Norway spruce 'Inversa'

Norway spruce 'Inversa' (Picea abies Inversa) – a cultivar of Norway spruce from the family Pinaceae.

The cultivar was discovered in 1855 by R. Smith in Shropshire (Britain).

It is an evergreen coniferous tree 3-5 (6-8) m in height and up to 2-2.5 m in diameter. Grows slowly, for the first 10-15 years at about 20 cm per year, later – up to 70 cm per year. A weeping form with no central leader. Root system superficial, widely

spreading, strongly branched; on well-drained soil it is deep.

Branches and shoots pendulous, hanging down, vertically drooping, the lower ones rest on the ground. The top has a drooping growth habit. The trunk is densely covered with branches. Buds are blunt, reddish-brown, surrounded by two relatively large lateral buds.

Needles short, thick, dark green, glossy.

Cones - 10-15 cm long and 3-4 cm thick, light green, at maturity brownish-brown.

Hardiness zone: 3 (−40°C).

Location/exposure: light-loving but shade-tolerant. In youth it suffers from spring burn. Grows well on fresh, well-drained acidic, sandy or loamy soil. Does not tolerate waterlogging, drought, or soil salinity. Does not tolerate air pollution. In monoculture it can lead to soil acidification.

Planting: Soil mix: topsoil and leaf mould, peat, sand in the ratio 2:2:1:1.

Drainage is made of crushed brick, in a layer 15-20 cm. Planting depth: 50-70 cm. Root collar at ground level.

Care: after planting you can apply 100-150 g of nitroammophoska. During dry periods daily watering of 10-12 L per plant is recommended. Crown sprinkling is also desirable. Loosening is done to a depth of 5-6 cm, with peat not removed but mixed with the soil. Young seedlings need to be winter-covered with conifer boughs.

Pruning: since 'Inversa' has neither a main trunk nor a leader, the shoots immediately begin to grow downward, leaning toward the ground. To raise the tree in height, select one of the shoots and train it upward by regularly tying it to an artificial support. This leader shoot will grow as long as the support is provided. The other shoots will extend to the sides and downward. By regularly pinching them you can shape the crown as desired. Once you decide you no longer want the spruce to grow taller, stop tying the leader shoot, and it will soon droop downward like the others. Thus the gardener can vary the plant's height at will. Some gardeners recommend, after reaching the desired height, cutting the main shoot. This immediately gives a strong stimulus for growth of the lateral branches.

Diseases: Schütte, snow Schütte, fusariosis, stem and root rot, bark necrosis, canker (wound cancer), cone rust, spruce vertun.

Pests: spruce leafroller, spider mite, Sitkhinskaya spruce aphid.

Propagation: propagated by grafting – either onto blue spruce or Norway spruce.

Uses: as a specimen or in group plantings, in rock gardens