DWARF COLORADO SPRUCES

The Colorado blue spruce, Picea pungens, has a number of cultivars that are classified as dwarf. Unfortunately most fit a very loose definition of the word dwarf and are suitable for only temporary roles in the landscape as dwarf plants. The collector, the landscape designer, the homeowner, and the nurseryman each has different concerns and attitudes about this cultivar group.

The collector wants every plant in his collection to have a correct name. The landscape designer must know the correct name and description of every plant utilized in a landscape project. The homeowner wants a plant to grow as it was represented. The nurseryman wants to sell plants that are true to name so that all of his customers receive what they pay for.

A true dwarf with commercial value, Picea pungens ‘St. Mary’ is difficult to find in the retail market. Taking twenty years to reach a height of 30 inches with a spread of 4 feet across the base, ‘St. Mary, is a most desirable plant, but one that must command a higher price due to its slower growth rate. It will never be a "bread and butter" item, but a number of the better nurseries are starting to grow it. It does have one definite drawback. If it is grown in the ground for the B&B trade, ‘St. Mary’ has a tendency to be "floppy" in the ball when dug, possibly due to the bottom branches lying on the ground, preventing movement in the wind. ‘Saint Mary’ was discovered as a witches’ -broom. At this writing, the original broom is still alive in New Jersey.

Many of the cultivars of Picea pungens found throughout the nursery trade which are sold as dwarf blue spruce could be more correctly sold as compact forms. They include the cultivars ‘Compacta’ (no longer in cultivation), ‘Glauca Compacta’, ‘Glauca Globosa’, ‘Hunnewelliana’, ‘R.H. Montgomery’, and ‘Thuem’. All rapidly develop into mature plants and are very difficult to distinguish from each other when young.

The true Picea pungens ‘Compacta’ is green and lost to the trade. A number of years ago I saw it at the Arnold Arboretum - about 10 feet tall with a few green branches at its top. On my last visit to the arboretum it was gone. This cultivar originally grew from seed collected in 1863 at Pike’s Peak, Colorado. Thirty-four years later, in 1897, the original plant was 3 feet tall. It is the oldest form of Picea pungens to be recorded and may be of historical interest to conifer collectors.

A number of compact forms that have turned up in seed beds have been selected and put on the market with "compacta" and "glauca" often appearing in the name. In America, Picea pungens ‘Thuem’ has been widely distributed as ‘Glauca Compacta’. Not a dwarf form, it grows with a compact habit and good blue color. Its growth rate is slower than ‘Hunnewelliana’ but faster than ‘R.H. Montgomery’. A specimen of ‘Thuem’ is at the Oliver Nursery in Connecticut. It was given to John Oliver by Mr. Thuem. Grafted plants offered by Coenosium Gardens can be traced to this plant.

I have propagated a plant from Layne Ziegenfuss that is believed to have come from England as Picea pungens ‘Glauca Compacta’. It is unlike any of the compact forms now available in this country. Its needles are bright blue and very sharply pointed. It grows faster than ‘R.H. Montgomery’ but with a finer texture and needles.

Colonel Robert H. Montgomery was an avid conifer collector with a world class collection at his 100 acre estate, "Wild Acres", near Cos Cob, Connecticut. In 1947 he donated the conifer collection to the New York Botanic Garden, where it can still be seen today. In 1949 the collection was dedicated and at that time Picea pungens ‘R.H. Montgomery’ was formally named. The American Conifer Society Bulletin of Winter, 1985 has a profile of Colonel Montgomery’s life. After a slow start following its naming, ‘R.H. Montgomery’ has become "the dwarf blue spruce" in America. It is a conical plant that can grow as much as 9 inches per year. If its leader is removed, the plant will then grow wider than high, until developing a new leader.

A number of years after the introduction of ‘R. H. Montgomery’ a "new" dwarf blue spruce appeared in America. Introduced by the Dutch as Picea pungens ‘Glauca Globosa’, it soon became a very popular plant in the nursery trade. Unfortunately its origin is shrouded in some mystery. Supposedly ‘Glauca Globosa’ originated as a seedling at a Dutch Nursery in 1935. However, no one can trace it to a particular nursery, since the original plant had never been recorded. It appeared in the nursery trade in Holland after ‘R.H. Montgomery’ was named, and Layne Ziegenfuss found a specimen of ‘Glauca Globosa’ in a private estate that was accessioned in 1934. A core sample of the trunk verified that date. Today that plant would be 30 to 35 feet tall. Picea pungens ‘Glauca Globosa’ is indistinguishable from ‘R.H. Montgomery’ in growth habit. I have been told that the difference between the two is in the number of bud scales of a mature bud.

