If you are looking for a unique, eye-catching tree to grab attention in your landscape, consider planting a blue Atlas cedar. A needled evergreen native to the Atlas Mountains in northern Africa, its drooping, twisted branches are filled with whorls of stiff, 1-inch powdery blue needles, producing only a few small cones that grow upright on the branches in the springtime. It can be trained and shaped as it grows and can be molded into cone, oval, cylinder, or "weeping" shapes. In its natural growth habit, it is pyramidal in shape when young, but as it ages it develops a flat top with horizontal branches.
The blue Atlas cedar has a slow-to-moderate growth rate (1 to 2 feet per year). It's best planted in the spring or fall as a container plant or ball-and-burlap specimen (it does not take well to being transplanted) and is generally easy to care for, making it a true favorite of landscape architects and gardeners alike.
|Common Name||Blue Atlas cedar, Atlas cedar|
|Botanical Name||Cedrus atlantica|
|Plant Type||Needled evergreen tree|
|Mature Size||40–60 ft. tall, 30–40 ft. wide|
|Sun Exposure||Full, partial|
|Hardiness Zones||6–9 (USDA)|
Blue Atlas Cedar Care
Planting and caring for a blue Atlas cedar is fairly straight-forward and is mostly dependent on choosing the right spot for the tree in your yard—an open area with plenty of space and no competing trees or shrubs. Beyond that, the blue Atlas cedar is very adaptable and can thrive in a variety of soil and watering conditions.
It's a good idea to stake the blue Atlas cedar until it's established—if you skip this step, it's likely that the tree will end up growing close to the ground. Its roots are considered "established" once a season has passed, and it can be allowed to grow freely at that point, or continue to be staked in a variety of positions to modify its shape.
In order for the blue Atlas cedar to thrive, it's best planted in a spot in your lawn or landscape that receives at least six to eight hours of full sun a day. That being said, the tree can withstand a bit more shade when planted in areas of the country that receive warmer weather, though it should never be planted in full shade.
The blue Atlas cedar does best in well-drained, somewhat acidic soil, though will happily tolerate neutral and slightly alkaline soils. Keep in mind that the tree should be planted in a spot that boasts a deep and wide swath of soil—its roots run deep, and its branches are quite expansive, so it will need room to grow or its size will suffer. The tree can thrive in a variety of soil mixtures, including loamy, sandy, or clay—provided the soil doesn't retain too much moisture; this tree hates to have "wet feet."
The blue Atlas cedar requires consistent and deep watering as its roots become established in your garden or landscape, or for at least the first year of its life. Once established, the tree is fairly drought tolerant, though it should still be watered with some frequency if the weather has been particularly hot or dry.
Temperature and Humidity
This is a tree suited only for the moderate conditions of USDA zones 6 to 9. Within this range, the blue Atlas cedar can handle a myriad of temperature and humidity conditions. It's a good idea to shelter young trees from exposure to strong winds, which can bend or break its limbs.
Though not a necessity for adequate growth, the blue Atlas cedar can benefit from the application of a balanced fertilizer at the beginning of its growth season each spring.
Types of Blue Atlas Cedar
The purse species of blue Atlas cedar generally will have decidedly bluish-gray needles and a shape that is pyramidal when young but gradually transforms into a flat-topped tree with long horizontal branches. But there are a number of popular cultivars that offer some variety in color and shape:
- 'Argentea' has silvery-blue needles.
- 'Aurea' is an unusual variety with yellowish needles.
- 'Fastigiata' is a narrow, columnar form of the tree with bluish-green needles.
- 'Glauca' has a decidedly conical growth habit
- 'Glauca Pendula' has drooping branches and blue-green needles.
Pruning Blue Atlas Cedar
Though the blue Atlas cedar can be pruned slightly to keep it from encroaching on nearby sidewalks or garden plots, it is largely discouraged as this can ruin the wild, eccentric natural shape of the tree. Prune only to maintain or keep the shape of your blue Atlas cedar tree, and do so in early spring before the new growth starts for the season. Be sure to keep at least a portion of the young growth on the tree, and never removed more than a third of the tree's overall density.
