Blue Spruce – Picea pungens
Common name: Blue Spruce/Colorado Blue Spruce
Scientific name: Picea pungens
Introduction: Blue Spruces are a non-UK native evergreen conifer that has a life span between 600-800 years. They are native to the Rocky Mountains and are a common and popular choice of Christmas tree.
Identification
Leaves: Needle-like, waxy and have a silvery-blue appearance. These needles grow radially on stems that point upwards and are very sharp and prickly. They have a blue-silver, glaucous appearance due to a white powder that forms on the needles from a young age. Blue Spruce needles also have a strong pine scent.
Buds: Yellow-brown and broadly conical. They are resin-less.
Bark: Grey-brown, scaly and patchy.
Form: Dense and pyramidal. Can reach heights of 15+metres.
Reproduction:
Blue Spruces are monoecious meaning that they have both male and female flowers dispersed on a single tree. The female flowers are greeny-purple, and the male flowers are an orangey-yellow. Once pollinated, oblong and ovate cones form and are brown and dry once matured, with papery scales. Once fully ripened, small-winged chestnut-brown seeds drop.
Growth Habit:
Slow to medium growth rate yet has a long lifespan (typically between 600-800 years).
Interesting Facts:
The Blue Spruce wasn’t discovered until 1862, where it was found in the Rocky Mountains and is considered to be one of nature’s best-kept secrets.
Ecological Importance:
Blue Spruces provide great nesting sites for birds as well as providing food and shelter to siskins, nuthatches and crossbills.
Properties of Blue Spruce Wood and its Uses:
Blue Sprucewood is fast-burning firewood, making it good to use for kindling. It was also once used for building materials, and the native Americans used the tree as a medicinal plant. Additionally, the boughs of the tree are still commonly used as craft materials.
Styling of Blue Spruce/Where to Find Them:
Blue Spruces are great ornamental, specimen and parks and gardens. They also make great Christmas trees for those who want something a bit different at Christmas.
Associated Pests and Diseases:
Blue Spruces are susceptible to a range of pests including two species of adelgids; the nymphs of Pineapple Gall Adelgids and Spruce Gall Adelgids; spruce budworms, white scale insects, pine needle scale and spruce beetle. They are also susceptible to several needle casting diseases such as Rhizosphaera needle cast, cytospora canker and Lirula needle blight.
Maintenance
Pruning and Pruning Qualities: It is not necessary or a requirement to prune a Blue Spruce. However, pruning can encourage a denser foliage to form. If you do decide to prune your Blue Spruce, then this should be carried out in spring. Also, it is worth consulting your local tree surgeon as they will be able to advise you on any work you need carrying out or if you have queries. You can find your local tree surgeon, here.
Growth Rate after Pruning: Pruning can help encourage a denser foliage.
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