Someone posed a question to me about choosing an arborvitae for a hedge. But he had very specific criteria in mind regarding growth (and growth rate) and drought-tolerance:
"I need to put a hedge on one side of the property line," said he. "My problem is that I wanted to do a type of arborvitae, but I have not really found one that meets these requirements:
- It is low maintenance (I especially do not want to have to water it much)
- It does not get bigger than 4 feet in width
- It has a relatively fast growth rate.
"Can you suggest a type of arborvitae that would work in my hedge?"
'North Pole' Arborvitae a Promising Choice
I have recently done a test planting with a type called 'North Pole' arborvitae, and I have been very pleased with the results so far. This shrub has displayed unexpectedly good drought-tolerance for me here in New England (USA). You will have to water it to get it established, but, after that, if you do not water it very much, not only may it survive, but depriving it of irrigation in this way may actually restrict its size to the dimensions you desire. I cannot, however, praise its growth rate as being anything out of the ordinary.
Speaking more generally (that is, excluding 'North Pole,' since my trial will need a few more years before I can issue a definite recommendation), if you are committed to some type of arborvitae, I am not sure that any ideal solution exists; only compromise solutions would be available.
While American arborvitae (that is, northern white-cedar, known botanically as Thuja occidentalis) is not the least drought-tolerant of shrubs, nor is it among the most drought-tolerant shrubs. At best, I would characterize its water needs as average.
Furthermore, the amount of water an arborvitae shrub receives directly impacts one of your other criteria: growth rate.
Generally, arborvitae is not an exceptionally fast-growing shrub, and insufficient watering slows them down even more. 'Green Giant' is an exception in terms of growth rate (it is a fast-growing arborvitae), but it is way too big for the size criterion that you have provided. You run into the same dilemma with the 'Hetz Wintergreen' cultivar: it is fast-growing, but its projected dimensions at maturity suggest that it will become too large for your tastes.
One compromise route to take would be to buy an established 'Emerald Green' arborvitae (a Thuja occidentalis cultivar, like 'North Pole'; its alternate cultivar name is 'Smaragd'), thus reducing the importance of the growth-rate criterion. Furthermore, to do everything possible to minimize watering needs, you would have to prepare an ideal soil for it (working in organic matter to promote water retention) and mulch properly to further retain water. With a size at maturity of 12-14 feet in height and 3-4 feet wide, it is more in keeping with your size criterion than is 'Green Giant.'
If drought-tolerance is of the highest priority for you, you may wish to consider eastern red-cedar, which is a kind of juniper (not a type of arborvitae).
Neither northern white-cedar nor eastern red-cedar nor western red-cedar (see below) is a true cedar.
Other Types of Arborvitae
Michael Dirr (Dirr's Encyclopedia of Trees & Shrubs, pp.801-805) discusses two other species of Thuja:
- Oriental arborvitae (T. orientalis; alternate name, Platycladus orientalis)
- Giant arborvitae, or "western red-cedar" (T. plicata)
Dirr remarks on the "vertically arranged sprays of foliage" on Oriental arborvitae, a tree of Korea and northern China. At maturity, it is 18-25 feet high and 10-15 feet wide. Grow it in planting zones 5-11.
Whereas T. occidentalis is native to eastern North America, T. plicata (zones 5-7) calls the Pacific Northwest its birthplace. Dirr gives its dimensions in the landscape as 50-75 feet high and 15-25 feet wide (thus justifying the common name of "giant arborvitae") but notes that cultivars more suitable for one's yard do exist, such as 'Zebrina' (30 feet in height).
He observes that 'Green Giant' (mentioned above) is thought to be a hybrid of T. plicata and another species, T. standishii. According to ArborDay.org, it stands 50–60 feet tall at maturity, with a spread of 12–20 feet. They add that its growth rate can be as fast as 3 feet per year.
Not all types of arborvitae are tall and narrow in shape and a plain old green in color. T. occidentalis 'Golden Globe' bucks the trend on both counts, having a round shape and displaying foliage of a light golden color. It grows to be 3 feet high by 3 feet wide and is suitable for USDA zones 3-7. There is even a weeping kind ('Pendula,' 15 feet tall, cold-hardy to zone 3) of T. occidentalis, but I do not recommend it highly since it requires staking.
Other golden kinds include:
- T. occidentalis 'Filip's Magic Moment': According to Missouri Botanical Garden, it is "a naturally-occurring branch mutation of Thuja occidentalis ‘Smaragd'" and has "golden yellow-green foliage" (maximum height 8 feet, maximum width 3 feet, zones 3-7). As a young plant -- before it begins to sprout -- it looks like a globe arborvitae.
- T. orientalis 'Aurea Nana' (also called "Berckman's golden arborvitae"): Less cold-hardy than are many types of arborvitae (zones 6-9). When you see the Latin, 'Nana' in a cultivar name, that indicates dwarf status, and, indeed, this shrub matures to about 6 feet in height, with a width slightly less than that. 'Aurea' is also Latin and lets you know the plant has golden leaves.
- T. occidentalis 'Rheingold': 5 feet high, with a spread slightly less than that (zones 2-7). One of the better types of arborvitae if what you are seeking most is rich golden foliage.
Drought-Tolerant and Fast-Growing? Not So Much
Let me elaborate on the points about general drought-tolerance and growth rate (discussed above) by citing from a couple of resources:
At the Arbor Day site, among the conditions listed to maximize growth rate for arborvitae shrubs, we find, "Soil that is moist, rich and deep, but well-drained; loam or sandy loam." And among potential problems, we find, "In times of drought, tree watering is important."
Meanwhile, on the Ohio State University site, arborvitae is said to have, in general, a "slow growth rate" and to prefer "a moist, well-drained, loamy soil in full sun."
What Beginners Should Extrapolate From This Q&A
While the nature of this reader's question is specific to choosing a type of arborvitae to grow in a hedge, the question follows a familiar pattern that goes something like this:
- I need a plant that will function as X in my landscaping
- The plant's dimensions must be such-and-such
- I do want the plant to have Y characteristic
- I do not want the plant to have Z characteristic
Of course, in addition to such considerations, one must always properly marry a plant's sun or shade requirements to the spot where one is contemplating installing it.
Sometimes, if you conduct your plant-selection research very thoroughly, you will get lucky and find a plant that meets all of your criteria and will be perfect for the location you have chosen for it. You have every right to feel ecstatic when that happens because it is truly one of the greatest feelings you can experience when landscaping.
Very often, however, you will not be able to achieve this ideal. There will be one sticking point that throws a monkey wrench into your plans. What is the solution? In a word, compromise. Something has to give. You may have to:
- Settle for a type of plant that isn't 100% in-line with your aesthetic ideals
- Take on more landscape maintenance chores than you were hoping for
- Pay extra money for a mature specimen (as in the example above)
Remember, "compromise" is not always a dirty word. It is also important to keep in mind that a landscape is more than the sum of its parts. You may not gain total victory in every individual battle, but what matters is that you win the war: that is, achieve an overall landscape design that is both highly functional and also pleasing to the eye.
Can I help you research a particular plant? If so, just browse through my List of Plants in Alphabetical Order.