6 



CASSELL'S POPULAE GASDENrnG. 



the other in tolerahly close iDroximity, as thus the 

 effects of all will be heightened alike literally and 

 figuratively, for from the water-line to the top of 

 the tallest rock is of necessity the greatest possible 

 difference of altitude within reach. The smooth 

 water also contrasts sharply with the rough and 

 rugged rocks, and the contrast would be heightened 

 were the rocks to plunge rather abruptly from the 

 highest point to the surface of the miniature pond or 

 lake, however small. The effect would be still more 

 striking were the rocks crowned ^-ith such stiff and 

 formal plants as Echeverias, Yuccas, Dracaenas, 



within the limits of a few yards. All that is needful 

 is to place the sun-losing subjects on the southern 

 and the shade-lo^-ing ones on the northern sides of 

 the up-towering rocks, such as those shown in the 

 illustrations. 



In planting into the soil itself, as here recommended, 

 great care must be taken in the placing of the rocks 

 afterwards, to afford the fi-ee access of rain to the 

 roots. With sufficient drainage beneath, there is no 

 fear of any excess of rain from above ; but if stones 

 are so placed as to tlu'ow it oft' the roots, the Alpiae 

 plants must needs di'oop and suffer in consequence. 



Palms, tall Ferns, or Aloes, and the latter furnished 

 with Water Lilies, Irises, or Musk Marigolds. But 

 mere swamp — that is, neither good rock, bog, nor 

 clean water — at such points as a, h, and c would be 

 alike objectionable on grounds of taste and culture. 



Shade and Shelter. — The system of forming the 

 bases of rockeries of earth-mounds of considerable 

 boldness, also affords the utmost possible diversity of 

 site and aspect within a limited area. This is of great 

 importance in the cultivation of Alpines as well as of 

 ferns. It is too generally assumed that the former 

 thrive best in full sunshine, and the latter in the 

 shade ; but the fact is that not a few of both families 

 of plants thrive best in the sun and others in the 

 shade. With a rolling-bank running north and 

 south, sun and shade may be provided at pleasure, 

 and thus each family of plants be proA-ided with, as 

 far as possible, its natural conditions. Even where 

 mere, pieces of rock are set up, as in Figs. 1, 2, 

 and 3, shade and shine may each be commanded 



Keeping the Crowns well above the SoiL 



— Though most of these plants enjoy an abundance 

 of moistm-e, few of them can endui-e water resting 

 on their crowns. The crowns are not only the chief 

 centres of beauty in rock plants, but also their 

 source of weakness. They are keenly susceptible 

 of cold, and easily injured by any excess of water. 

 Considering from whence they come, it may seem 

 absurd to affirm that any of these plants should 

 succumb to the cold of oui' climate; but they do. 

 They miss their snow coverlet, which seldom sinks 

 much below 32°, and their slightly wanner bath of 

 snow-water a few degrees above it ; and hence, when 

 exposed to five, ten, or fifteen degrees of frost, not a 

 few of them perish from cold. They suffer all the 

 more if the frost comes down upon them in a very 

 wet state ; hence one powerful reason why the 

 crowns should be slightly elevated above the sur- 

 rounding sm-face. 



One great objection to common pocket-planting is 

 that, as a rule, the sides of the pocket must of 



