102 ALPINE FLOWERS AND ROCK GARDENS. 



is active, and hence roots make for them and cling to 

 them. Many plants will run a network of roots and 

 even stems over the cool, damp surface of stone. 

 Agriculturists find that in districts where the ground 

 is stony, moisture-loving plants like turnips will often 

 thrive in dry seasons, while on fine soil they will fail. 

 For this reason small stone chips may be mixed hber- 

 ally with soil in making a rock garden. In winter 

 evaporation is less active, and finely pulverised soil 

 becomes sodden in wet weather. If damp, pasty soil 

 sticks closely to the " collar '' of the plant (the " collar " 

 is the point between root and leaves which is in con- 

 tact with the top layer of soil) the latter is apt to decay. 

 With plenty of gritty soil round the collar this binding 

 does not take place. The water drains through to 

 the roots. For this reason top-dressing with grit in 

 autumn is good practice, and it is calculated to be of 

 special advantage in heavy soil, and where sufficient 

 care has not been taken to make the compost gritty 

 at the time of establishing the rock garden. 



In respect to this most important matter of soil 

 and top-dressing, one of the most successful of all 

 rock-gardeners, the late Rev. C. WoUey-Dod, may be 

 quoted : " Good loam, with a little humus in the form 

 of leaf mould or peat, and half or three-quarters of the 

 bulk composed of stone riddhngs from the nearest 

 quarry, and varying in size from that of rape seed to 

 that of horse beans, make up a good soil with which 

 most Alpines are quite contented. Rough surface- 

 dressing is a thing in which all Alpines delight, as it 

 keeps the top of the soil sweet and moist, and prevents 



