How to Grow a Weeping Blue Atlas Cedar

Sun

Full sun produces the brightest blue color and the tightest weeping form. Six to eight hours of direct sun is the minimum for the foliage to develop its signature blue-gray cast. Less than six hours fades the color to dull green and produces weak open growth.

Drainage

The roots rot quickly in soggy ground. Pick a spot on a gentle slope or any high point in the yard. Dig a one-foot test hole and fill it with water. If it drains within a few hours, the spot is fine. If water sits overnight, build a raised mound 12 to 18 inches above grade and plant on top of it.

Soil

Deep loamy soil that holds moisture without staying soggy is the goal. The tree tolerates a wide range of soils as long as drainage is good, including sandy soils that frustrate many other landscape conifers. Work a few inches of compost into the planting area before planting.

Space

Plan for at least 10 to 15 feet of clear horizontal space. The natural sprawl carries the weeping branches outward across the ground, and a tree pushed against a wall or driveway loses the sculptural effect. Pick a focal point in a lawn, on a slope, or beside a path where the form can be admired from a distance.

Watering

Water deeply once a week through the first two growing seasons to help the tree establish, soaking the root zone rather than splashing the foliage. Use a soaker hose or drip ring at the base, since overhead watering on dense blue-gray foliage promotes fungal problems.

From year three onward, Weeping Blue Atlas Cedar is fairly drought-tolerant and gets by on rainfall in most years. A deep monthly soak through extended summer dry spells keeps the foliage looking fresh. Avoid frequent shallow watering, which encourages weak surface roots.

Feeding

Feed lightly. The tree grows slowly by nature, and heavy feeding pushes soft weak growth that floods past the trained form. Apply a balanced slow-release fertilizer in early spring as new growth starts, scattered around the drip line and watered in.

Skip feeding after midsummer so the tree hardens off before winter. A two-inch top-up of mulch each spring, breaking down into the soil over the year, is often enough on its own.

Training the leader

Each year as the trained leader gains height, extend or replace the stake and tie the new growth loosely upward with soft ties. Check ties every spring and loosen any that are starting to bite into the bark. Once the tree reaches the desired final height, stop tying the leader upward and let it weep over with the rest of the canopy.

Shaping the weeping form

Remove any branches that cross other branches, grow straight up rather than weeping, or break the overall outline. Make cuts back to the trunk or a side branch, never leaving stubs. Light shaping in late winter while dormant lets the new spring growth fill in cleanly.

Keep cuts modest each year. A heavy prune leaves bare patches that take years to fill in on this slow-growing tree.

Removing dead or damaged growth

Snow load or wind can break weeping branches in winter. In late winter or early spring, cut any broken branches back to healthy wood at a side branch or the trunk. Dust off heavy wet snow gently in winter before it breaks branches.

Foliage through the year

The short needles emerge silvery blue-gray in spring, mature to a deeper steel blue through summer, and hold their color through winter. The tree is fully evergreen and looks striking even with snow on the cascading branches.

The blue color is strongest in full sun. A tree in less than full sun fades to dull green-gray within a couple of seasons.

Cones and old age

Mature trees, usually after 20 to 30 years, produce upright barrel-shaped cones along the upper branches. The cones start green and turn brown over a couple of years before breaking apart on the tree to release winged seeds. The cones add textural interest but are not the main draw.

Form over time

Each Weeping Blue Atlas Cedar develops its own personality based on how it is trained. A tree staked straight up early becomes a tall narrow column with cascading skirts. A tree allowed to sprawl across a slope without an upright stake becomes a low ground-hugging form. Both are correct, since the form is entirely up to the gardener.

Brown foliage on lower branches

Normal needle drop on inner shaded branches, especially in older trees, which is part of the natural growth pattern. Heavy browning across whole branches usually means drought stress in summer or root rot from a wet site. Mulch the root zone, water deeply during dry spells, and check the drainage if browning persists.

Sticky residue under the tree

Cedar aphids feeding on sap and excreting a sugary residue, which drips onto cars or patios below. A strong spray of water from a hose knocks the aphids off, and horticultural oil sprayed in late winter while dormant prevents the next round. Heavy infestations attract sooty mold, which washes off the foliage with soapy water once the aphids are gone.

Webbing in branches

Bagworms, which build silken cocoons covered in needles along the branches and feed inside. Hand-pick the bags off and drop into soapy water, especially in late winter before the next generation hatches. Bt (Bacillus thuringiensis) spray timed to young caterpillars in late spring controls heavier infestations.

Yellow needles all over the tree

Usually root stress from poor drainage or chronic overwatering. Dig down a few inches to check the soil moisture. If the soil stays wet, build a raised mound around the trunk or stop supplemental watering. Iron deficiency on alkaline soil can also cause yellowing, in which case a chelated iron foliar spray helps.

Broken branches after a storm

Heavy wet snow or ice can snap the cascading branches. Cut broken branches cleanly back to healthy wood at a side branch or the trunk. In future winters, gently brush heavy snow off the branches with a broom before the load grows.

Sap dripping from the trunk

Often borers, especially cedar bark beetles, drilling into stressed trees. Look for small round entry holes weeping sap. Keep the tree well-watered during dry spells to reduce stress, since borers preferentially attack weak trees. Severe infestations are hard to control once advanced.

Tip dieback on cascading branches

Often winter desiccation when cold winds dry out the foliage faster than frozen roots can replace water. Trim back to healthy wood in spring once new growth pushes. A burlap wind screen on the exposed side helps young trees through their first few winters in zone 6.

Fading blue color

Too little sun is bleaching the foliage. The blue cast develops only in full sun. If a neighboring tree has grown in and shaded the bed, prune the neighbor or accept the duller color. Once foliage has lost the blue cast, it does not regain it on the same branches.

Stake tie damaging the trunk

A tie left in place for years bites into the bark and girdles the trunk. Check ties every spring and loosen any that are tight. Use soft fabric or arbor tie rather than wire, and replace ties as the trunk thickens.