Alpines, as a class, would better be left to the amateur with the time, money, and disposition to specialize. Most of them
take kindly to being transferred from a mile or more up in the air to sea level; the edelweiss, for one, grows here readily from seed, and the exquisitely beautiful Gentiana acaulis thrives in American rock gardens. But, on the whole, alpines do not do as well here as in England, where the summer climate is not so hard on them. When they flourish here, it is at the cost of a great amount of professional care.
THE WALL GARDEN
A wall garden is a perpendicular rock garden. But whereas a rock garden is of all things irregular, a wall garden has regularity. The wall need not be a straight line; it is better that one end should describe a curve, and rocks at the base may give it further irregularity. Yet it can never quite lose the air of man's handiwork. The prime object of the gardening on it is to reduce this air to a minimum.
The way to make a wall garden is to build a dry wall of rough stones—that is, a wall without mortar. Instead use soil and pack it tight in every crevice as well as behind the stones, which should be tilted back a little to carry water into the soil. This tilting may be accomplished with
small stone wedges. The best kind is a five-foot retaining wall, as there is then a good body of soil behind to which the roots can reach out through the crevices. But a double-faced wall may be made, if the situation demands it, by constructing parallel lines of stones and filling in solidly with soil.
Planting plan of dry wall, the dark portions representing the chief earth-filled crevices. The plants are: 1—Arabis albida; 2—Alyssum saxatile; 3—House leek (sempervivum); 4—Viola tricolor; 5—Armeria maritima