Calocedrus decurrens: California Incense-Cedar

Introduction

This stately native evergreen tree slowly grows straight up in a very narrow cone or columnar shape to a height of 70- to 100-feet or more in the wild, 40- to 60-feet in landscapes, yet is only 8- to 12-feet wide at maturity. The branches—which are densely clothed with flat, shiny, dark green, aromatic needles—extend to the ground and remain on the tree unless shaded-out by other trees, making California incense-cedar ideal for use as a screen, hedge, or windbreak. Small, 1-inch long cones are produced at branch tips and are quite persistent, the seeds providing a welcome treat for many varieties of birds and wildlife. Although growth is slow, California Incense-Cedar trees are extremely long-lived, surviving 500 to 1000 years in the wild. Mature specimens have attractive, brick-red, flaky, furrowed bark.

General Information

Scientific name: Calocedrus decurrens

Pronunciation: kal-oh-SEE-drus deck-ER-renz

Common name(s): California incense-cedar

Family: Cupressaceae

USDA hardiness zones: 5A through 8B (Fig. 2)

Origin: native to North America

Invasive potential: little invasive potential

Uses: screen; hedge; specimen

Availability: somewhat available, may have to go out of the region to find the tree

Description

Height: 40 to 60 feet

Spread: 8 to 12 feet

Crown uniformity: symmetrical

Crown shape: pyramidal, columnar

Crown density: dense

Growth rate: slow

Texture: fine

Foliage

Leaf arrangement: opposite/subopposite

Leaf type: simple

Leaf margin: entire

Leaf shape: scale-like

Leaf venation: none, or difficult to see

Leaf type and persistence: evergreen, fragrant

Leaf blade length: less than 2 inches

Leaf color: green

Fall color: no color change

Fall characteristic: not showy

Flower

Flower color: unknown

Flower characteristics: not showy

Fruit

Fruit shape: elongated, oval

Fruit length: .5 to 1 inch

Fruit covering: dry or hard

Fruit color: brown

Fruit characteristics: attracts birds; not showy; fruit/leaves not a litter problem

Trunk and Branches

Trunk/bark/branches: branches don't droop; very showy; typically one trunk; thorns

Pruning requirement: little required

Breakage: resistant

Current year twig color: green, brown

Current year twig thickness: thin

Wood specific gravity: 0.37

Culture

Light requirement: full sun, partial sun or partial shade

Soil tolerances: clay; sand; loam; acidic; slightly alkaline; well-drained

Drought tolerance: high

Aerosol salt tolerance: high

Other

Roots: not a problem

Winter interest: no

Outstanding tree: yes

Ozone sensitivity: unknown

Verticillium wilt susceptibility: resistant

Pest resistance: resistant to pests/diseases

Use and Management

California incense-cedar is a bit particular as to its growing requirements, being very sensitive to continually wet conditions. But with the right combination of proper humidity and moist soil, California incense-cedar will be quite happy growing in full sun or partial shade with some protection from harsh winds. It is surprisingly tolerant of heat and drought. Pruning is rarely necessary, but trees may be sheared, if desired, to maintain a shorter, denser screen. Beautiful specimens of this tree can be seen growing in USDA hardiness zones six and 7.

Many plants grown seem to be the cultivar 'Columnaris', having a very formal landscape effect. The cultivar 'Compacta' has a dwarf, compact growth habit; 'Aureovariegata' has interspersed sprays of bright yellow foliage.

Propagation is by seed or cuttings (with great difficulty) or grafted onto Thuja occidentalis.

Pests

No pests are of major concern.

Diseases

A serious problem is heart rot; less serious problems are rust and leafy mistletoe.