The pines are some of our most picturesque trees, both in the landscape and in gardens whilst among the many species and varieties in this genus are some to fit every purpose. Once again many of the varieties have to be propagated by grafting and so will not be so readily available as seedling raised plants or those which come from cuttings. They are also likely to be more expensive. Most are easy to grow, many succeeding on very poor dry soils where other conifers would fail. Some species are used for forestry purposes and among these is one of our three British native conifers, Pinus sylvestris, the Scots pine. All pines have needle-like foliage and most species grow cones when well established which vary somewhat in size, shape and attractiveness.
P. cembra to my mind should be grown more widely than at present. Its common name is the Swiss stone pine and it makes a broad conical-shaped tree in time, retaining its bottom branches even as a mature specimen. The dark blue-green foliage only changes each spring when distinctive orange-brown shoots appear to herald another season’s growth. Slow growing during its first few years, it may only be 6 to 7 ft. at the ten-year stage but eventually reaches 30 to 40 ft.
P. densiflora, the Japanese red pine, is somewhat similar to the Scots pine, P. sylvestris, but although it is not often used in the British Isles it has given us a few useful dwarf forms, the most notable of which is P. d. umbraculifera. This unwieldy name when translated from latin means umbrella and this is indeed somewhat descriptive of the habit of a mature specimen of this plant. It has long dark green leaves which turn somewhat bronzed in winter. At ten years old it will be 3 to 4 ft. and ultimately perhaps 10 to 12 ft. high with almost a similar spread.
Although again perhaps too rapid growing for all but the largest gardens P. griffithii, or P. wallichiana as it should be now known, is such a beautiful tree that I feel it should be included in this section. It originated from the Himalayan Mountains and is commonly known as the Bhutan pine. It has long bluish-green needles and a very graceful broadly conical habit. Reaching 15 ft. in ten years, it will grow to well over 100 ft. at maturity.
P. mugo, the mountain pine, grows wild all over the mountains of central Europe, varying considerably in habit and rate of growth and as a garden plant can be expected to make a medium to large shrub. It is therefore somewhat difficult to give any more explicit indications as to rates of growth. Nonetheless it can make a most attractive garden plant but if a more regulated form is required the variety Gnom is worth looking for. This is of course grafted and can be expected to grow 2 to 3 ft. high and spread about the same in its first ten years, eventually reaching a height and spread of 5 to 6 ft.
P. nigra, the Austrian pine, offers an alternative to the Scots pine for use as a windbreak and screen. It has dark green foliage, a colour held throughout the year, is hardy and adaptable to most soil conditions. It is conical when young but loses its bottom branches with age becoming more mop headed or flat topped. Eventually growing to 60 to 100 ft., it will at ten years reach 6 to 10 ft. so could not really be considered for the small garden. It has produced some useful dwarf forms.
P. parvifiora, the Japanese white pine, is an attractive species which is not grown widely in the British Isles at present. It has light bluish-green leaves and cones of greenish blue until they ripen. There is a selected form which is one of the most beautiful slow-growing pines, P. p. glauca. It has a narrower and more ascending habit than the species with distinctively blue leaves. Both have similar rates of growth reaching 6 to 8 ft. in ten years and eventually 20 to 30 ft.
P. sylvestris is a familiar sight on the British landscape with its craggy appearance as a mature specimen. The Scots pine varies as do most species in habit and rate of growth but it normally makes a medium to large tree. Conical when young it becomes mop headed or flat topped with age losing its lower branches in the process. The foliage is blue green, the bark reddish when it becomes exposed. At ten years it will grow 10 to 15 ft. and at maturity anything from 45 to 100 ft. It has given us some useful garden forms not least of which is the golden Scots pine, P. s. aurea, which is similar to the species in all respects except that the leaves turn a wonderful yellow during the winter months — a real bonus! It will grow 4 to 5 ft. in ten years and eventually maybe 15 to 20 ft.
One of the dwarfest pines is P. s. beuvronensis which makes a dense blue-green bush wider than high. Like all plants and particularly dwarf conifers if grown on poor soil or with a restricted root run, it will be much dwarfer than if given extremely fertile conditions. With age it may become more vigorous than my growth estimates suggest, but at any rate it is a first-class garden plant. After ten years it may have made 2 to 3 ft. in height and spread, ultimately 4 to 5 ft. in height and spreading as much as 8 to 10 ft.
Many other dwarf and slow-growing forms of P. sylvestris are in existence but not many will be readily available in nurserymen’s catalogues at present. On that sad note we leave the pines.