Propagating Blue Atlas Cedar
Blue Atlas cedar is difficult to propagate by vegetative means, so the the more common method is by harvesting seeds from the dried cones (see below).
How to Grow Blue Atlas Cedar From Seed
Here is a time-honored method for propagating blue Atlas cedar from collected seeds:
- In fall, collect some ripened cones from mature trees (the cones should be full bodied, but not yet brown), then freeze them just until the scales begin to open up. Shake the cones over a sheet of paper to collect the seeds that fall out. Soak the seeds in water overnight before planting.
- Plant the seeds 1/2 inch deep in a large flat tray filled with a sandy seed starter mix. Set the tray in a sheltered outdoor location; the seeds germinate most reliably if they receive a winter stratification period of roughly one month with temperatures under 50 degrees Fahrenheit.
- Keep the potting mix moist but not wet until seedlings sprout. When the seedlings are large enough to handle, transplant them into individual pots filled with a blend of potting mix and sand.
- Grow the potted seedlings in a protected location for their first two winters (such as in a cold frame).
- Plant the seedling into the landscape in the spring after its second winter in the pot.
Within its hardiness range, blue Atlas cedar does not require any cold protection for winter, but young, sparse trees may need protection against harsh winds, which can be provided with screens or tents made from burlap and stakes.
Young trees can also be susceptible to breakage from winter snow, so it's a good idea to shake off the snow after heavy snowfalls.
Young trees can be heavily browsed by deer, so a tall cage or sturdy wire is a good idea to protect them from hungry deer in the winter.
Common Pests & Plant Diseases
Luckily, the blue Atlas cedar tree is considered to be fairly pest and disease-free, so you won't have to do much to ensure its health and vitality. If it does come down with a pest, it's likely that it will be scale insects or sapsuckers that damage the tree in their search for insects. Still, it's unlikely that the pests will do serious damage to the tree, and therefore it's rare that pest control methods or treatments are necessary.
It's possible that your blue Atlas cedar may experience root rot if its soil is kept too moist. If you notice the branches or needles of your tree turning brown, step back your watering cadence to allow the roots to dry out a bit between waterings.
Tip blight is an occasional fungal disease caused by several different fungi (Sirococcus conigenus, S. tsugae ,and Kabatina spp), causing branches to die back beginning at the tips. Shake the branches to dislodge affected needles, and carefully rake up debris to remove fungal spores. Tip blight normally runs its course in about a year, but spraying with a fungicide containing mancozeb, copper hydroxide, or azoxystrobin may help prevent infection. Fungicides are best applied as new growth is just beginning in the spring.
Common Problems With Blue Atlas Cedar
Planted in the right location and soil conditions, blue Atlas cedar is remarkably carefree. The most common complaint is that the trees are fairly sparse and messy-looking when they are young. This is entirely natural, so you should avoid the temptation to prune it in an effort to make it look more presentable. Left alone, it will become a much fuller, even picturesque tree within 20 years, and by 50 years of age it can be quite stunning.
How long does blue Atlas cedar live?
This is a long-lived tree that has been known to live up to 150 years.
Does this tree have wildlife appeal?
Dense mature trees offer plentiful cover and nesting sites for a variety of songbirds. Unfortunately, deer also find the bitter-tasting needles and branches nutritious, so in areas with high deer populations, you may need to protect young trees from browsing animals.
How should I use this tree in the landscape?
This tree demands to be used as a specimen tree, given a wide-open space where it can reach its full size and display the gloriously eccentric growth habit found in a mature tree.
Is there a similar tree that is appropriate for my colder climate?
Most true cedars (Cedrus spp.) are best suited for moderately warm climates and are not normally grown in climates colder than zones 5 or 6. However, there are a number of "false cedars" (Calocecrus, Thuja, and Chamaecyparis genera) that include species that can be grown in zones 3 to 5. One good option is Chamaecyparis obtusa (Hinoki falsecypress), which has a similar growth habit to Cedrus atlantica but is reliably hardy up to zone 4.