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Blue Sterling's Newsletter

Tuesday, March 28, 2002

T he Cedars: Red, white and true

Whether you visit a friend's garden or go for a ride in the country, you'll be amazed at how many plants are called cedars. Mail order nursery catalogs can confuse you as well. If Cedrus libani is cedar of Lebanon, how is Juniperus virginiana an Eastern red cedar? And why is Thuja plicata Western red cedar ? And what about Chamaecyparis thyoides? In the coming paragraphs you'll learn about the cedars you see in the Eastern United States.

"True" cedars are not native to our country, but you will find great examples of these majestic trees in parks and arboreta in Zones 6 and 7. Taxonomists spend their lives researching and revising plant nomenclature. Despite extensive study, they have not reached consensus on the number of true cedars. Some taxonomists separate the true cedars into four species, while others declare that only Cedrus libani, the cedar of Lebanon, and Cedrus deodara, Himalayan cedar are true cedars. These scientists regard the Atlas cedars, Cedrus atlantica, as a subspecies of C.libani. They also view the rare Cedrus brevifolia as a C.libani subspecies.

These true cedars are easy to recognize. Mature Lebanon cedars are about 60' tall, have a flat topped appearance, stout trunk and an open habit. Their scarce horizontal branches are massive. Barrel shaped cones grow upright and often reach 5 inches long! This tree has stiff evergreen foliage that grows in tight clusters on small woody pegs. The foliage is usually green.

You'll usually encounter the Atlas cedar, or more precisely, Cedrus atlantica, as it's blue foliage cultivar. This cultivar, called Cedrus atlantica 'Glauca' is a stunning specimen. It will remind you of a blue C.libani with a taller crown and more open branching.

The Himalayan cedar is fuller, denser and faster growing than the above. As a result, it is a prettier tree when young and very popular. The needles grow on pegs except at the branch tips. Here they occur singly and droop, as do the branchlets. Cedrus deodara maintain a central leader for many years before eventually becoming flat topped. This leader droops and bends easily in the wind. Himalayan cedar are easy to identify from a distance.

As you'd expect from it's name, Cedrus brevifolia has shorter needles than Cedrus libani. This rare species ( or variety depending on which authority you follow) is not common in American gardens.

Cedrus libani ssp. stenocoma is the perfect cedar for cold climates. This tree is native to cold mountain areas in Turkey but is similar to Lebanon cedar in other respects. It is reliably hardy in Zone 5.

How about the native cedars you see growing in boggy areas along the East coast? From Maine to Florida, and into Louisiana and Mississippi you'll find Chamaecyparis thyoides ,the Atlantic white cedar. Chamaecyparis thyoides is a member of the cypress family so it is not a true cedar in the botanical sense. This versatile plant was overlooked by most gardeners until very recently. Atlantic white cedar is a tough, adaptable conifer that is usually found in gardens as one it's cultivars. One of the most popular white cedar cultivars is 'Heatherbun'. This cultivar has fuzzy juvenile foliage. Most folks who see 'Heatherbun' cannot reconcile this compact plant with the 50'trees they see in swamps and lowlands. Chamaecyparis thyoides has become a popular garden plant and problem solver for soggy garden areas.

Thuja occidentalis is a white cedar that may already be in your garden. Thuja occidentalis is also known as eastern arborvitae. You'll find this conifer in the wild in our northern states. It is usually a narrow, cone shaped evergreen plant. The branches are short, grow horizontally and remain on the tree all the way to the ground. Arborvitae foliage is technically needle foliage, but it sure doesn't look like a needle! The foliage appears as flattened, overlapping scales that form fans. When you prune Thuja occidentalis you will notice the fresh, citrus scent of the needles. Thuja occidentalis 'Smaragd' is better known as Emerald Green Arborvitae and is a popular hedge plant.

You probably recognize the native red cedar, confusingly named Juniperus virginiana. This evergreen is common throughout most of the Eastern United States. But did you know that many of the conifers sold as red cedar in home improvement stores are actually arborvitae? In Canada, the western arborvitae, Thuja plicata is called a red cedar.

This Northwestern native plant is becoming very popular in the East. In our gardens, deer seem to spurn this arborvitae, and find tastier treats to munch. You'll recognize Thuja plicata by examining it's foliage. Thuja plicata leaves are scale like, similar to Thuja occidentalis but glossier. The leaves overlap like shingles. Turn a Thuja plicata leaf over and you'll see distinct white blocks. Western red cedar grows well in wet sites and has produced some colorful and dwarf cultivars that you'll want in your garden.

Yellow cedar? You may know this plant better as Alaskan cedar, but we've seen Chamaecyparis nootkatensis called yellow cedar as well. Despite its' cold weather origins, this tree is well suited to gardens from Maine to Georgia. The Alaskan or yellow cedar grows about 8" annually and forms a well branched pyramid with weeping branch tips. Chamaecyparis nootkatensis is happiest in moist. well drained soil. 'Green Arrow' (below), a narrow weeping cultivar, is a popular specimen choice for small gardens. All yellow cedars shrug off pests and disease. These trees are easily identified by foliage. The scale-like leaves grow in four similar rows and end in spreading tips. Prune a yellow cedar and you'll never forget the pungent aroma of the cut foliage. Fortunately, most cultivars of this attractive tree never need pruning.

Those of us who grew up in suburban homes in the Mid Atlantic states during the 1960's remember Japanese cedars. Almost every home was landscaped with a catalpa tree, a couple of yews and a Japanese cedar. Sound familiar? Well, if you were not too traumatized by what appeared to be a shaggy telephone pole, the Japanese cedars have a lot to offer your garden.

Cryptomeria japonica is the botanical name for Japanese cedar. The trees planted during the sixties were generally seedling grown cedars, planted to meet town landscape codes and keep projects under budget. Another reason builders planted Japanese cedar is that these trees are tough to kill. Deer don't bother with most Cryptomeria japonica cultivars. They thrive in loam, sand, or clay and tolerate salt spray.

Japanese cedars have distinctive reddish brown bark that peels off in long strips. Their foliage is bluish green and is usually awl shaped. The foliage of many Cryptomeria japonica cultivars changes color in cold weather. Some of the most exciting garden plants available today are Japanese cedar cultivars.

We've discussed the most popular cedars you will find in American gardens. The following list summarizes some favorite cedar cultivars for today's garden. Do you have any favorites? Share them with us!

Cedrus atlantica 'Glauca Pendula'. This weeping cultivar will assume whatever shape you wish, so let your imagination run wild! Grows about 8-10" annually. (below left)

Cedrus deodara 'Blue Ball' (above right). This miniature globe is a Blue Sterling introduction. Reaches a rounded 30" in 15 years. Perfect for troughs and container plantings.

Cedrus libani 'Sargentii'. Superb dwarf prostrate or pendulous (depending on staking) cedar. Try it for an unusual groundcover. (below)

Cedrus libani ssp. stenocoma. Full size true cedar hardy in Zone 5.

Chamaecyparis nootkatensis 'Green Arrow'. Squeeze this narrow weeper into a corner of your garden.

Chamaecyparis thyoides 'Little Jamie'. Dwarf, conical native loves wet sites. Perfect alternative to Dwarf Alberta spruce.

Cryptomeria japonica 'Spiralis'. Soft, twisted lime green foliage. Hugs the ground before deciding to grow into a small pyramid.

Thuja occidentalis 'Malonyana Aurea'. Brilliant gold cultivar with a narrow habit.

Thuja plicata 'Grune Kugel'. Slow growing "Green Cushion" from Germany. Dwarf with a mounding habit.