MAKING THE ROGK GARDEN 15 



Others, again, like the cool cleft of a rock-face facing 

 north, or will clothe little mounds in half shade, while 

 still others need deep soil that is always moist. 



The Choice of Stone. The choice of stone affects 

 the appearance of the rock garden to a remarkable degree. 

 It is better to have a few pieces of good stone than an un- 

 limited number of pieces of poor stuff, and if they must 

 be few, let them be big, for even a few big rocks, boldly 

 placed, will give such character that many smaller stones 

 fail to do. If one's garden is in a neighbourhood where a 

 certain kind of stone is plentiful, that generally will be 

 chosen. It is a mistake to use numerous kinds of stone. 

 Make choice of one kind and use it throughout. One 

 should, if possible, avoid hard rocks, such as those of 

 granitic type, for plants do not like them, and derive 

 no help at all from their impervious surface. Those 

 that are porous and absorbent are most suitable, for 

 the plants' roots cling to them readily, and find abundant 

 moisture in their cracks and crevices. Moreover, such 

 rocks soon become weathered, while the hard stone 

 never does. One should try to avoid very soft stone, 

 for it is apt to crumble and disintegrate from the effects 

 of the weather. There are many kinds of rocks, chief 

 of which are sandstone and limestone. Both vary very 

 considerably, the former from the light-coloured, attrac- 

 tive stone of Yorkshire and Cheddar, to the brown sand- 

 stone-like material that is found in Gloucestershire. 

 The light limestone, especially when weathered, is most 

 admirable material for rock building ; its appearance 



