Perhaps the worst of all the uses to which Conifers have been put is that of forming long avenues across parks. It is difficult to understand the frame of mind that would prefer rows of Araucaria, Abies nobilis, or other similar things—however well grown and pyramidal they might be—to a noble vista of Chestnut, Oak, or Lime, with its canopy of branch and foliage overhead. Conifers can, however, be used effectively for forming short avenues within the garden itself, especially in the more trimly-kept parts.
The practice that is frequently adopted of forming a pinetum and bringing together the members of this family in one part of the grounds is a very good one. It is far better than sprinkling them indiscriminately over the whole garden. At the same time, where sufficient space is not available for the formation of a pinetum they may be used in their proper proportion with other evergreens in various parts of the garden. Single specimens on lawns of Abies, Picea, and of many other genera are always effective, and nothing in the whole range of native or foreign trees is more stately and picturesque than the Cedar of Lebanon. How much do we of the present day owe to those who a century or more ago planted this tree so abundantly in this country!
Before planting Conifers largely in any garden where they are to be grown for their purely ornamental qualities, a study should be made of the species planted in other gardens where the conditions as to soil, moisture, and altitude are similar. On the peaty formations in Surrey and Hampshire where Rhododendrons succeed so well, many Conifers thrive exceedingly well also. The Common Spruce and its allies are nearly all failures on light dry soil, especially where the subsoil is gravel. In places, however, where the Spruces fail, the Common Larch and the Lawson Cypress succeed well. In chalk districts many Conifers refuse to grow, but the following are among those that thrive: Abies magnifica, A. nobilis, A. nordmanniana, and A. Pinsapo, the Cedars, Cupressus lawsoniana, C. macrocarpa, and C. nootkatensis, the Maidenhair tree, the Junipers, the Thuyas, the Yews, and the following Pines: Pinus Laricio and P. austriaca, the Scotch Pine, P. excelsa, and P. Pinaster. Most of the Pines, too, are happy on gravelly or stony ground.
None of the Silver Firs (Abies) or Spruces (Picea) are good trees for planting at the seaside, unless there is sufficient shelter to break the force of the wind, and even then there are very few that will succeed. The species most suitable for planting where there is a thick outer belt are Abies nobilis, A. concolor, A. nordmanniana, and A. pectinata, the Common Silver Fir. Of the Spruces, Picea nigra and P. alba, the North American Spruces, succeed better than the Norway Spruce, P. excelsa, but these, like the Silver Firs, must have the shelter of a good wind break; Picea pungens, P. pungens glauca, and P. Engelmanni will not succeed in exposed places, even in inland localities, and fail entirely by the sea. There is a difference of opinion about Engelmanni. In some places it seems to stand winds well. The Conifers that will thrive by the sea are very few, and probably not more than half-a-dozen kinds can be trusted. The finest of all is undoubtedly Pinus Pinaster, which is essentially a sea-coast Pine, revelling in storms and sprays. For warmer parts, is the Aleppo Pine (P. halepensis), but is only for southern and warm coasts. P. insignis is somewhat tender, but stands the sea gales fairly well, and P. austriaca, and its relative, P. Laricio, are both excellent, specially for making the first barrier against the winds. The hardy Scotch Pine (P. sylvestris), if planted in large masses, grows well, but does not luxuriate close to the sea, and is especially liable to be browned in foliage by the salt spray.
Besides the Pines, one of the finest of Conifers is the Monterey Cypress (Cupressus macrocarpa), which is hardy everywhere on the coast in these islands; it grows finer than it does in its home on the Pacific coast. It makes a fine front barrier against the wind, especially when mixed with the foregoing Pines. The variety C. lambertiana is also excellent. There are two other Conifers which, though not much planted by the sea-coast, will, we believe, prove reliable; these are Cedrus atlantica and Thuya gigantea (sometimes called T. Lobbii). A third Conifer that we have seen doing well by the sea is Abies Pinsapo, but it must have a temporary shelter in its small state. This subject of seaside planting—the most difficult in a tree planter's practice—is an important one, and it is only possible to treat the matter generally.