To add to the confusion, propagated wood from two different areas of a specimen of ‘R.H. Montgomery’ will often produce two different groups of plants with distinctly different foliages.

Whether or not a nursery is actually growing ‘Glauca Globosa’ or ‘R.H. Montgomery’ is a moot point since for all intents and purposes there is no difference to the consumer. Propagation of terminals will tend to produce ‘R.H. Montgomery’ while laterals will tend to produce ‘Glanca Globosa’. Enhance the desired effect with careful pruning and the nursery has whichever form it wants ("Poppycock!" says the conifer taxonomist.) The taxonomist is bound "to get bent out of shape" over such a statement, but the nurseryman has to take a more "practical" attitude. There evidently is a ‘Glauca Globosa’ in a collection somewhere, but the nurseryman wants a cultivariant under this name, not necessarily the actual plant. Those of us "in the know" must consider any ‘Glauca Globosa’ as a cultivariant unless the plant can be certified as possessing some characteristic other than growth habit or foliage that distinguishes it from ‘R.H. Montgomery’, and that characteristic has to be traceable back to the oldest labeled ‘Glauca Globosa’ that can be located.

Another plant that has been gaining popularity is Picea pungens ‘Hunnewelliana’. The plant being produced under this name is not the actual plant first given this name. The original plant ‘Hunnewelliana’ was green, compact, and located at the Walter Hunnewell Estate. This green plant is the one described in conifer books. (The taxonomy of conifer cultivars is confused in several noteworthy cases, and this case is one of them.) The confusion in this particular instance may have been caused by a labeling mixup at a time of propagation. Early in the 1900’s, conifers at the Hunnewell Estate were propagated by people from the Arnold Arboretum for their collections. One of these plants was the green ‘Hunnewelliana’. Another plant may have been a specimen labeled as Picea pungens ‘Glauca Compacta’, observed at the Hunnewell Estate a number of years ago. The green ‘Hunnewelliana’ may still be thriving at the estate while the ‘Glanca Compacta’ has probably been choked out by surrounding brush and trees.

At the Arnold Arboretum the blue plant developed into an attractive specimen while the green plant did not appear to be anything special. Eventually the green tree was removed while the blue one was retained. This tree is the one accessioned as Picea pungens ‘Hunnewelliana’. It is a distinctive plant unlike any of the other compact Picea pungens cultivars presently in cultivation. It is the fastest growing of the "dwarf blue spruces". It develops into a narrow, pyramidal tree with a powder blue color similar to that of ‘R.H. Montgomery’.

A number of other dwarf cultivars of Picea pungens are increasing in popularity and need to be mentioned at this time. Among the dwarf selections are several that originated at Iseli Nursery when my good friend Jean Iseli was the "Head Grunt" (as he referred to himself). My favorite is Picea pungens ‘Donna’s Rainbow’. It is a dwarf, roundly conical selection with an almost foxtail like appearance to its branches and a very soft bark on the recent year’s growth. I have six small specimens in my collection and they are all very distinctive and very slow growing, about 2" per year. Another selection, ‘Yvette’ is very dwarf and very hard to propagate. It is a cushion-shaped plant that grows about 1" per year and is very similar to a Dick Bush plant named ‘Porcupine’.

Picea pungens ‘Jean Iseli’ was found by the late Edsal Wood and named for Jean. When rooted, it is a dwarf, flat-topped bush with a depressed center and small, thin needles. Since it roots easily, some think it may not be a Picea pungens at all. However, grafted plants take on an upright growth habit with coarse textured, Picea pungens foliage and an irregular outline.

An old cultivar named Picea pungens ‘Moll’ is a dwarf, conical selection with good color that is densely branched and grows about 2" per year. It develops at about the same rate as ‘Donna’s Rainbow’ with a similar shape, but it will have a more symmetrical outline.

