Picea pungens 'Koster' (Koster Colorado Spruce or Koster Blue Spruce)


Michael's Opinion

A beautiful evergreen good for mass planting or to compliment a conifer garden as well as being very low maintenance.

Botanical Information

FamilyPinaceae
GenusPicea
Speciespungens
Cultivar'Koster'
CategoryWoody
TypeTree (evergreen)
References
Pronunciation

Details

USDA Hardiness Zone3 - 7
USDA Hardiness Ref.
Canadian Hardiness Zone4b - 6b
Canada Hardiness Ref.
RHS Hardiness Ref.
Temperature (°C)-40C - ( -12C)
Temperature (°F)-40 - 10 F
Height9 - 18 m
Spread3 - 6 m
GrowthMedium

Description and Growing Information

General DescriptionA small to medium sized evergreen. Aesthetically desirable due to its brilliant silver/blue tinge to the needles and most commonly used as Christmas trees.
ID CharacteristicMedium sized evergreen tree with a pyramidal shape to it. It has a horizontally thick branches that go to the ground. Also has evergreen style pin leaves that have a blue/grey tinge to their colour as well as interesting grey bark.
ShapePyramidal.
LandscapeAesthetically pleasing to the eye, they can be used as a center piece or possibly as a distraction point. Also a good grouping plant and a wind break.
PropagationGrafted onto a seedling understock that is done in January or February inside a greenhouse which is then placed under lath or lined out in the spring. Seeds require no pre-treatment.
CultivationVery adaptable as well as more drought tolerant then other Picea. Prefers rich, moist soils and full sunlight.
PestsVulnerable to spruce gall aphids as well as Cytospora canker, which can infect the lower branches.
Notable SpecimensThe University of Western Ontario, London, Ontario, Canada.
HabitatHorticultural origin.
Bark/Stem DescriptionScaly bark with a purple/greyish colour to it. Although it is scaly, it is also soft.
Flower/Leaf Bud DescriptionLong pointed, broadly conical to nearly spherical buds. Buds are yellow/brownish with loosely appressed scales and a blunt re-flexed apex.
Leaf DescriptionLeaves are blue/greyish and are needle like. They are very thick and sharp as well as 4 sided. Leaves are covered in a glaucous wax and are arranged in a radial pattern. Leaves get to be 7 - 14 cm long.
Flower DescriptionMonoecious flowers with a green or purple pistillate in colour.
Fruit DescriptionPicea pungens are conifers and they produce cones.
Colour DescriptionLeaves are blue/greyish year round with purple/greyish bark along with orange and brown shoots.
Texture DescriptionThick, waxy, and sharp leaves as well as soft scaly bark.

Photographs