Picea smithiana aka Morinda Spruce

Picea smithiana requires abundant moisture at the roots and prefers consistently moist soil. Water regularly to maintain even soil moisture, especially during establishment and dry periods. The tree is not drought tolerant and will suffer in dry conditions. In cultivation, ensure the soil remains moist but well-drained, as waterlogged conditions can lead to root problems.

Picea smithiana is adaptable to various soil types including light sandy, medium loamy, and heavy clay soils. It tolerates a wide pH range from very acidic to mildly alkaline and can even grow in nutritionally poor soil. The key requirement is good drainage combined with moisture retention. For best results, plant in deep, moist but well-drained soil. The tree prefers slightly acidic to neutral conditions (pH 4-6) but is quite adaptable.

In its native Himalayan habitat, Picea smithiana typically reaches 50-65 meters tall with a trunk diameter up to 2 meters. In cultivation, it usually grows to a more manageable 15-30 meters depending on climate. The tree has a conical crown with distinctive strongly pendulous branchlets that give it an elegant weeping appearance. Growth is initially slow, but established trees can add 60cm annually under favorable conditions. The spread is typically 6-9 meters wide.

Picea smithiana can be propagated from seeds or cuttings. For seeds, sow fresh seed in autumn in a cold frame for best germination; stratification improves results. Keep seeds moist and in light shade. Seedlings are frost-sensitive and need protection. For cuttings, take semi-ripe terminal shoots (5-8cm) in August and place in a frame, protecting from frost. Alternatively, take mature terminal shoots (5-10cm) in September-October in a cold frame; these take about 12 months to root. Note that this species is strongly outbreeding, so self-fertilized seed grows poorly.

While Picea smithiana has no serious species-specific problems, it shares common spruce vulnerabilities. Watch for spider mites, which are a common pest. Other potential issues include spruce budworm, yellow-headed spruce sawfly, eastern spruce beetle, and deodar weevil. Disease-wise, spruces can be susceptible to needle and stem rust, Cytospora canker, and trunk or root rot. The species cannot tolerate atmospheric pollution and is intolerant of maritime exposure. Young plants are particularly vulnerable to late spring frosts.

Picea smithiana is exclusively an outdoor tree, hardy to USDA zones 6-9 (UK zone 7). It thrives in climates with cool summers and struggles in areas with high heat and humidity. The species performs best in oceanic climates like western Europe, particularly around the Italian Lakes. In the US, it should be sited in protected locations, especially in borderline zones. Young plants need protection from late spring frosts and cold, drying winds. The tree resists wind exposure but cannot tolerate maritime conditions or atmospheric pollution.

Picea smithiana is cold-hardy to approximately -17°C to -12°C (0°F to 10°F), corresponding to USDA zone 7. It can tolerate light frost and occasional snow but performs best in climates with cool summers. The tree struggles in areas with high summer heat and humidity. Young plants are particularly sensitive to late spring frosts, as new growth emerges early and is vulnerable to damage. Established trees are more resilient, but protection is recommended for seedlings until they reach about 1.5 meters tall.

Picea smithiana prefers moderate to high humidity levels consistent with its native Himalayan montane forest habitat, where monsoon conditions prevail. The tree struggles in areas with high heat combined with high humidity but appreciates good atmospheric moisture in cooler climates. It thrives in oceanic climates and performs poorly in dry continental conditions. Ensure adequate soil moisture to compensate in drier climates, but avoid waterlogged conditions.

Picea smithiana has modest fertilizer requirements and can grow in nutritionally poor soil. For optimal growth, apply a balanced slow-release fertilizer formulated for conifers in early spring before new growth begins. Avoid over-fertilization, which can promote weak, frost-susceptible growth. Young trees establishing in their first few years benefit most from fertilization. Mature trees rarely need supplemental feeding if planted in reasonably good soil.

Several cultivars of Picea smithiana exist for garden use. 'Ballarat' is a dwarf, spreading shrub originating from a witches' broom, with very slow initial growth. 'Himalaya Hexe' is a dense, slow-growing selection reaching about 1.2 meters in ten years. 'Pakistan' offers a slow-growing habit with dense form. 'Sunray' features golden-yellow foliage, though it has been described as somewhat chlorotic-looking. These cultivars offer alternatives to the massive species type for smaller garden spaces.

Spring is the critical season for Picea smithiana care, as young growth emerges early and is vulnerable to late frosts. Protect young trees with horticultural fleece or by siting in sheltered locations away from frost pockets. Seeds ripen in autumn (October-November), which is also the best time to collect and sow them. Winter requires no special care for established trees within their hardiness range, though young specimens benefit from protection from cold, drying winds.

Several parts of Picea smithiana are edible, earning it an edibility rating of 2 out of 5 on the PFAF scale. Young male catkins can be eaten raw or cooked. Immature female cones can be roasted, with the sweet center being the edible portion. The inner bark can be dried and ground for use as a flour thickener. Seeds are edible raw. Young shoot tips can be brewed into a vitamin C-rich tea, similar to other spruce species. While edible, these are not significant food sources.

Picea smithiana has several practical uses beyond ornamental value, rated 2 out of 5 on the PFAF scale. The wood is used for construction and paper pulp production, though its slower growth compared to Norway spruce limits commercial forestry use outside its native range. The bark is traditionally used for water-resistant roofing material. Resin can be extracted from the tree, and the wood makes good charcoal. The species is highly valued as an ornamental specimen tree in large gardens across western Europe, prized for its elegant pendulous branchlets.

Picea smithiana is wind-pollinated, like all members of the Pinaceae family. The species is monoecious, bearing both male and female cones on the same tree. Pollination occurs in spring when male cones release large quantities of pollen that is carried by wind to the female cones. Seeds typically ripen 5-7 months after pollination, in October to November. Importantly, this species is strongly outbreeding, meaning self-fertilized seed tends to grow poorly, so having multiple trees improves seed viability.