At this hot, humid time of year, nothing is more cooling than a glimpse of blue foliage, whose color is a soft reminder of ocean waves, icy crystals or the blue skies of crisp, autumn days. There are many garden plants with bluish foliage, some of which hold their blue color reliably throughout the season and others which fade in the heat. Cedrus deodara, the Deodar Cedar, and Cedrus atlantica, the Atlantic Cedar, are two beautiful conifers that add a cool grey-blue to our hot summer landscapes.
Cedars are large, conical to spreading conifers with fine textured needles that lend them a softer appearance in the landscape than many other conifers like pines and spruces. Native to various parts of Asia and the Middle East, they will reach 40 to 70 feet in height and will spread with age. Cedars are excellent conifers for the southeast where many other conifers will not survive the hot, wet summers. They are tolerant of most landscape conditions, except for extremely wet sites, and are hardy throughout the southeast where they can make wonderful, large, specimen trees.
There are three species of true Cedar available in the landscape and nursery industries (not to be confused with "Eastern Red Cedar", Juniperus virginiana, the native cedar of fence posts and hope chests). Cedrus deodara is often used as a large landscape tree. Young trees are conical but grow to be flat-topped and spreading with age. Frequently, the top dies out with age, contributing to their spreading habit. It is considered the most graceful of the three Cedars treated here, with pendulous branching and very blue foliage, especially in youth. You may especially notice the Deodar Cedar in mid-summer, not only for its refreshing bluish foliage but because of its light blue-grey, upright cones, swelling as they mature, which decorate these trees like special Christmas ornaments. 'Shalimar' is an especially good, hardy cultivar introduced by the Arnold Arboretum.
Cedrus atlantica, the Atlantic Cedar, has thicker, stouter needles than C. deodara and the needles of the species are a bit greener. As a young tree, the habit is much more open and stiff which becomes flat-topped with age, assuming very picturesque, horizontal branching. There are two cultivars of Atlantic Cedar which are widely used and very beautiful. C. atlantica'Glauca' is strikingly blue (although there can be a certain amount of variation in this from source to source) because the needles are covered with an extra thick waxy layer. C. atlantica'Glauca Pendula' is an extremely weeping form of the blue'Glauca'. The branches of this cultivar will cascade from an arbor like a waterfall and there are many beautiful trained specimens across the country. At The NCSU Arboretum (now the JC Raulston Arboretum), a lovely plant of this cultivar drapes the entrance of the Arboretum's Visitor's Center.
A third Cedar available in the trade is Cedrus libani, Cedar of Lebanon, which is indeed the famous Cedar of Lebanon. The foliage is much greener than its two cousins to the point of looking almost black in bright sun. It grows from an openly pyramidal tree when young to a flat-topped, horizontally spreading, very striking tree. It is an incomparably beautiful tree, once seen, rarely forgotten. Unfortunately, this is not an easy tree to grow-requiring a pollution-free, dry, sunny location with well-drained, loamy soil. There are a number of good cultivars. 'Argentea' is a silver-blue form, 'Pendula' is a weeping form that is often grafted to produce a small weeping specimen, var. brevifolia (the Cyprus Cedar) is more diminutive than the species in all its characters, var. stenocoma is an extremely hardy form with an especially stiff, formal habit, and 'Sargentii' is a dwarf form with especially long foliage.
All Cedars can be propagated from cuttings taken fall, treated with rooting promoter and rooted under mist. Cedrus libani is perhaps the most difficult to root but can also be propagated from seed as the other Cedars can. Seed exhibits little or no dormancy but a cold treatment for 2 weeks at 40F has been recommended by Dr. Michael Dirr to improve germination. Cedars make beautiful structural and sculptural trees for landscapes that can afford them a little space. Their soft blues and greys create a halo of cool like a distant mountain range against our city horizons. Consider planting a Cedar tree as a specimen in the garden to bring calm majesty to the southern landscape.