324 STUDIES IN GARDENING 



teriorate in cultivation. Of the low-growing spring 

 Phloxes there are many varieties, but none so beauti- 

 ful or compact as the white Phlox Nelsoni and the 

 pink P. Vivid. These should be mixed among bold 

 rocks and in a light rich soil. In damp or shady places 

 they are apt to die off in winter. If they are top- 

 dressed with leaf-mould the shoots will root, and this 

 is the best way to increase them. 



There are several Alpine Ranunculi, but none more 

 beautiful or vigorous than R. amplexicaulis, which 

 likes a cool place and a soil of loam and leaf -mould. 

 Of all the Violas, the new Viola gracilis from Greece 

 seems the most valuable for the rock garden. It ap- 

 pears to be hardy and vigorous and has bright but 

 delicate purple flowers. It should be grown in a warm 

 place and light, rich soil, at least until its capacity 

 for standing our winters is better known. Among 

 Veronicas we choose V. prostrata, among Potentillas, 

 P. alba both most beautiful plants not so often 

 grown as they should be. P. alba flowers for six months 

 of the year, and will grow almost anywhere. In a 

 large rock garden space should be found for Nierem- 

 bergia rivularis, which in England thrives best in a 

 flat, sunny, well-drained place and should be top- 

 dressed with leaf-mould when it starts into growth 

 in spring. It increases at a great pace, and flowers 

 for a long time. Dryas octopetala also needs a large 

 space, and flowers most freely in full sun when it is 

 protected from drought by large rocks. It likes a 

 strong dose of lime in the soil. There are many good 



