Which of these photos shows a cedar?
Surprise—all of them do! 1. Is a Western Red Cedar, 2. is a Lebanon Cedar (ailing, I should add—the needles are supposed to be green, not brown!), and 3. is a Mountain Cedar, aka Post Cedar, the ubiquitous plant of central Texas and north-central Mexico.
In fact, the word “cedar” has been applied to around 30 different species of plants in 18 genera placed in seven different families. And those are just the well-known common names! When I volunteered at the master gardener help desk, we often received phone calls about ailing “cedars.” Not being able to see the plant in question, we had to ask a lot of questions just to determine what the caller was talking about:
- “Is it a shrub, or a tree? How big?”
- “Does it have broad leaves, scales, or needles?”
- “If it has scales, are the branches flattened or 3-D?”
- “Does it have cones? What do they look like?”
Most often, the caller actually had a plant in the genus Juniperus. Junipers are frequently called cedars—Bermuda cedar (J. bermudiana), Mountain cedar (J. ashei), and Eastern Red Cedar (J. virginiana) are just a few examples. To make things even more complicated, the Western Red Cedar and the Eastern White Cedar are in the genus Thuja, along with the Northern Whitecedar—which is also known as the Eastern Arborvitae. No wonder people are confused!
So just what is a cedar really?
Most botanists accept four species in the genus Cedrus, the true cedars. They include the Deodar cedar, Atlas cedar, Cyprus cedar, and Lebanon cedar of Biblical fame. All have dense clusters of evergreen needles, although some needles may be spread out along a twig. Large cones stick up above the branches; they tend to fall apart at maturity. All true cedars prefer full sun and loamy, moist, acidic soil with good drainage, and they’re somewhat drought tolerant when established.
Deodar cedars, C. deodar, have 1- to 2-inch needles. They hail from the Himalayas, where they are beautiful, tall trees, growing to 200 feet in height. (Under cultivation, they typically reach 40 to 50 feet in the first 25 years.) Even though they are native to the mountains, they’re only hardy to USDA zones 7, so they won’t grow in Colorado. They are, however, sold for landscape use in warmer parts of the country where they can be somewhat invasive under ideal conditions.
Atlas cedars, C. atlantica, have 1-inch needles. They are native to the Atlas Mountains of northwest Africa. These can be large trees, sometimes reaching over 100 feet in height, with huge sweeping branches. Some individuals have a distinctly blue color (similar to a Blue Spruce), which makes them a striking specimen tree for large areas; in fact, there’s one growing on the White House lawn, where it has plenty of room to spread out. Atlas cedars are slightly hardier than Deodar cedars, surviving winters to zone 6. That’s not hardy enough for most of Colorado. Some botanists consider this a subspecies of the Lebanon cedar.
The Lebanon cedar and the Cyprus cedar are very closely related—the Cyprus cedar may be a subspecies—as you might expect from their adjacent ranges. Both these cedars have very short needles, from ¼ to 1 inch in length. These are the famous cedars of Lebanon that were used to build King Solomon’s palace. While their “official” hardiness is the same as the Atlas cedars, to zone 6, there is a small tree growing in the Denver Botanic Gardens. They’re very slow growing, but given enough time it should reach a mature size of 60 feet high and wide, or even larger.
So what about all those other cedars?
Most “cedars” that aren’t in the genus Cedrus don’t have needles. Those in the cypress family have leaves that are scale-like. There are numerous genera; the most commonly planted are Cupressus (cypress), Thuja, and Juniperus. Cupressus and Thuja both have branches that form flat plates, with all the scales in a single plane, while juniper branches are more three-dimensional.
It would be wonderful if everybody knew the difference between true cedars, cypress, junipers, and thuja/arborvitae. Horticulturalists could provide homeowners with better garden advice and garden centers would have fewer confused or upset customers. At least, you’ve got them all straight now. Right?