Spruce Trees In The Landscape

04-17-2000
Spruce trees which are members of the genus Picea make effective large area landscape plants. They are also effective specimen plants or can be used in mass plantings where space is available. Spruce grow native in the cool-humid northern regions of the country from New England through the Great Lakes to the West Coast.

Most species of spruce are fairly stiff and formal. Their habit is a strong vertical line which can dominate home landscapes. Cultivars have been developed which fit small, intimate landscapes. When young, the trees are thick; while at maturity, the lower branches tend to thin out and die off which reduces their landscape effectiveness.

All spruce are sun-loving plants. Shade or competition from other trees will cause thinning, decline, or death. They should not be used as an understory tree like our native hemlock. Spruce grows best in fertile, moist, yet well-drained soil.

There are a few insect and disease pests associated with spruce. However I find that trees planted in the proper location that are given reasonable care are not as likely to be affected with pests.

Keep in mind that all of the spruce species available, with the exception of smaller or dwarf cultivars, are large specimen plants. They need plenty of room to grow, and they do not respond at all to major pruning intended to keep them smaller. The following spruce are all hardy in Pennsylvania and can function in most landscapes where there is a need for larger trees.

Norway Spruce - Picea abies is native to Europe. It has a shallow root system and seems to grow in a variety of soil conditions and tolerates high water tables rather well. When young, it is a stiff, formal plant; at maturity, this 60 foot tree becomes more graceful with pendulous branches.

Engelmann Spruce - Picea engelmannii is native to the western mountains and was introduced into cultivation about 1862 as settlers moved westward. It is very hardy and forms a dense, narrow, pyramidal tree growing to about 50 feet under cultivation. Specimens in its native habitat might reach 120 feet. It has a somewhat coarse texture with 1-inch long blue-green needles. The plants are quite pest-free, and many plantsmen consider it one of the best spruce.

Probably my favorite spruce would have to be Serbian Spruce - Picea omorika because of its very narrow, pyramidal growth habit and deep green leaf color. The underside of the leaf has a bright, silvery-white line which creates effective contrast with the upper surface. It has an ideal landscape height is about 40 to 50 feet which allows Serbian Spruce to fit many properties. It is native to southeastern Europe where soils tend to be more alkaline and I have found this tree to do well in the clay loams found in many areas of Pennsylvania.

Oriental Spruce - Picea orientalis has a number of properties similar to Norway Spruce. Its branches may be slightly more horizontal, but as the tree matures it too develops pendulous branches. It has a narrow form and often grows to 45 to 55 feet in a landscape. The foliage is a clean, deep green and about one half inch long. Oriental Spruce seems to adapt to a variety of soil types as long as they are not too wet.

Blue Colorado Spruce - Picea pungens glauca is still one of the more popular spruce. Its deep, blue-green to silvery foliage allows it to contrast well in any landscape setting. The mature plants are very stiff with generally horizontal branches. The plants will become quite large with spread of 25 or more feet and heights of well over 50 feet. It does have a few significant pests and since it is a rather common plant I often encourage homeowners to consider another species of spruce to meet their landscape needs.

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**Dr. Robert Nuss is a horticulturist at Penn State. He coordinates all extension horticulture programs. He has bachelor’s, master’s, and doctoral degrees in ornamental horticulture and has been on the Penn State faculty since 1966.