Atlas cedar bonsai

Placement

Cedrus atlantica is a large evergreen conifer from the Atlas Mountains of Algeria and Morocco. As a bonsai it lives outdoors year-round in full sun. Shield it from temperature extremes, in summer as well as winter.

Although the tree is hardy in the ground, its roots are vulnerable in a container: protect the root ball from freezing temperatures and cold wind, especially on young plants. Wait for the first frosts before sheltering it, since cold helps it go dormant. Depending on how harsh your climate is, wrap the pot in insulation, bury it in the garden up to the roots in a spot out of the wind, or move the tree into a cold frame or cold greenhouse, opening it up on sunny days. Do not bring it into a heated room.

The short needles, gathered in tufts on spur shoots, lend themselves well to miniaturization, and blue-foliaged forms such as ‘Glauca’ are especially prized. A young cedar looks like a larch but stays evergreen. It suits formal and informal upright styles, with one or several trunks, in medium to extra-large sizes. Like other conifers, it takes deadwood well: jins and sharis last on its resinous wood.

Soil mix

Cedar comes from dry regions and dislikes excess water, so the mix must drain very freely. A common conifer mix combines equal parts akadama, pumice and lava rock. Sift the akadama, and the lava rock if it is dusty, to keep the mix airy. In a rainy climate, raise the share of lava rock; if you cannot check on watering often, raise the akadama.

Watering

Cedar likes to be kept on the dry side. During the growing season, let the mix dry before watering, then water thoroughly; in hot weather this can mean every day. Above all avoid overwatering, which causes root rot. In winter, do not leave the root ball waterlogged: it would freeze more easily and the roots would suffer.

During the growing season, apply liquid fertilizer every two weeks, or solid organic fertilizer every four to six weeks.

Pruning

Shorten twigs in early spring. Throughout the growing season, pinch new shoots to build denser branching, but never cut the needles themselves. Save the removal of large branches for fall to avoid resin bleeding.

Cedar wounds heal very slowly. Instead of cutting a branch flush, leave a stub and turn it into a jin, or create a shari along the trunk; it looks better than a visible scar. Early spring and late summer are the best times for this work, which should be kept for a healthy, vigorous tree. Then treat the deadwood with lime sulfur, which bleaches it and protects it from rot, and reapply from time to time. Widen a shari gradually over months or years, without cutting off the supply to branches above it.

Atlas cedar has few problems. Watch for aphids and for the fungi Sirococcus and Pestalotia, which cause shoot blight and needle drop: improve growing conditions and use a specific treatment if needed. In an overwatered pot, root rot remains the main danger.

Wiring

Wire young, flexible twigs carefully so as not to damage the bark. Conifers can be wired over much of the year; work preferably during active growth, avoiding heat waves. Copper wire, which is harder, suits conifers well; choose wire about a third as thick as the branch and wrap it at a 45° angle, anchored with at least one turn around the trunk or a neighboring branch. Protect thick branches by wrapping them in damp raffia before wiring.

Wire can stay on for a few months, sometimes six to twelve, but check it regularly during the season and cut it off at every turn before it marks the bark. For old, stiff branches, use guy wires anchored to a strong root, a sturdy branch or the pot. Never wire a weak or freshly repotted tree.

Repotting

Repot a young cedar every two years and an older one every three or four years; an established, refined tree can stay in the same pot much longer. Several windows work: spring before the buds open, or fall; late summer, after the last flush of growth, suits it especially well. Disturb the roots as little as possible: do not remove all the old soil at once, and prune roots only lightly, because cedar can drop older needles after root disturbance. Afterward, protect it from wind, scorching sun and frost.

It is propagated from seed in spring, after about three weeks of moist cold stratification at 32–34 °F; cuttings and air layers rarely succeed. Its garden care is covered in the Atlas cedar plant profile.