Picea pungens ‘Gloria’ is a plant that originated in England and is similar to ‘Saint Mary’ in shape and growth rate. It does not seem to have the tendency to develop dead terminal buds that afflicts ‘Saint Mary’ and thus does grow with a bit more open branch structure.

Picea pungens ‘Corbet’ is a dwarf, conical plant with a dense branch structure and relatively short, blue needles that stand straight out from the branches. It grows up to 4" per year, and its foliage makes it actually quite distinctive.

Picea pungens ‘Green Globe’ is very dwarf and fits its name for up to six years. Then it gradually becomes squatly conical. This plant was evidently given a descriptive name before it developed a mature character. The foliage is dark green, and the plant is very attractive in the landscape.

Picea pungens ‘Blue Pearl’ is a dense, globose selection with good blue foliage and needles that are thinner than those of ‘Saint Mary’. It grows at about the same rate as ‘Saint Mary’ but is not as cushion-shaped. It was discovered as a witches-broom on ‘Fat Albert’ at Iseli Nursery.

Picea pungens ‘Mrs. Cessarini’ is a confusing plant. It is a dense, flat topped bush with coarse blue and green foliage. The founder, Joe Cessarini discovered it as a witches’-broom and maintains that it was found on a Picea abies. The foliage is uncharacteristic to either species so he could be right. However, a graft of this cultivar was made onto the top of a twenty foot high Picea abies f. pendula by Eddie Rezek and it was pushed very hard into very rapid growth. It looks very much like Picea pungens ‘R.H. Montgomery’ in this particular instance. For that reason I have labeled it as Picea pungens.

One of the more exciting cultivars from this group is a selection from Australia named Picea pungens ‘Early Cones’. It is a dwarf, flat topped bush with thin branches and fine textured foliage. Its most striking characteristic is the development of miniature cones on the tips of the recent year’s growth. A mature plant makes a striking addition to the smaller garden.

There is another whole group of cultivars and cultivariants of Picea pungens that have drooping or prostrate branches. Following are a few of them.

Picea pungens ‘Kleinood Luusborg’, which I have only observed at Trompenburg Arboretum, is a spreading bush that only gains height by developing additional tiers. It does not develop a leader and looks a little like Picea abies ‘Tabuliformis’ with Picea pungens foliage. It is an intermediary between dwarf and prostrate selections of Picea pungens.

Picea pungens ‘Glauca Pendula’ is a tree that meanders its way upward with the leader often knuckling back over. Its blue foliage and the drooping branches make this plant a natural for the informal landscape. Unfortunately this plant can be very hard to find as it takes many years to develop a mature outline, and most nurseries won’t take the time to develop such a plant.

Picea pungens ‘Koster Pendula’ tends to be more upright with side branches that are quite pendulous. This particular plant may be the actual ‘Glauca Pendula’ that was originally introduced by the Koster Nursery in Germany. Although it differs from the cultivar presently offered as ‘Glauca Pendula’, one or the other may be a variation that developed from the propagation of lateral shoots. 

The selection Picea pungens ‘The Blues’ was a selection from Picea pungens ‘Glauca Pendula’ and is more strongly pendulous than any of the other forms presently in the trade.

The flat growing selections are grouped together by Humphrey Welch into a category he created- cultivariants. Picea pungens ‘Glauca Prostrata’ is a side graft that starts out flat but eventually grows into an upright tree. 

Picea pungens ‘Glauca Procumbens’ seems to be more reliable but will often revert to an upright form. Judicious pruning can keep this plant under control and help it remain a most interesting ground cover.

Picea pungens ‘Pendens’, growing at the Arnold Arboretum, created a nice effect as it cascaded over a wall. It too developed a leader that had to be removed and has a strong resemblance to ‘Procumbens’.

I have only described a few of the special forms of Picea pungens that are available at specialty nurseries. There are many I have not described: the full sized cultivars and an assortment of dwarf selections from witches’-brooms that are under evaluation. I am sure that many of these cultivars will appear in future articles.

Picea pungens has produced many excellent cultivars, and almost every landscape in a temperate climate can benefit from the presence of one or more of them.

Counter Started December 1, 2001