Picea smithiana, commonly called Morinda spruce (also Western Himalayan spruce in reference to its geographical range) is a tall, pyramidal, needled conifer with horizontal branching and drooping branchlets that typically grows to 70-100′ (occasionally in the wild to 200′) tall. It is native to the western Himalayas from Afghanistan to Nepal and Tibet.
I. Appearance and Characteristics
Picea smithiana is a species of evergreen tree in the family Pinaceae family. It is referred to by the common names morinda spruce and West Himalayan spruce, and is a spruce native to the western Himalaya and adjacent mountains, from northeast Afghanistan, northern Pakistan, India to central Nepal. It grows at altitudes of 2,400-3,600 m in forests together with deodar cedar, blue pine and pindrow fir.
Picea means ‘pitch’, and is derived from the ancient Latin word of the same meaning, pix. The name is in reference to the sticky sap produced by members of this genus.
Smithiana is named for James Edward Smith, an English botanist and the founder of the Linnaean Society.
Picea smithiana is a large evergreen tree growing to 40–55 m tall (exceptionally to 60 m), and with a trunk diameter of up to 1–2 m. It has a conical crown with level branches and usually pendulous branchlets.
The shoots are pale, buff-brown, and glabrous (hairless). The leaves are needle-like, the longest of any spruce, 3–5 cm long, rhombic in cross-section, mid-green with inconspicuous stomatal lines. The cones are broad cylindrical-conic, 9–16 cm long and 3 cm broad, green when young, maturing buff-brown and opening to 5–6 cm broad 5–7 months after pollination; the scales are stiff and smoothly rounded.
Morinda spruce is a popular ornamental tree in large gardens in western Europe for its attractive pendulous branchlets. It is also grown to a small extent in forestry for timber and paper production, though its slower growth compared to Norway spruce reduces its importance outside of its native range. The name morinda derives from the tree’s name in Nepali.
II. How to Grow and Care
Sunlight
Morinda spruce is shade-tolerant, so it doesn’t need much direct sunlight to grow. From spring through early summer, it’s best to expose the tree to light for a duration of over 6 hours a day, but a lack of light for a short time won’t affect its growth. In summer, when sunlight is harsh, it’s best to shade small trees grown outdoors to protect them from long-term, blazing light. If they are potted indoors, move them to a cool, shaded place.
Temperature
Morinda spruce likes cool and moist climates. The ideal temperature range for tree growth is 4 to 18 ℃. It’s hardy and tolerant of temperatures as low as -30 ℃, but young trees and tender branches are less cold-resistant.
Morinda spruce likes moisture, it has good adaptability and is slightly drought-enduring. During the spring and summer growing seasons, the tree prefers higher air humidity (70-80%), while in the fall and winter, lower air humidity (55-65%) can help it grow more sturdy.
Watering
After transplanting morinda spruce, water consecutively 5-7 times, once every 5-7 days. Mix a little rooting powder in the water; this will help the roots grow. During daily care, keep the soil moist but avoid leaving standing water, as this may cause the roots to rot. In general, water once every 10 days. If the leaves soften and droop, increase the watering frequency. The amount of watering can be adjusted depending on the weather conditions.
Soil
Morinda spruce grows well in fertile, deep, well-drained, slightly acidic soils. The best soil pH range is 5.1-7.3, making both sandy soil or slightly clay-like soil good choices. As the tree grows slowly and has a long life span, the soil layer should be about 70 cm thick. If barren, the soil can be improved by adding nutrient soil or organic manure.
Fertilizing
Applying enough base fertilizers before transplanting can provide nutrients to morinda spruce over a long period of growth. In the first year after transplanting, the nutrition-absorption ability of the tree’s roots is not very strong, so apply nitrogen and phosphorus fertilizer every 2 weeks. In the fall, apply a little potassium fertilizer to help the trunk grow thick and sturdy. After the plant matures, it’s best to fertilize it in spring and summer and only fertilize 2-4 times a year. In late fall, morinda spruce slowly enters dormancy, so fertilizing should be reduced and stopped by the end of fall.
Organic fertilizer is the best choice for this slow-growing tree variety. It contains a full set of nutrients that can be utilized continually and reliably. It can also help optimize the soil texture and benefit the plants’ growth. If the soil turns dry after fertilizing, water promptly.
Planting Instructions
To grow morinda spruce in a yard, purchase seedlings and transplant them in early spring. Get the planting pit ready one week before transplanting; its diameter needs to be about 20 cm longer than that of the root ball and have a depth of about 15 cm deeper. It should be no less than 6 m away from other plants. Add organic fertilizers to the bottom of the planting pit before transplanting and mix them well with the soil.
Place the seedling vertically into the pit, shovel 2/3 of the soil back, and water thoroughly once to make sure the moisture around the plant’s roots is sufficient. Then, fill the pit fully up with soil and water again. Stomp the soil firmly and keep the pit surface level with the ground. If it’s often windy at the planting site, support the young tree with wood sticks or metal poles in case a strong gale threatens to tilt it or knock it down.
Indoor potted morinda spruce can be directly purchased. The tree grows slowly and usually doesn’t require repotting. Repotting is only necessary if the needles turn yellow and fall off the tree, the roots around the pot brim or at the bottom wither and dry up, or the soil in the pot compacts. Move the majority of the original soil to the new pot with the plant, and add small amounts of organic fertilizers and new soil to provide more nutrients for its growth.
Pruning
Morinda spruce has lush terminal buds. The tree usually takes on a beautiful triangular shape and does not require pruning in general. When overly pruned, its incisions secrete rosin excessively which affects the tree’s normal growth. It’s best to trim off overly dense, diseased, and dried branches during the plant’s winter dormancy. Prune and beautify the treetop in early spring when buds sprout. About 1/2 of the young branches can be pruned off to create your desired shape. For large, mature trees, it’s a good idea to prune off all the branches on the lower trunk to reduce nutrition consumption.
When growing morinda spruce for Christmas decorations, you need to control height and width. Prune the treetop and lateral branches appropriately short and continue to cut the newly-grown buds short, as well. Repeat this process many times. Seal pruning incisions with wax or duct tape to keep rosin from effusing.
Propagation
We can propagate morinda spruce by cutting. It’s difficult for morinda spruce to grow roots, so the cutting selection is very important. Choose robust, year-old branches in the summer and cut off 10 to 20 cm from them. Dip them in a rooting solution for a while, and insert them into the soil that has been sterilized and wetted. Keep the branches 20 to 30 cm apart from one another and keep the soil moist. When they root, transplant them outdoors by the early spring of next year.
III. Uses and Benefits
Morinda spruce are a group of coniferous trees that are of great value to humans in many ways. The wood is used in everything from housing and frame construction to papermaking and crafting musical instruments. Most species grow in handsome, conical shapes, making them popular ornamentals. Many boreal and temperate high-altitude forests around the world are also comprised largely of morinda spruce, making them tremendously ecologically important.
