On this site we are going to explore a wide variety of plants and trees, and today we would like to introduce you to what is scientifically known as spruce pungens, a conifer common in the United States whose common name is blue spruce or Colorado spruce. This tree species is native to the mountains of western North America and is widely grown around the world for its attractive blue-gray color and well-defined conical shape.
spruce pungens It is a monoecious tree with slow growth, but which can reach up to 30 meters in height at maturity. It is a long-lived tree, surviving up to 600 years or more, and a popular choice for gardens and landscapes due to its drought and frost tolerance, as well as its ability to withstand harsh weather conditions. common pests and diseases.
Contents
Characteristics of spruce pungens
Blue spruce is an evergreen conifer that growing slowly until reaching an average height of 50 m and a trunk thickness of 1.5 m in diameter. Some of the main features of each of its parts are:
- Aspect: It has a conical shape, very common in most species of conifers.
- Cortex: grayish brown.
- branches: grow with a decreasing angle, aligned downwards. Robust appearance, soft wood and yellow-brown color, generally glabrous.
- Leaves: they are needle-shaped, 1.6-3 cm long, rigid, blue-green in color and with a thorn-like top.
- seed cones They are born in the upper crown of the tree. Pale green or red when fresh, maturing to pale beige-brown, 5–12 cm long, with elliptical or diamond-shaped scales, wider below the middle. Seed cones ripen in August.
taxonomic classification
| Order | Pinals |
| Family | pinaceae |
| Gender | Spruce |
| Species | Spruce quills |
Common names: Colorado Blue Spruce, Blue Spruce, Silver Fir and King Pine.
The species name describes the exceptionally prickly needles of this conifer. It is the state tree of Colorado. The initial growth of blue spruce seedlings is very slow, developing around 15-16 cm 2 years after germination. Blue spruce is valued primarily for its appearance. At least 38 blue spruce cultivars have been named, primarily for leaf coloration and crown shape.
Some of them are:
| ‘Argentea’ rosenthal | silver white |
| ‘Golden’ Niemitz | golden yellow |
| ‘Bakery’ Bailey | Intense bluish white, long leaf. |
| ‘Caerulea’ Beissner | Bluish white |
| rehder ‘compact’ | Dwarf, compact, densely flat on top |
| ‘creepy’ Beissner | Bluish green; collective name for all cultivars with glaucous leaves |
| ‘Glauca Pendulum’ Koster ex-Beissner | Dangling leaves, bluish, strongly sickle-shaped. |
| ‘Hoopsii’ earrings ex FJ Grootend | Dense, pyramidal; very silvery leaves |
| “Hunnewellian” Hornibr. | Dwarf, dense, pyramidal; pale green leaves |
| Boom ‘Kost’ | Pyramidal, branched pendulous, with the main branches almost horizontal; bluish white to silvery white leaves |
| Ruyes ‘Moerheimi’ | pyramidal, slender, dense, compact; dark blue leaves |
| ‘Thomas’ thomson | Pyramidal; whitish to silvery-blue leaves, long |
| Freeze ‘Virides’ | dull green |
grow guide spruce pungens
Weather situation
spruce pungens prefers to grow in conditions cool and humid weather in summer, with minimum winter temperatures of -10°C and maximum summer temperatures of 20-22°C. Blue spruce seedlings are more sensitive to daytime temperatures (13°C to 31°C) than to nighttime temperatures (7°C to 25°C).
It also resists very well to low temperatures and strong insolation compared to other conifers of the genus.
the type of soil
The characteristics of the soil are not a determining factor for the cultivation of blue spruce, since many of the American soils where it grows natively are young and there is great diversity depending on the state where we are. Preferably, it prefers loose, fertile, cool soils that offer good moisture retention.
He optimum pH for this conifer it is 6.8 to 7.2, practically neutral.
Watering and humidity
Under natural conditions, its ideal zone receives an average rainfall of between 400 and 600 mm per year. It is one of the most drought-tolerant coniferous species of the genus Picea.
Grown in the garden, a drip irrigation system is usually placed, where in winter we will practically not supply water if the average rainfall is similar to the values mentioned above. In summer, especially if we have grown our spruce pungens in a slightly warmer environment, we will water 2 to 3 times a week, between 30 and 40 minutes.
Multiplication of blue spruce
Multiplication usually occurs by seeds. Blue spruce is generally considered to produce a large number of good quality seeds. emitting cones every 2 or 3 years. Seed production begins around 20 years and the optimum age is reached between 50 and 150 years.. Natural vegetative reproduction of blue spruce has not been reported, but successfully multiplication by grafting (rooting of hardwood cuttings or green stems, especially in sand, peat and soil).
Cones ripen in August and seed molting begins in early to late September, depending on elevation, and continues through winter. There the seed is spread by the wind. If one year produces very good quality seed, the next year it is likely to lose quality, and so on.
blue spruce seeds germinate in a wide variety of media, although natural reproduction is limited to slightly moist, shady soils. However, natural reproduction is poor, probably because the lightweight seed cannot contact mineral soil due to dense undergrowth, grass, or other vegetation. However, if we bring the seed to a substrate, it has great germinative power.
the seeds of spruce pungens they germinate quickly and completely without prior stratification, under a wide range of temperatures, with or without light. Natural seed germination takes place in spring or summer.
Pests and diseases that affect this conifer
Various insects are classified attacking the cones and seeds of spruce pungens during its growth, but the damage caused by insects is not particularly serious. Here are some examples of insects that attack this conifer:
- fir seed calcide (Megastigmus piceae)
- Spruce moth larvae (Laspeyresia youngana)
- cochylid cone (Henricus fuscodorsana)
- Spruce tree moth larvae (Dioryctria reniculelloides)
- fir needle miner (Abolin Taniva)
- Cooley spruce aphid (Adelges cooleyi) and pine aphids (Pineus pinifoliae And Pineus similis)
- Beetles (Pityophthora spp) and the spruce beetle (Dendroctonus rufipennis)
- Root nematodes (Pratylenchus penetrans)
With respect to diseases that affect spruce pungens:
- Rust (Chrysomyxa pirolata): infects pineapples, although seed production is not greatly affected by this disease
- Damping off caused by Phytophthora cinnamomi
- root rot (Cylindrocladium scoparius)
- cankers (Leukocytospora kunzei)
- western spruce dwarf mistletoe (Arceuthobium microcarpum)
Other conifers of interest
All our articles on conifers.
Source of information: srs.fs.usda.gov
Cover photo: Quinn Dombrowski from Chicago, USA – Bryce Canyon National Park.