Spruce - Abies Concolor

Spruce - Abies Concolor

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The Abies concolor fir is an evergreen conifer, native to North America; it is a fairly slow-growing tree, medium long-lived, which can reach 15-25 meters in height, and 3-8 meters in width. The young specimens have the classic conical crown, with age this fir takes on a more elongated shape, like a candle. The stem is erect, and has horizontal branches, only the branches near the ground tend slightly downwards; the foliage consists of needles, 4-7 cm long, bluish-green in color, often facing upwards. In spring it produces female and male inflorescences, of different color, followed by woody pine cones, which fall from the tree in autumn, releasing the seeds. Tree very suitable as a single specimen, it needs a lot of space to develop at its best; there are some cultivars with intensely colored needles.

Characteristics of the Colorado Spruce

The Colorado spruce, also known as silver or silver fir, is a conifer native to the western United States. Its natural habitat in particular is represented by the slopes of the Rocky Mountains. In its spontaneous state it can even reach 40 meters in height and generally takes on a narrow cone shape over time, with a diameter usually not exceeding 150 cm.
In old trees an important feature is the absence of branches in the lower part of the trunk. Often this is free of branches from 1/3 to Ѕ of its height.

Family and gender
Pinaceae, abies concolor
Type of plant Evergreen tree
Exposure Sun, partial shade, moderate shade
Rustic Very rustic
Ground Deep, from subacid to acid, moist, well drained
colors Foliage from green to silvery to glaucous
Height Up to 40 meters
Purposes Christmas tree, isolated specimen, thickets, barrier

The leaves are linear, up to 6 cm long, with a blunt apex. In the upper branches the needles tend to be smaller and bent than those in the lower branches. The color ranges from blue gray to green gray (in the species they are glaucous in juvenile and then turn green) equal on both sides of the leaf (hence the name of the species). The bark is smooth, but with age it becomes scaly, of a beautiful light ash gray with numerous ravines from which some resin comes out. In old individuals, color can turn red-brown. The male flowers are yellow, at the base of the branch, the female ones instead are yellow-green, erect. Both are collected in bunches, however separated, on the same plant and spring up in the spring. The fruits have a cylindrical cone, erect, up to 10 cm long. Initially they are green and purple, then the color turns brown.
Pollination takes place at the end of spring, mainly due to wind, and the maturation of the cone occurs by the end of the same year. They are in fact ready in the middle of autumn, when they fall and tend to break into many pieces when the seeds are dispersed.
The abies concolor grows even in particularly unfavorable conditions from the point of view of exposure. It tolerates the shadow very well and grows optimally when the soil is particularly silty, but it can also be found where there are poor and dry soils.
The species rarely creates pure populations, indeed, most of the times it grows in association with numerous other essences, depending on its location and altitude. It usually creates populations with Douglas fir, pinus lambertiana, yellow pine and spruce.

Places of origin

The areas in which this conifer is endemic are really large. It is found quite easily from the Rocky Mountains of Colorado and New Mexico to the heights of California and Oregon. The ideal altitude goes from 1800 meters to 3500, but near the coasts it can also be found at 700 meters above sea level. The differences between the two habitats and the consequent morphological differences had led some botanists to propose separation in two different taxonomic classes, but the project did not find the approval of the whole scientific community.


The Colorado spruce grows easily in areas characterized by a moderately humid climate with long winters, but slightly precipitations and snow deposits. It is mainly found where rainfall is over 50 cm, even if it develops ideally only in areas where annual rainfall ranges from 90 to 180 cm. For this the area in which it is most common is the Sierra Nevada above 2000 meters above sea level.
It is a plant that tolerates a large number of different soils well. It can therefore be found where there is andesite, basalt, granite, pumice, quartz or even other types of sedimentary rock.
Deep and permeable soils are the best for its growth, especially if an adequate amount of humus is incorporated. Usually they are composed of moderately to strongly acid, friable, granular or slimy. These conditions are found primarily throughout the western United States.


prefers sunny, or semi-shady places; it does not fear the cold. In areas with very hot summers it is advisable to place the Abete plant in the shade to avoid excessive heat. This tree tolerates heat quite well, in any case better than many other fir trees.


the fir tree is generally satisfied with the rains; can withstand periods of drought, even prolonged.


it is cultivated in fertile and deep, very well drained soil. It is not advisable to place the fir in places that have shallow ground, near basements or house foundations, since the root system of a large tree can be very invasive.

