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I T is correct to assume that the ideal rock garden 
is one capable of supporting a healthy growth of 
alpine and rock plants. In order to display them in 
an appropriate setting and to provide proper cul¬ 
tural conditions, in part at least, approximating 
those under which they grew in nature, a rock gar¬ 
den is necessary. 
Apart from their value in providing a picturesque 
and natural setting, a rock garden has several dis¬ 
tinctly utilitarian functions to perform. They help 
to keep the ground cool, they conduct moisture to 
the roots of the plants and prevent in part its loss by 
evaporation. As many alpine plants grow in a situa¬ 
tion where the soil is constantly moistened during 
the growing season with rain or snow water, the 
importance of providing a cool root run is immedi¬ 
ately obvious. Rocks serve to give shade and shelter 
and aid in promoting the efficient drainage which 
is so necessary. Also they hold up the soil making it 
possible to provide a variety of contours in the 
garden. 
The forms that rock gardens take are many and 
varied, ranging from the many positive directions 
made solely for the purpose of growing a large col¬ 
lection of alpines and rock inhabiting plants, to the 
type designed purely for a landscape feature in 
which the plants are merely incidental decorative 
material. The ideal garden lies between these ex¬ 
tremes and consists of a construction in which the 
rocks are arranged artistically, usually with the 
same relation to what one might find in nature, and 
placed in such a way that a reasonably large collec¬ 
tion of plants may be cultivated. 
As a general rule, the site of the rock garden 
should be in the open, not subject to the drip of trees 
or to have to compete with their root systems. 
Preferably the subsoil should be a porous nature 
permitting the rapid drainage of surplus moisture. 
This is true in spite of the fact that some alpines 
thrive in boggy situations. Where subsoil is not of 
this type, it is advisable to place a six-inch founda¬ 
tion of cinders before constructing the rockery. 
Weather worn limestone of irregular shapes is 
perhaps the most pleasing material for construction 
and the easiest to work with, but weathered rocks of 
almost any kind can be used to advantage, provided 
they are angular and blocky in form with a natural 
color and of pleasing appearance. 
Having decided on the location and knowing the 
kind and amount of rock available, the next step is 
to remove the top soil from the area. This top soil is 
the medium in which the rock plants will be planted, 
therefore should be saved. Next the subsoil should 
be shaped up so its contour roughly conforms with 
the general outline the rock garden is to assume. Its 
drainage is necessary, it is advisable at this time to 
put in the six inches of cinders. 
In placing the rocks it is advisable to partly sub¬ 
merge the larger ones and build up from that point. 
This will give a more natural effect as well as pro¬ 
vide better sites for planting alpine and rockery 
plants. 
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