CULTIVATION OF ALPINE PLANTS 53 



pot, so that the earth enclosed by them may remain 

 firm, and so that all rain may run down by the roots 

 of the plant. 



Alpine plants which increase by underground run- 

 ners, and which are liable to suffer from drought, are 

 much benefited by a top-dressing of silver-sand and 

 leaf-mould when they are just starting into growth 

 in the spring. This top-dressing is peculiarly val- 

 uable and indeed essential to all delicate sur- 

 face-rooting plants, as it protects them from drought 

 and gives them just the nourishment they require. 

 It should be applied very carefully and worked in 

 among the growths with the fingers, and may be re- 

 peated later on in the summer if the earlier dressing 

 has washed away. A top-dressing of this kind is a 

 natural remedy, since Alpine plants in their native 

 homes are often subject during all the warm part of 

 the year to a perpetual wash of sand and grit and 

 vegetable matter; and some of them, such as the smaller 

 primulas, have a habit of growing out of the ground, 

 which is no doubt a natural device to protect them 

 from being smothered by the wash of earth. Such 

 plants will soon die if they are not top-dressed. Al- 

 pine plants with very woolly leaves are also the better 

 for a top-dressing of pure grit in the autumn as this 

 absorbs the moisture and prevents their suffering from 

 it. The Fairy Forget-me-not (Eritrichium nanum) 

 is an extreme instance of the plants which need the 

 kind of culture described above. It and a few other 

 plants of the high Alps have never yet, we believe, 



