Western white pine or silver pine is a large tree with large pine cones. It grows naturally in the mountains of western United States and is related to the somewhat smaller Eastern White Pine, Pinus monticola, which grows on the eastern side of the United States.
I. Appearance and Characteristics
Western white pine (Pinus monticola), also called silver pine and California mountain pine, is a species of pine in the family Pinaceae.
The species occurs in humid areas of the mountains of the Western United States and Western Canada such as the Sierra Nevada, the Cascade Range, the Coast Range, and the northern Rocky Mountains. It can be found in elevations of 600 to 1,800 meters (2,000 to 5,900 ft) above sea level in eastern Washington and Oregon’s Blue Mountains and 1,800 to 3,100 meters (5,900 to 10,200 ft) on the western face of the Sierra Nevada as far south as the headwaters of the Kern River.
The tree often occurs in forests with fir and hemlock species, especially those which are tolerant of shade. It benefits from disturbances that clear away competing species, including low fires that do not destroy all of its cone-protected seeds. It is also well adapted to poor, rocky soils.
Western white pine is a large tree, regularly growing to 30–50 metres (98–164 ft) tall. It is a member of the white pine group, Pinus subgenus Strobus, and like all members of that group, the leaves (‘needles’) are in fascicles (bundles) of five, with a deciduous sheath. The needles are finely serrated, and 5–13 cm (2–5 in) long. The cones, appearing even on young trees, are long and slender, 12–32 cm (4+3⁄4–12+1⁄2 in) long and 3–4 cm (1+1⁄4–1+1⁄2 in) broad (closed), opening to 5–8 cm (2–3+1⁄4 in) broad; the scales are thin and flexible. The seeds are small, 4–7 mm (3⁄16–1⁄4 in) long, and have a long slender wing 15–22 mm (9⁄16–7⁄8 in) long.
The branches are borne in regular whorls, produced at the rate of one a year; this is pronounced in narrow, stand-grown trees, while open specimens may have a more rounded form with wide-reaching limbs. When mature, the tree has bark that appears to be cut into small, checkered units.
Similar species
It is related to the Eastern white pine (Pinus strobus), differing from it in having larger cones, slightly longer-lasting leaves (2–3 years, rather than 1.5–2 years) with more prominent stomatal bands, and a somewhat denser and narrower habit.
II. How to Grow and Care
Western white pine is a large evergreen tree that thrives in well-drained, acidic soil and requires ample space to grow. Special care points include its susceptibility to white pine blister rust and the need for regular monitoring and potential preventive treatment. It also demands consistent moisture but cannot tolerate waterlogged roots. The combination of disease management and particular soil moisture needs classifies the care for western white pine as difficult.
Sunlight
Western white pine thrives best in conditions of full sun, where it can receive intense and direct light for the majority of the day. This exposure is critical for its robust growth and health, allowing for optimal photosynthetic activity and energy production. Western white pine does display tolerance for partial sun conditions, although such conditions might lead to less vigorous growth and an increase in susceptibility to health issues.
Outdoors, it is recommended to plant western white pine in locations where they will not be overshadowed by taller structures or vegetation. Despite the ability to adapt to less than ideal light exposure, maintaining direct sunlight aligns with the species’ natural habitat and ensures stronger development.
Temperature
The western white pine is mostly native to the northern hemisphere and can withstand many challenging environmental conditions. Tolerant of temperatures ranging between -60 to 50 ℃, making it suitable for hardiness zones 11 and below, this is a plant that grows best in well-drained, deep and moist soil.
Watering
Adapted to its native mountainous terrains, western white pine thrives in conditions where moisture is present but well-drained, reflecting its moderate drought tolerance. Watering practices for western white pine should mirror the natural precipitation patterns it has adapted to, with a schedule of once every two weeks being ideal. This species maintains a balance between hydration and drainage, ensuring resilience in variable environments. As an evergreen plant, western white pine retains its foliage year-round, requiring consistent soil moisture levels to support its continuous growth and needle health, especially when grown outdoors.
Soil
Pinus monticola prefers a well-drained porous gravelly subsoil, overlaid with a light sandy loam. They seem to be particularly happy in a soil underlaid with a porous glacial drift. In cultivation, however, they succeed very well in ordinary well-drained soil. When the plants are set in clay soil, which is often done, the soil should be thoroughly loosened by trenching or subsoil plowing, and well under-drained. Any available humus, wood ashes, and well-rotted manure incorporated in the soil greatly aid in rendering it friable and porous for the roots.
Fertilizing
For western white pine, use balanced nutrition fertilizers to support robust growth. Fertilize mature trees every 2-3 years and young saplings annually, in early spring or late winter. Apply fertilizer evenly, at the recommended label rate, avoiding overdose. Fertilization boosts western white pine’s health, and aids against disease and stress. Adjust feeding with the season; less is needed in dormant periods. Use slow-release granules for sustained benefits. Always water thoroughly post-application to prevent root burn and aid nutrient absorption.
Pruning
Removal of the lower branches of Western white pine is a serious mistake, and, if healthy, they should be retained to the base. Pruning or disbudding can be intelligently performed to add much to the natural symmetry. The extraction or removal, early in spring, of the central or terminal bud, will tend to compel the branches which start from the side buds to spread apart and form a much denser growth. Cutting back the previous year’s terminal growth to a strong bud or branchlet on the main limbs over the tree, if the plant is inclined to be thin in its branching, always produces a much denser lateral growth.
Propagation
Western white pine is renowned for its striking stature and robust nature within its native range. To propagate western white pine, enthusiasts can extract seeds from its mature cones, which require stratification to break dormancy and enhance germination. A well-draining growing medium is essential to nurture the young saplings, ensuring appropriate moisture and protection from harsh environmental conditions. As seedlings develop, gradual acclimatization will promote resilience, preparing them for successful transplantation into their permanent locations.
Transplanting
Transplanting can be done at all times of the year, excepting midsummer when they are in full growth. The best success is secured in spring when the buds begin to swell. From the end of August to the middle of September, if there have been abundant rains and the ground has been well soaked, is a very good time to move the plants. They may be planted late in autumn when circumstances compel it, but there is likely to be a considerable percentage of loss. Their roots are very susceptible to injury from exposure to the air, and the utmost vigilance should be exercised to keep them covered and moist.
III. Uses and Benefits
The gum was reportedly chewed by Native Americans to treat coughs. The pitch was used to fasten arrowheads and coat fishing and whaling instruments. European colonists used both Western and Eastern white pine as softwood lumber. Both species are considered excellent for molding and carving. First the Eastern and then the Western species were used in the building of transcontinental railroads in the late 19th century. In the early 20th century, white pine was used to build houses and make matches.
Western white pine is widely grown as an ornamental tree.
