Rockeries
Where alpines and perennials are cultivated in any great quantity, it is essential that some sort of a Rockery should be provided for the accommodation of the rarer and dwarf-growing species. It may be on a small or an unlimited scale, according to the extent of the collection; in any case, this style of gardening affords very great interest, especially when the plants can be induced to succeed. Besides alpines and dwarf perennials, there are numerous other subjects that may often be appropriately introduced, such as hardy Ferns, Yuccas, compact-growing shrubs, Junipers, hardy Heaths, &c. When constructing a Rockery, the principal object should be to provide situations, and allow sufficient space amongst the stones for the plants to grow. The outline or shape can be formed by building up such ordinary soil as may be at command; the stones can then be embedded over any part of the surface desired, and a new compost added at the time the plants are arranged and inserted. Rockwork is generally constructed of stone, if this is procurable; but frequently other substitutes, such as old bricks, clinkers, &c., have to be utilised. Little can be said respecting the proper arrangement, as this varies, in almost every individual case, to suit the situation, plants available, and the surroundings. A background of some sort is desirable, for affording shelter and protection from cutting winds; Rhododendrons are well suited for the purpose, as they grow tall if allowed, and their roots never spread far enough to rob the rock plants, as would those of large trees. To meet the requirements of the numerous subjects available for planting on a Rockery, it is requisite to provide various aspects and different kinds of soil; and, in planting, a knowledge of the habit each plant assumes is necessary, in order to dispose of all to the best advantage for producing a future effect. A general fault is to allow too little rooting space, by making the pockets--as the divisions between the stones are generally called--too small. This should specially be avoided; if roots cannot get down and establish themselves, the plants soon become dried up in hot weather, particularly on sunny exposures. The class of plants which thrive best on rockwork--indeed, there are many that could scarcely be grown except in such a situation--is a very extensive one, and includes a large proportion of beautiful and most interesting subjects. If dwarf shrubs and other plants, also hardy bulbs, are introduced, the variety that may be represented in the limited space which a Rockery usually affords is really surprising. A very large proportion of the genera Saxifraga and Sedum make excellent rockwork plants. Other remarks on this subject may be found under Rock Garden in the article Garden.