Conifer Cultivars

A recent trip to the Oregon Garden was a great opportunity to see a great variety of conifer cultivars. Many of the conifers you find in landscaping are cultivars of naturally growing species. What is a cultivar? "Cultivar" is a short version of "cultivated variety." It is a plant selected for some set of desirable characteristics, often a result of careful breeding to accentuate those characteristics. Most garden plants and food crops are cultivars.

There are only about 600 species of naturally growing conifers. However conifer cultivars number in the thousands. The Encyclopedia of Conifers describes over 8000 cultivars. The authors note that there may be over 15,000 conifer cultivars now.

Dwarf cultivars - All photos from the Oregon Garden

Cultivar names: The formal names of cultivars are formed by adding a special name to the Latin name of the species. These names can be in any language and are enclosed in single quotations marks, for example: Picea glauca 'Pendula', a cultivar of white spruce. Cultivars often have common names as well, in this case, weeping white spruce.

Picea glauca 'Pendula'

Variability: Cultivars can look entirely different from their parent species. Like the variety of dogs "cultivated" from the wolf, there may be hundreds of different cultivars developed from a single species of conifer. Over 450 have been produced from one Oregon native: Port Orford cedar (Chamaecyparis lawsoniana). Western red cedar has produced over 40 cultivars.

Origin: Many cultivars originated from naturally occurring genetic variations in a species or from genetic mutations. Others are produced by bud mutations on a normal tree. These can result in color change, different growth patterns, or dwarfing. Bud mutations often produce witches' brooms, a reduced growth form that creates a mass of short branches that often look like a dense bush growing high in a tree.

Cultivars are often reproduced by cloning, for example by growing cuttings taken from a twig. Some are reproduced from seeds, but normal reproduction introduces genetic variability that is often difficult to control.

Cupressus glabra 'Raywood's Weeping'
- a cultivar of Arizona cypress

Features: Conifers often grow to be large trees, not suitable to a small landscaped yard or garden. Many conifer cultivars are dwarfs compared to their parent species. They have been selected because they grow slowly and remain a reasonable small size for years. Many are selected for their unusual color, often showing blue or variegated leaves. Some show unusual growth patterns that people find attractive. A favorite feature is stringy, drooping branches. These cultivars are often named 'Pendula' or 'Weeping'.

One of the best places to see conifer cultivars is at the Oregon Garden. The Conifer Garden there features an extraordinary variety of cultivars that are beautifully landscaped and maintained. Fall and winter is a great time to visit. The conifers look about the same as in spring and summer, and you will avoid the crowds of people. 

Sequoiadendron giganteum 'Pendula'
 - a cultivar of giant sequoia

Abies koreana 'Silberlocke' - a cultivar of Korean fir

Abies koreana 'Piccolo' -  a cultivar of Korean fir

Cedrus atlantica 'Glauca Pendula' - Stretches across the photo and over the trellis

More info
Encyclopedia of Conifers [Caution: Extremely heavy. Lift with legs, not back.]
Bert Cregg: Extension Publications and Conifer Corner articles