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Pines: Trees with Personality
by Lesley Reynolds
November 11, 2001


My home city of Calgary is renowned for the splendid specimens of dark green or silvery-blue Colorado spruce (Picea pungens) that grace the city's urban parks and gardens. But as beautiful and reliable as these impressive evergreens are, they can overwhelm all but the largest gardens, frequently blocking sunlight from neighbouring trees, shrubs, and perennials. True, dwarf spruce are available, but why not try a more unusual evergreen—a hardy and beautiful pine.
Pines (Pinus spp.) are trees with personality. Many are open and asymmetrical in form, or grow in twisted shapes quite unlike the regular, dense silhouettes of spruce trees. There are over 100 Pinus species native to the Northern Hemisphere, ranging in size from small shrubs to stately tall trees. They often grow in challenging locations—in high mountains, on dry windswept slopes, or in poor soil. 
Pines are identified by their long needles arranged in clusters of two, three, or five, each cluster encased in a papery sheath at the base. The seed cones, which usually mature in two years, may be round, conical, or even banana shaped. 
Several pine species are well-adapted to prairie growing conditions, and nurseries are now bringing in an increasingly large selection. Here are some of the best choices:

  • Swiss stone pine (Pinus cembra) is native to the mountains of central Europe and Asia. A slow-growing, dense pine, it has a columnar to pyramidal shape when young, becoming more open and rounded with age. It will eventually reach a height of 12 m with a spread of 4.5 m. The flexible 13-cm needles, grouped in bundles of five, are dark green above and bluish-white underneath. The Swiss stone pine has smooth grey bark and deep blue-violet cones up to 8 cm long that remain on the tree for three or four years before dropping. The name "stone" refers to the large edible seeds, relished by birds and squirrels. Pinus cembra 'Nana' is a dwarf cultivar, reaching only 3 m in height.

  • Scots pine (Pinus sylvestris) is pyramidal when young, becoming more open and irregular when mature. It will grow to 15 m in height with a spread of 8 m. The bark on the upper trunk and branches peels to reveal light orange inner bark. It bears twisted blue-green needles grouped in pairs and curved cones growing on short stems. Since Scots pine has a deep tap root it may be successfully underplanted with small shrubs or perennials. Cultivars include: 'Fastigiata', a columnar form; 'Viridis Compacta', a dwarf cultivar; 'Hillside Creeper', a useful groundcover only 60 cm tall and spreading 3 m; and 'French Blue Scotch', a large blue-needled tree.

  • Mugo or Swiss mountain pine (Pinus mugo) is a popular hardy species frequently used for foundation plantings and rock gardens. Extremely variable in size, mugo pines are usually multi-stemmed with dense dark green needles in bundles of two. Gardeners with limited space should select the dwarf form, Pinus mugo pumilio, or dwarf mounding or spreading cultivars, among them 'Mops Mugo', 'Gnom', 'White Bud', and 'Slowmound'. Be aware that even small varieties are notorious for growing larger than expected. Keep mugo pines compact by removing half of the new growth on each growing tip, or candle, in late spring, just before the needles have opened. If you yearn for a larger mugo pine, Pinus mugo rotundata grows to 3 m, while Pinus mugo rostrata (also called Pinus mugo uncinata or Pinus uncinata) is a single-trunked variety growing up to 20 m.

  • Pinus flexilis, the limber pine, is a drought tolerant species native to hot, dry, rocky terrain in British Columbia, Alberta, and North Dakota. Frequently multi-stemmed, the slow-growing limber pine has blue-green needles in bundles of five, grey bark, and light-brown cones, and will reach 8 m tall and 20 m wide. Extra Blue is a silvery blue cultivar.

  • Bristlecone pine (Pinus aristata), which will eventually grow to 12 m tall and 7.5 m wide, is an extremely slow-growing pine with a fascinating twisted or irregular form. Specimens have been discovered in the southwestern United States that are approximately 4700 years old. The dark green needles, clustered in groups of five, are flecked with white resin.

Pines require a sunny location and average well-drained soil. When planting pines take care that the root ball is not damaged or the fibrous roots exposed to air. Water well after planting and provide winter protection with organic mulch around the root area until the tree is well-established; no fertilizing is necessary. Pines do not require pruning, although they are often skilfully shaped to enhance a particular garden scene or to provide a symbolic reference in Japanese gardens. 
Mature pines will often self-prune lower limbs and shed older needles close to the trunk. This is perfectly normal and no cause for alarm. 
Versatile pines offer many textures and forms; there is a species or cultivar to suit every garden. Swiss stone pine, Scots pine, limber pine, and bristlecone pine are all splendid feature trees for all average to large sized city gardens. Gardeners with tiny lots can opt for dwarf cultivars, which are also ideal choices for rock gardens.
In large gardens combine pines with deciduous trees bearing contrasting foliage, or those with bright fall color, such as Amur maple (Acer ginnala) or mountain ash (Sorbus spp.). 


 

Email: lreynolds@saltspring.com
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