28 MASSACHUSETTS HORTICULTURAL SOCIETY 



were considering in the construction of the rock garden. The 

 reader has only to look about his neighborhood to see the slipping 

 down effect of trees and shrubs, and how poor the grass is on a 

 sunny bank. 



If, to avoid this, retaining walls are put in, a new field for the 

 planting of alpines appears, and we come to what in England 

 is called Wall Gardening. There dry walls are used. In this 

 country; a dry wall, meaning a wall built of stones without cement, 

 gets pushed out of shape by our frosts and looks in time like a 

 wall in a nightmare, not at all a suitable border for a road or 

 decoration for a lawn. Miss G. Jekyll and other English authori- 

 ties recommend dry walls most highly, but they have very little 

 frost to contend with. In this country one can manage by having 

 the wall thoroughly cemented at the foundations and for eighteen 

 inches from the ground. Then, if half the other stones are made 

 fast with cement, say roughly every alternate square foot, the 

 other half may be planted and will give an excellent effect, probably 

 quite as good as if it were entirely covered with plants. 



It is very important in making such a wall to watch the men 

 constructing it, otherwise they will throw in large stones, instead 

 of earth mixed with small stones, behind the wall. The whole idea 

 of a dry wall is that the plants should be able to root through 

 it into the bank of earth behind. If, when the tender roots push 

 back, they find only stones, the plants will naturally die. It 

 is necessary to enrich the soil and see that it has humus well mixed 

 with it, so that the plants can thrive. In building the dry wall, 

 as much care should be taken to ram down the soil and leave 

 no air spaces as in constructing the rock garden. It is really the 

 same idea, and it is also necessary to have the stones tip upward 

 a little, so that the rain may reach the plants between them. This 

 is called a battered wall and can be done by putting small stones 

 between the front of larger ones and carefully filling and ramming 

 the crevices between the soil. When finished, this should all be 

 perfectly firm. 



Many and varied are the plants which can be grown in the re- 

 taining wall, and if it faces north our native plants, such as ferns, 

 columbine, the small two-leaved Solomon seal (Smilacina bi- 

 folia), and violets, with a few harebells, would make a lovely 



