Alpine Rhododendrons possess great depth and richness of leafage color. Belonging to the mountain ranges of Europe , they are perfectly hardy and   well fitted for association with Alpines and rock plants. R.chamaecistus, an exquisite little shrub, only a few inches high, may be grown in the highest situations in sandy loam with a slight mixture of peat. It is always found naturally on the limestone formation, and is impatient of granite soils. Other dwarf kinds are R.myrtifolium, Hybridum, and Odoratum, the latter a scented variety.

The scarlet flowered Swiss Rhododendrons (R.ferrugineum and R. hirsutum) known also as Alpine Roses, are of larger growth, and do best in peaty soil in the lower parts of the rock garden. All the dwarf Rhododendrons except Chamaecistus form suitable backing plants for bright patches of herbaceous flowers.

Included among these dwarf evergreens is the Partridge Berry (Gaultheria procumbens), with drooping white flowers and winter berries. It succeeds in sandy soil in partial shade, and is easily increased by division. The other Gaultherias are too large for any but rock gardens of considerable extent.

Above the groups of small plants and the hard edge of the topmost rocks, there may be planted those hardy flowering shrubs which are happy in the sunniest and most exposed positions. An unbroken line of upstanding foliage is not desirable, but bold groups in several places, with an occasional fringe of overhanging branches. When the rock mound or bank is of only slight elevation we may in this way screen distant objects from view, and give an air of completeness to the whole design.

If the upper part of the rock garden is tenanted only by plants of small stature, it almost appears as though the object of such dwarfing was to enable an uninterrupted view of scenes beyond. This, however, is unfortunate, a full measure of beauty is to be found among the Alpines and rock flowers themselves, and a degree of seclusion and privacy is necessary for their full appreciation.

In the hottest situations where nothing else will thrive, various kinds of Broom and the double and dwarf Furze may be planted. It is a mistake to look down on the latter shrub because it grows wild on English commons, there are few more glorious sights in Nature than a golden sea of Furze beneath a stormy sky.

The double variety is to be preferred to the single wild kind, lasting longer in bloom and giving more vivid color effects. The dwarf Ulex nanus flowers at midsummer, and is suitable for small rock gardens. Furze requires regular pruning to keep it within bounds, and young plants are much easier to establish than older specimens.

The Brooms (Cytisus) are a beautiful family, from the strong growing C.albus (Portuguese Broom) with its long slender branches wreathed with white flowers, to the tiny C.ardoini, a miniature Alpine shrub. The Spanish Broom flowers freely in hot, dry soils, and even our British Broom (C.scoparius) is worth growing on the wilder outskirts of the rock garden. Of different habit to others of the genus, the Purple Broom trails along ledges and falls in dense curtains over large boulders.

It is unfortunate that the Rock Roses (Cistus) are not more hardy, as they are particularly suited to a dry sandy soil in the upper parts of the rock garden. They are easily propagated, and a stock of new plants can be raised from time to time, so as to make good any losses. The flowers last but a single day, but are borne in such profusion that this peculiarity is hardly noticeable. C.laurifolius and C.cyprius are among the best.

The Genistas (Rock Broom) are a large family, and contain many varieties for the rock garden. G.germanica is free flowering, and forms a shrub of moderate dimensions. The double form of G.tinctoria, G.aspalathoides, G.praecox and G.andreana are among those from which a choice may be made. All the Genistas are readily increased by seed, are indifferent as to soil, and need transplanting before the roots become too coarse and straggling.

Owing to the practice of crowding the hardy junipers among free growing evergreens in the shrubbery, their value is seldom realised. When grouped together in the rock garden it will be seen that they are by no means unworthy, the common Savin (J.sabina) is graceful and has feathery branches. J.prostrata is a good sub-variety.

On warm, sunny banks a few plants of Lavender and Rosemary. The older bushes look best, the trim balanced form of the young plants having given place to a freedom of gnarled and twisted branches, lightly flecked with glaucous leaves. Both the white and blue Lavenders are worth cultivation. Apart from other reasons there is a charm attached to these old ­fashioned flowers, which gives them a special claim to our consideration.

Rock shrubs of trailing character are of the greatest possible value in forming connecting lines between upright groups. The beautiful Rocksprays (Cotoneaster) drape the larger stones and boulders, and the evergreen kinds are like cheerful garlands on the cold slopes of the winter rock garden.

The Wall Cotoneaster (C.microphylla) is quite hardy, and produces a pretty effect with its deep green foliage, white blossoms and crimson berries. C. horizontalis (Plumed Cotoneaster) is brilliant in autumn, with vivid scarlet berries and flaming leaves. The Rocksprays are of the easiest culture and do well in almost any soil. With other trailing shrubs the graceful Muhlenbeckias may be associated, complexa and varia being chosen for preference.