Swiss Stone Pine is a native evergreen tree to mountain areas in central Europe from the Alps to the Carpathians. It has more of a slow-growing nature and overall is more of a medium-sized pine. The Swiss Stone Pine tree has a narrow pyramidal shape in its youth, and then gradually becomes more round and open as it matures. Soft, dark green to blue-green needles. Short-stalked, oblong cones are greenish-purple when young, and then mature to a purplish-brown color.
I. Appearance and Characteristics
Pinus cembra, also known as Swiss pine, Swiss stone pine, Arolla pine, Austrian stone pine, or just stone pine, is a species of pine tree in the subgenus Strobus.
The Swiss pine 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 mature size is typically between 25 meters (82 ft) and 35 meters (115 ft) in height, and the trunk diameter can be up to 1.5 meters (4.9 ft). However, it grows very slowly and it may take 30 years for the tree to reach 1.3 meters (4.3 ft). The cones, which contain the seeds (or nuts), of the Swiss pine are 4 centimeters (1.6 in) to 8 centimeters (3.1 in) long. Cones take 2 years (24 months) to mature. The 8 millimeters (0.31 in) to 12 millimeters (0.47 in) long seeds have only a vestigial wing and are dispersed by spotted nutcrackers. The species is long-lasting and can reach an age between 500 and 1000 years.
In its natural environment, this tree usually reaches reproductive maturity at the age of 50 years (even 80 years, if the conditions are more extreme).
The very similar Siberian pine (Pinus sibirica) is treated as a variety or subspecies of Swiss pine by some botanists. The Siberian pine differs in having slightly larger cones, being more massive (taller, wider trunk), having a faster growth rate and needles with three resin canals instead of two as in the Swiss pine.
The Swiss pine grows in the Alps and Carpathian Mountains of central Europe, in Poland (Tatra Mountains), Switzerland, France, Italy, Austria, Germany, Slovenia, Slovakia (Tatra Mountains), Ukraine and Romania. It typically grows at 1,200 metres (3,900 ft) to 2,300 meters (7,500 ft) altitude. It often reaches the alpine tree line in this area.
Swiss pine associates with numerous species of mycorrhizal fungi from a young age, usually from the genus Suillus. This symbiosis improves the tree’s growth and survival rate.
II. How to Grow and Care
Sunlight
Swiss stone pine thrives under full sun exposure, which is instrumental for its growth and health. The ideal light intensity for swiss stone pine consists of direct sunlight for the majority of the day, ensuring robust growth. Though swiss stone pine has a tolerance for partial sun, deviations from full sunlight can lead to suboptimal growth and reduced health vigor. Adaptive traits of swiss stone pine, such as needle adjustments, help it cope with varying light levels. When planted outdoors, swiss stone pine should be positioned in locations that receive ample sunlight, avoiding heavily shaded areas to align with its natural light preferences.
Temperature
The swiss stone 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
Thriving in alpine and subalpine regions, swiss stone pine is well-adapted to environments with moderate moisture. It displays a preference for consistent hydration but can withstand brief periods of dryness. In its natural habitat, swiss stone pine benefits from snowmelt and occasional rainfall, translating to a need for watering once every 1-2 weeks in cultivation. Given its outdoor growth habit, swiss stone pine particularly excels in climates where the cold season ensures adequate soil moisture without the risk of waterlogging.
Soil
Pinus cembra prefer 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.
Manures and mulches
Mulching with ordinary well-rotted barnyard manure in late autumn affords much stimulus to growth. By the following spring the manure will be in a desiccated condition and can be incorporated with the soil. A heavy mulch of old straw, rotten hay, or any similar material over the roots, and this was maintained throughout the entire growing season is beneficial to the plants in a more or less juvenile condition.
In many cases manure is not obtainable. In such an event, newly moved plants should be heavily mulched with rotten straw, rotten hay, or any similar rubbish for a few years until they become established. The frequent stirring of the ground over the roots subsequently will conserve sufficient moisture.
An area extending from the stem to one to two feet beyond the branches, stirred up with hoe and rake perhaps five or six times throughout the growing season, is very beneficial in conserving the moisture around the roots.
Planting Instructions
Swiss stone pine is best planted in early spring. Ideally, use healthy and vigorous seedlings with soils balls, as this can greatly improve the survival rate. In the case of many lateral roots, the deep main root can be cut. Otherwise, the root system should be protected to avoid damage.
Plant in a high, dry, well-drained, and well-ventilated place, with loose soil. In low-lying places with accumulated water, or places with sticky soil, try building a platform or changing the soil before planting. The planting pit should be treated with a basal fertilizer before planting. Newly planted large seedlings should be supported to prevent them being blown down by the wind. Before planting, excess branches should be pruned off. Protect the plant’s shape from damage as much as possible, as this will help to restore growth at a later stage.
Ideally, plant indoor potted plants in the spring, and repot every two or three years in the late fall or early spring. Repotting too frequently will lead to the death of the plant. If the plant is growing weakly, find out the cause of this and change the flowerpot soil, or replant in a larger pot.
Cut back on water before repotting, so as to keep the soil slightly dry. Remove the soil ball from the pot, keeping it whole, and then prune away any old roots from the bottom and sides. Remove some of the old soil from the middle of the soil ball, replace with new soil, apply a small amount of basal fertilizer, and then cover the plant with new soil. Ensure a suitable pot size – a deep pot will easily accumulate water, leading to root rot.
Pruning
Removal of the lower branches of Arolla 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
Native to the high elevations of Europe, swiss stone pine is well-regarded for its stately growth and durable wood. To propagate swiss stone pine, sowing is the most effective method. Start by procuring fresh seeds after the cones have ripened, then stratify them to overcome dormancy. Seeds should be sown in deep containers to accommodate the long taproots and kept under partial shade with consistent moisture. Seedlings require careful attention to prevent damping off, and once established, transplanting must be done with care to minimize root disturbance for successful establishment.
III. Uses and Benefits
- Ornamental uses
Swiss pine is a popular ornamental tree in parks and large gardens, giving steady though not fast growth on a wide range of sites where the climate is cold.
It is also a species that is often used in bonsai.
- Culinary uses
Pine cones cut into slices are used to flavor schnapps, which are then sold as “Zirbenschnaps” or “Zirbeler” schnapps.
- Other uses
The wood is the most used for carvings in Val Gardena since the 17th century.