Native to the Atlas Mountains of northern Africa, all atlas cedars (Cedrus atlantica) have blue-green needles in shades from darker, mostly green, to silvery-blue. Those with the bluest needle colors, typically called blue atlas cedars, are grouped into the Glauca group, from the Latin word "glaucus," meaning covered with gray bloom. Two dwarf varieties fall into this category, "Horstmann" (Cedrus atlantica "Horstmann" ) and weeping atlas cedar (Cedrus atlantica "Pendula").
Dwarf conifers of all types are not necessarily small plants -- the term has a somewhat loose definition. While they do grow much smaller than their full-size counterparts and at a much slower pace, it's best to think of them as compact, but large shrubs. Unlike incense cedars (Calocedrus decurrens), which grow in U.S. Department of Agriculture plant hardiness zones 5 through 8 with flat, scalelike needles, atlas cedars, which grow in USDA zones 6 through 9, have needles growing in tufted clusters.
While a standard atlas cedar grows up to 60 feet tall at a rate of 12 to 24 inches each year, "Horstmann" grows only 6 to 8 inches each year and reaches from 10 feet tall after 10 years. "Horstmann" has a compact, dense form typical of dwarf conifers, as compared to the more open and angular growth form of a standard atlas cedar.
Weeping Atlas Cedar
Often grown in a container or as a specimen plant, weeping atlas cedar has branches with a draping, downward growth habit. While taller than "Horstmann," weeping cedar is still considerably smaller than a standard cedar, growing up to 20 feet tall at a growth rate of 12 to 36 inches each season. Weeping atlas cedar's interesting, ornamental form also makes it a favorite as a subject for bonsai.
Growing Blue Atlas Cedars
Atlas cedars thrive in full sun or partial shade in either moist or dry soil. They need watering every two to three weeks when young, are drought-tolerant once they mature and are tolerant of soil types from highly acidic to slightly alkaline. To ensure your dwarf tree stays small, remove any shoots that look as though they have reverted back to the original species, such as those growing faster than others or those with a different color.