Multiplication and propagation

It occurs by seed, in spring; before sowing it is advisable to place the small seeds in the refrigerator for at least 4-6 weeks.
Propagation in nature generally takes place via seed, while at the nursery level the cutting and grafting are more practiced. Generally the latter are preferred both because they allow to have adult specimens in a shorter time and because it is the only method that guarantees the preservation of the original characters of some cultivars.
The repopulation of an area can be obtained by self-dissemination, by direct seeding of the man or by inserting small specimens.
The cones begin to open and decompose from the end of September to the beginning of October. most of the time for a single tree there are vintages with large production and others more scarce, with an alternation of 2 or 5 years.
The seeds give rise to weeping in the spring, but the germination is rather low, around 50%. To obtain good results, therefore, it is advisable to put at least 15 pine nuts at a time.
Fortunately, as we have said, the abies concolor tolerates the shadow very well and therefore, even if initially disadvantaged due to this low germination ability, it manages to develop its own plants well until they reach the height suitable for exposing them to sunlight and dominate the environment.
The growth initially, for the first 30 years, is quite slow. Once that age is reached, it grows exponentially.
The ideal specimens for planting are those with an age of 2 to 4 years.

Pests and diseases abies concolor

He may be struck by the cedar aphid and the processionary. In our country they are generally rather autonomous plants that do not require constant maintenance and are rarely attacked by insects.
It may happen that some moths reproduce there, or that the bark becomes an ideal habitat for various types of beetles. It is rarely the case to intervene with specific products.
Instead, the possible incidence of radical rots caused, in most cases, by a not ideal planting should be taken more seriously. It is always good, in fact, to create, especially where the soil is heavy, a good draining layer on the bottom of the hole. The drainage of the water guarantees the optimal degree of humidity to the hypogeum apparatus avoiding the onset of fungal attacks, almost impossible then to be eradicated.
Another rather serious problem, especially for specimens kept in the house for too long (as it happens for Christmas trees) and for those inserted in areas that are too hot and humid, is rust. It is better to avoid the use of sulfur-based products for prevention because the abies concolor is very sensitive and large burns may occur.
If the area in which we live is compatible with this problem, we rather use synthetic products that have been tested on delicate vegetables like this.


The Colorado spruce is also very popular in cultivation, both in forestry and as an ornamental tree.
It was initially used in all the eastern United States and Canada both in gardens and as a cemetery conifer, thanks to its color that creates a nice contrast with the other evergreens. Thanks to this feature, it has also spread to the rest of the world, particularly in Europe and South-East Asia, more or less in the same areas.
He also started planting it in gardens or selling it in pots during the Christmas season as it is very suitable to be decorated for this holiday. One of its important characteristics, in addition to the beautiful coloring and the scent it gives off, is not to lose the needles even when it is cut. It is therefore ideal to keep at home (for a short period) or to make decorations or garlands.

Wood and other uses in industry

Colorado fir wood is light, soft and coarse-grained.
Its first use was for the production of cellulose for paper, then the wood was also used for the construction of crates and packaging.
Since it is characterized by the almost total absence of perfume, it was used to make tubs for storing butter.
From its leaves a useful essence is extracted for the production of balsamic oils and medicines, used for the treatment of respiratory diseases and for relaxing massages.

Ecological importance

The Colorado spruce is of fundamental importance for a large number of wild species. Deer and fallow deer feed on its buds and leaves during winter, porcupines eat its bark, squirrels and other rodents feed on seeds. Pheasants and other birds eagerly seek pine nuts when they have already escaped from the cones.


Some cultivars are available. The most known are:
Compacta or compact dwarf, suitable for medium-sized gardens
pyramidalis with a more conical bearing
Blue Cloak "Blue Globe ',' Blue Select ',' Candicans', 'Dwarf Blue', 'Gables eeping', 'Glenmore",' Sherwood Blue ',' Winter Gold, "purplish": different leaf colors.

Use in the garden

The Colorado spruce can be used in different ways to decorate our green space.
First of all it can be a great tree for building barriers. On the contrary, it can be used in a focal point as an isolated specimen or for the creation of small woods in association with other conifers or evergreens.
However, we keep in mind that over the years they will become specimens of great size. If this is not what we are looking for, let us turn our attention to another essence (or to a compact cultivar). The opportunity to proceed with pruning is not to be taken into consideration. It would do nothing but damage it as well as defraud it of its natural form, the only one that can really be called decorative.
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