitae or two (or three) to your landscape this year. Below is a chart of several different varieties to help you choose the perfect one. Garden with me!