Though people call many different conifers "cedars," only members of the genus Cedrus are truly cedar trees. Native species grow all over the world. Cedars are among the sturdiest and most forgiving of trees, able to survive in all kinds of weathers, in poor soil and patchy sunlight, and with irregular watering.
Cedars are evergreens--they don't lose their needles in the wintertime. The needles of true cedars grow in clusters, and the trees bear their seeds in cones. The male catkins produce yellow pollen that's spread by the wind. Most cedar trees will grow to dizzying heights, although horticulturalists have bred a few "dwarf" varieties that will only grow to 20 feet or so.
Atlanta Cedar (Cedrus atlantica)
A slow-growing native of North Africa that eventually will reach 60 feet or more in height and 30 feet at the base, this tree has short, bluish-green or blue needles, depending on the variety. The cultivar Glauca pendula has a weeping habit. Cedrus atlantica is hardy in zones 3 through 10 and needs full sun to flourish.
Deodar Cedar (Cedrus deodara)
Cedrus deodara grows very quickly to 80 feet tall, and spreads to 40 feet at its base. The tips of the branches droop and the leaves are finer than those of most cedars. It will grow well in zones 3 through 10, but it does need full sun, and it can completely overpower a small yard. This is a tree that needs room to be at its best.
Incense Cedar (Calocedrus decurrens)
This tree is an American native that grows from central and southern Oregon, throughout California and into western Nevada, all the way down to northern Baja California. The tree spreads out to a 15 foot base and reaches 75 to 90 feet in height. It has reddish-brown bark and rich green needles.
The incense cedar gets its name from the intense scent it emits during warm weather. It is an exceptionally tough tree, hardy in zones 2 to 10 and able to withstand poor soil and baking heat. In zones 2, 4 through 7 and 10, it needs no supplemental water, nor does it have to be pruned.
Cedar of Lebanon (Cedrus libani)
A native of the Middle East, the cedar of Lebanon grows slowly eventually reach 80 feet in height. The needles are short and bright green when the tree is young; as it ages, the needles darken go gray-green. The tree spreads out as it grows, finally achieving a shape that is nearly as broad as it is tall. Hardy in zones 3 through 10, it requires only routine care and no pruning.