Hire an ordinary labourer no need of a high-priced stonemason or expert gardener. Provide him with a lot of alpine or rock-loving plants. And as each stone is laid, lay in some of these plants, sprinkling the roots with a little fine sandy soil not enough to prevent the stones from setting firmly, but just enough to encourage the roots to run clear to the end of the wall in search of food. Back of the wall pack a layer of gritty earth. The plants will soon find this and revel in it, for there they will have that combination of perfect drainage and never-failing moisture which they can get nowhere else on your place, save in a well-constructed rock garden. Thus you will be able to grow many choice flowers which would perish on level ground because of winter wetness. Famous examples of this in England are the wallflower, snapdragon, and Cheddar pink.
Even better than this scheme for America is a kind of wall garden I saw at Waltham Cross, at the home of Sir Hugh Myddle-ton. The lay of the land required a wall only two or three feet high to keep a bank of earth from tumbling into the driveway. When a wall is as low as this it is possible to use more earth than stone and thus get enough soil in the wall itself to support a luxuriant growth of vines. But, of course, it is a great advantage to have behind the wall an inexhaustible supply of moisture and plant food. The wall I speak of had just enough rocks in it to hold the bank together and these rocks were all but obscured by vines and flowers. It was pleasant, however, to catch a glimpse of the rocks occasionally, as they gave a feeling of stability. I should not expect so crude an arrangement to be effective for the rock roses or helianthemums which glorify English walls of the same character, or any of the more difficult alpines, such as edelweiss, gentians, or saxifrages. The proper thing for such is a scientifically constructed rockery. But this plan of having more earth than stone gives us a chance to plant long low walls with great stretches of easily grown perennial flowers sheets of golden tuft in April, fragrant breadths of rock-cress and woodruff in May, cool lines of Cerastium tomentosum or "snow in summer," cascades of wild pinks in June, tender blue alpine forget-me-nots, dainty masses of Kenilworth ivy, and hundreds of little blue spires of veronicas all of which have the true alpine feeling. (All these you can buy in the form of plants in spring or raise from seed which is best sown in a coldframe in July.)
If you will take a slow automobile or trolley ride this afternoon and examine the stone and brick retaining walls that line the road in city and country your eyes will be opened to a sickening amount of ostentation and stupidity. For people who have to deal with sloping land generally do one of two foolish things.
The stupid thing to do is to make steep banks of grass with sharp, formal edges. These terraces are difficult to mow and costly to maintain in perfect condition. At best they are dull, compared with a real lawn or with the beauty that may be had by retaining natural contours and planting the banks with flowering shrubs and vines. For these have longer roots than grass and are therefore better adapted for holding the soil and preventing washouts. And a border of shrubbery makes a lawn more beautiful, because it acts like the frame of a picture.
The ostentatious way to treat sloping land is to build a fancy stone wall and leave all its surface exposed so that people may be impressed by the amount of money spent thereon. If mortar is necessary it is better to build strongly but simply and partially cover the wall with a variety of climbers and trailers. Even when we do this how little imagination and taste we commonly employ! We use miles of Japanese ivy as if it were the only vine in the world! Yet if the wall is beautiful it is a great mistake to hide it altogether because wall and vine could each set off the other's beauty. Moreover, Boston ivy (or ampelopsis) clings so tightly that it emphasizes every artificial line instead of softening it. Again, it rarely occurs to us to plant vines above a wall and let them hang down. Yet our own Virginia creeper is far more beautiful as a trailer than as a climber; witness the picture at plate 39. And every one who has to build retaining walls can transform them into veritable hanging gardens, simply by planting in the earth above them wild grapes, Virginia creeper, wild clematis, multiflora roses, Hall's honeysuckle, and bitter-sweet. A variety is better for the roadside than a monotonous expanse, and the combination just mentioned will give beauty the year round.
Mind you, I do not advocate a high brick wall around the whole estate, such as you see everywhere in England! It will be a long time before every country roadway in America is an unbroken vista of high walls and hedges. I doubt if we shall ever come to that, for it implies the aristocratic spirit, while garden and retaining walls do not. But whenever it is necessary to build a wall around any property and it is impossible to plant vines above, my advice is this: Plant flowering vines wherever there is plenty of sun, and on the shady walls plant English ivy and climbing euonymus not the trifling variegated kinds of euonymus, which fall an easy prey to San Jose scale, but the green, round-leaved kind (Euonymus radicans var. vegetus), which eventually is garlanded with red berries that are full of cheer all winter. Of these two evergreens we can hardly get too much; for never in the North will they thrive as wantonly as in England, and never will our climate deal as lovingly with architecture as the English mosses, lichens, and algse. We shall have to plant millions of climbing euonymus and millions upon millions of English ivy before American roadsides may attain the classic dignity and beauty of old England.