The Conifer family is especially noteworthy for the way many of its species vary. Not only is this propensity evidenced in such characters as the colour of the leaf and the differences in habit; it shows itself more remarkably sometimes in the form and texture of the leaf and mode of branching. So great is the difference between some forms of certain species of Conifers that they have been placed in different genera. What are generally known as Retinosporas, for instance, are really nothing more than forms, "states" the botanists term them, assumed by various species of Thuya and Cupressus. Strictly speaking, Retinospora has no separate existence as a genus. This, however, is a botanical phase of the matter. Horticulturally we are more concerned with such variations as adapt the plants to various garden purposes. Many quaint and dainty forms of large trees are very suitable for the rock-garden in association with other alpine plants. The Common Spruce, for instance, has given birth to many pigmy forms. The Yew, the Scotch Pine, and various others have "sported" in a similar way. But no hardy tree varies so much, perhaps, as the Lawson Cypress when raised from seed. The species has assumed almost every shade of colour that Conifers do assume, and every form of growth. Beautiful golden, variegated, pendulous, and erect varieties have been raised, and not only from the Lawson Cypress, but from many other Conifers also. The Golden Yews, the yellow form of the Monterey Cypress, and the golden variety of the Scotch Pine, may be recommended to those who require this colour, although in the Pine it only shows itself in winter. The blue-white or glaucous hue that is more or less present in most Conifers, shows itself most conspicuously in the Blue Spruce (Picea pungens glauca), in Cedrus atlantica glauca, in the new Cork Fir from Arizona (Abies lasiocarpa var. arizonica), and in Abies concolor violacea.
The Propagation of Conifers
Many mistakes have been made in propagating the Coniferæ, and to make matters still worse, the old erroneous doctrines are still preached and practised. The unpopularity of certain species of Abies, Picea, and Pinus is due to a great extent to the practice of grafting them on unsuitable stocks. For instance, the species of Abies are worked on A. pectinata, of Picea on P. excelsa, and of Pinus on P. sylvestris or P. Laricio. The varieties of P. excelsa are worked on that species. P. excelsa is not used for the other forms of spruce Firs to any great extent. In addition to this, such methods and stocks are still spoken of as the correct ones to use; though, to take one genus alone, what kind of a specimen Abies bracteata, A. nobilis, or A. concolor would make in twenty years' time if worked on A. pectinata we should not like to say—certainly very poor, even if they lived, which is doubtful. These are nearly always raised from imported seeds. It may be laid down as a law that species of Coniferæ should never be grafted but raised from seed, which can always be obtained through English firms. With varietal forms of Coniferæ that will not come true from seed or that cannot be struck as cuttings, grafting must be resorted to, and if young plants of the type species are used as stocks the results will be fairly satisfactory. In the case of some of the more highly variegated Cupressus, &c., grafting is really the best method of propagation, as these forms are mostly of weak constitution and are not satisfactory from cuttings. In the following list the best methods of propagation are given with each genus, together with special mention of those forms which are of indifferent growth though not difficult to propagate:—
Juniperus.—The Junipers should be raised from seeds, though some of them do fairly well if propagated by cuttings. The green and glaucous varieties of J. chinensis, J. excelsa, J. virginiana, and J. communis root easily from cuttings, or can be layered with success. The variegated forms are best grafted on stocks of the species they belong to, and J. Sabina (the Savin) and its varieties are easily raised from cuttings or layers, the latter being a very easy way of propagating them.
Cupressus.—This genus is divided into two sections, viz., the true Cypresses, represented by C. macrocarpa, C. sempervirens, &c., and Chamæcyparis, of which Cupressus lawsoniana is the best known species. With the former section seeds are the best means of reproducing the species, while the few varieties should be grafted on stocks of the parent species. The handsome C. macrocarpa var. lutea especially should be worked on the type, as it is practically a failure from cuttings, and if grafted on C. lawsoniana, as is sometimes done, it makes a short, stumpy bush instead of a typically tall columnar tree. In the Chamæcyparis section Cupressus lawsoniana, C. nootkatensis, C. obtusa, C. pisifera, and C. thyoides are the only species, though there are a host of varieties attached to them, the forms of the three latter species, in fact, including all the various plants more commonly known under the generic title of Retinospora. The species should be raised from seed, which is easily obtainable and germinates readily, or in default they will root from cuttings. The varieties, with a few exceptions, are quickly propagated by cuttings, those that require to be grafted being C. lawsoniana var. lutea, the variegated forms of C. nootkatensis, and C. obtusa vars. nana, nana aurea, and filifera aurea. The forms of C. thyoides also do well when raised from layers. We must not omit also such varieties of C. lawsoniana as Fraseri, Allumi, and one known in nurseries as Milford Blue Jacket.