If the soil is slightly alkaline or slightly acid 
it will be satisfactory for the growth of most 
plants. If medium to strongly acid the majority 
of plants will respond to the addition of sufficient 
Limestone or Hydrated Lime which will bring 
the soil up to a slightly acid or neutral condition. 
This is not true in case weed competition is a 
factor as it is in the lawn. Lime should not be 
used on the lawn or on acid-loving plants. 
Alkaline conditions seldom exist in humid 
soils. Alkalinity is due to the presence of an 
excess of soluble salts in the soil and generally 
occurs under arid conditions. In humid regions 
Alkaline soils may be produced through the 
addition of too much hydrated or guick lime and 
it may at times be desirable to reduce the degree 
Rock Gardens 
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 cultural conditions, in part at 
least, approximating those under which they grew in nature, 
a rock garden is necessary. 
Apart from their value in providing a picturesgue and 
natural setting, a rock garden has several distinctly utili¬ 
tarian 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 evaporatiori. As many alpine 
plants grow in a situation where the soil is constantly 
moistened during the growing season with rain or snow 
water, the importance of providing a cool root run is im¬ 
mediately 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 collection 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 
extremes 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 collection of plants may be culti¬ 
vated. 
of this alkalinity. Aluminum Sulphate is the 
most efficient material for making a soil more 
acid. Broadcast this material evenly over the 
area at the rate of 2 pounds per 100 square feet 
and soak it well into the soil. It may be neces¬ 
sary to make several applications to obtain the 
degree of acidity desired. Care should be taken 
not to make the soil too acid. Acid compost 
material such as that made from oak leaves may 
be used if available. Such material acidifies 
soil very slowly. 
The final and most important requisite of a 
good soil is the proper amount of well balanced 
plant food. This is best done by the use of a 
good complete commercial fertilizer to be ap¬ 
plied at the approximate rate of 4 pounds per 
100 square feet. 
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 per¬ 
mitting 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 foundation 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 appear¬ 
ance. 
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 submerge 
the larger ones and build up from that point. This will give 
a more natural effect as well as provide better sites for 
planting alpine and rockery plants. 
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