iv.] THE ROCKERY AND WALL-GARDEN 75 



the wall well into the bank. The more porous and rotten 

 the stone the more welcome as nourishment and root-hold 

 it will be to the tiny plants, whose roots are to find their 

 natural home in its chinks, and even if a stone or two 

 should crumble right away in a few years' time, the rest 

 will hold, and the space left will make a little cavity where 

 some small fern will live happily. 



As it is being built, the wall should be planted with 

 hardy ferns. The long fibrous roots of such sorts as the 

 Parsley may be spread out between two flat stones, with 

 but a sprinkling of turfy mould between. The Polypodies 

 had best be placed where their strong root-stems shall have 

 ample opportunity of spreading themselves over the 

 surface. The Welsh and Cornish are the best of all 

 Polypodies, but the Limestone, the Oak, and the Beech, 

 though not so easily naturalised, are lovely plants. Then 

 there are the Hartstongue, Ceterach, Asplenium, and 

 Wallrue. These last three like lime, and so a barrow of 

 old mortar-rubbish may be thrown in where they are to be 

 planted, so that they may have a layer of their favourite 

 soil. 



Each course should be laid fairly level as to its front 

 top edge, the earth behind then carefully rammed into the 

 spaces at the uneven backs of the stones, and a thin layer 

 of earth over the whole course, where in a built wall the 

 mortar would have been. This supplies both a " bed " for 

 the next row of stones and soil for the plants which are to 

 grow in the joints. 



The face of the wall slopes backward on both sides 



