The spruces have given us a multitude of good garden varieties, although many are not generally available except from specialist nurseries. This is primarily because many varieties have to be grafted which is a specialist propagation procedure. Many fine varieties are likely to become widely known when supplies become more readily available, but in the meantime prices are likely to be high and some searching through specialist catalogues will be necessary to track down some of the most desirable forms.
Picea abies is known more commonly as the Norway spruce or even more commonly as the Christmas tree in the British Isles. The species is used only as a forest tree and is not recommended as a garden conifer even though it may look attractive in its early years.
Some confusion exists with the naming of many of the dwarf forms but ‘ here follows a selection of some of the most distinctive.
P. a. gregoryana makes a very slow-growing hummock of tight dark green foliage which is prickly to the touch. Most of the abies varieties have brownish resinous winter buds which add to their attractiveness. After ten years gregoryana will make a cushion-shaped plant about 6 to 8 in. high and will ultimately only reach 18 to 20 in. in height but spreading perhaps 3 to 4 ft.
P. a. nidiformis is a most attractive dwarf spruce for any garden. It has a flat-topped and spreading habit, dark green with typical brown resinous winter buds which open in spring to produce the bright green shoots for the next season’s growth. From 12 to 15 in. high by perhaps 2 ft. in width after ten years it will grow eventually as high as 3 to 6 ft. and spread 8 to 9 ft. A variety with a more upright habit is ohlendorffii. It has the same dark green foliage as the previous variety and dark orange-brown winter buds.
P. breweriana must be classed as one of the most beautiful of all conifers — but it takes many years in most situations to attain this stature. Broadly conical in habit it has long pendulous branches with dark blue-green foliage. It prefers a situation of some shelter and even slight shade but enjoys plenty of moisture. Although eventually becoming a large tree it will probably only grow 4 to 5 ft. in its first ten years and after a great many more attain possibly 45 to 50 ft.
One of the most popular and widely grown spruces is P. glauca albertiana conica. It is very hardy and not difficult to grow, a splendid garden plant, making a perfect cone-shaped specimen. The foliage is dark green except for the period in spring and early summer when its new growth gives it a bright emerald-green colour. This plant should in my opinion be in every garden although one has to admit it does seem to get attacked by its fair share of pests such as red spider mite. However, these can be controlled quite easily by spraying with a systemic insecticide once or twice through the summer months. After ten years it will grow to about 4 ft. and at maturity maybe as much as 10 to 12 ft.
P. omorika, the Serbian spruce, is once again rather too large for all except the largest of gardens, but is one of the most trouble-free conifers and certainly one of the most attractive of spruces. With its narrow pyramidal habit and leaves of dark green, it associates well with silver birch and makes an excellent screening or accent plant with its stately bearing. Reaching 8 to loft, at ten years of age, it will eventually grow to 60 to 75 ft.
P. pungens has given us some of the most exciting silver and blue varieties of any genus — but all named forms need to be propagated by grafting — hence the scarcity of these in general circulation. Selections of seedlings from the species P. pungens are often made and these forms will generally be listed as P. p. glauca and can of course vary considerably. A selected dwarf form of great merit is P. p. globosa which makes a dense bush of silver blue. It is a beautiful foliage form and particularly useful for the small garden, growing in ten years perhaps 2 ft. high and eventually 4 to 5 ft. with a similar spread.
Of the upright and larger-growing forms there is quite a wide selection but any of them could be considered worth having. Perhaps the most widely available is Koster. This has a pyramidal shape but like all the grafted forms it may take a year or two of training the leading shoot in a vertical position before it decides to grow that way on its own account. It is a silver blue the year round but the colour is particularly pronounced in the early summer when new shoots appear. Growing 6 to 8 ft. in ten years, it will eventually reach 20 to 30 ft. Normally these P. pungens varieties have no particular fads or fancies but they prefer an open position. Other varieties of merit are spekii and moer heimii and there are many more as yet almost unobtainable in Britain.