Species: Serbian Spruce - Picea omorika
By Ricky Bates
Department of Horticulture, Penn State
Ask any gathering of conifer enthusiasts to list their favorite spruce and chances are good that Picea omorika (Serbian spruce) will take first or second billing, along with Picea orientalis (Oriental spruce). While there may be some debate about which should be considered the most handsome, one thing is certain: Serbian spruce deserves wider use in our landscapes.
Introduced to cultivation in the late 1800's, Serbian spruce is native to a small region of limestone mountains along the upper Drina river of Bosnia and Serbia, in Southeastern Europe. In cultivation, substantial variation in form does occur from seed. While I have observed many broadly pyramidal specimens, most have a slender trunk and short ascending or drooping branches forming a narrow, very graceful, spire-like habit. The tree has a moderate growth rate of up to 12 inches per year and generally will attain a height of 50 to 60 feet by 20 to 25 feet spread. Identification is made easy by its unique habit and needle characteristics. Serbian is one of the few spruces with flat needles like a hemlock, not the four-sided needles of most spruces. The short, ½ inch to 1 inch long needles are lustrous dark green above while the underside has two broad, white stomatal bands. These bands collectively standout, creating a unique silvery contrast that is very effective when the upswept branches move in the wind. Cones are egg-shaped to 2½ inches long and pendulous, blue-black when young, cinnamon when mature.
Hardy to Zone 4, Serbian spruce grows well in full sun to partial shade on sites protected from winter wind. If grown in too much shade the tree becomes thin and leggy and will not thrive. While Serbian prefers a rich, moist but well-drained soil, most sources indicate it will tolerate a wide pH range, drought-prone soil, and urban conditions. It is considered to be one of the most adaptable spruces, quite a claim given the hardiness and tenacity of species such as Norway and Black Hills spruce. Serbian transplants well in spring or fall from containers or as a B&B plant and establishes quickly under a variety of landscape conditions.
Propagation is straightforward, as seeds require no pretreatment. However, I have noticed a slight boost in germination percentage when seeds are stratified for up to 3 months at 40°F. Most Serbian spruce cultivars are side-veneer grafted using P. abies or P. glauca as understock.
Few diseases appear to bother Serbian spruce in the mid-Atlantic region. Some sources list aphids, mites, scale and budworm as potential insect problems, however so far there are no reports of these pests significantly affecting the tree in Pennsylvania. The notable exception is White Pine Weevil. This pest will destroy the central leader and can seriously disfigure Serbian spruce if not controlled.
An elegant specimen, Serbian spruce deserves a more prominent place in commercial and residential landscapes. It can be used in groups, as a single specimen, or even as an evergreen street tree. It has utility as a natural screen and selections with a narrow habit are suitable for even small urban landscapes. Serbian spruce represents a welcome alternative to the all-to-common Norway and Colorado spruce.
Name: Picea omorika
Common name: Serbian spruce
Hardiness: Zone 4
Mature height: 50 feet to 60 feet
Mature spread: 20 feet to 25 feet, variable
Classification: Evergreen tree
Landscape use: Specimen, screening, group planting, evergreen street tree
Ornamental characteristics: Short ascending or drooping branches form a narrow, very graceful, spire-like habit; ½-to 1-inch long, flat needles are lustrous dark green above, distinct silvery stomatal bands beneath
Dr. Ricky M. Bates
Assistant Professor of Ornamental Horticulture
Department of Horticulture
Penn State University