June 8, 1918 • 



HOBTICULTTJBB 



557 



RHODODENDRONS. 

 The rhododendrons had a hard time 

 last winter and the wonder is that 

 after such a period of Arctic weather 

 they managed to survive at all. As it 

 v.as the foliage was pretty severely 

 damaged but the flowers were not ma- 

 terially damaged in most cases and 

 now in the vicinity of Boston, at least, 

 they are making a grand show while 

 the young shoots and foliage serve to 

 effectively camouflage the injured 

 leaves of the past season. 



Persons who desire to cultivate 

 these plants must remember that rho- 

 dodendrons including all azaleas, can- 

 not live in soil impregnated with lime. 

 Rhododendrons are not hardy north of 

 Massachusetts, and south of Pennsyl- 

 vania the summer sun is too hot for 

 them. The range therefore in eastern 

 North America where these plants 

 can be successfully cultivated is com- 

 paratively small, but probably the 

 northwest coast of North America 

 from southern British Columbia to 

 northern- California is as well suited 

 for these plants as any part of the 

 world, and there can be grown in ad- 

 dition to all the varieties common in 

 European gardens the Himalayan and 

 Chinese species which here in the 

 east can only be kept alive in glass 

 houses, and in Europe thrive only in 

 a few exceptionally favorable places 

 like Cornwall or in the neighborhood 

 of the Italian lakes. 



Rhododendrons, although they are 

 moisture-loving plants, do not thrive 

 in undrained positions; they do best 

 in soil in which loam and peat have 

 been equally mixed, although peat is 

 not always essential to the successful 

 cultivation of these plants. They 

 should be planted where the roots of 

 trees cannot take away moisture from 

 them, and the best position for these 

 plants is on the north side but not too 

 near coniferous trees. In such po- 

 sitions they are protected from the di- 

 rect rays of the sun in March and 

 April, for in this climate where the 

 roots are in frozen ground in winter 

 and therefore cannot take up mois- 

 ture, it is important to reduce as 

 much as possible winter and early 

 spring evaporation from the leaves. It 

 is this evaporation from the leaves of 

 evergreens growing in frozen soil 

 which makes it impossible to keep 

 alive many of .them in this country; 

 and this is the reason why it is de- 

 sirable to water thoroughly rhododen- 

 drons just before the ground freezes 

 in the autumn. Rhododendrons Im- 

 ported from Europe suffer here from 

 the stock on which they have been 

 grafted. The almost universal custom 

 among European nurserymen is to u'se 



PATRIOTS 



Rhododendron ponticum as the stock 

 for these plants because it is easily 

 and quickly raised and readily graft- 

 ed. R. ponticum is not at all hardy 

 here, and there i« little doubt that our 

 want of success with rhododendrons 

 imported from Europe is due, in part 

 at least, to the stock on which they 

 have been grafted and that the grad- 

 ual or sudden death here of large 

 plants which have been uninjured by 

 cold or drought for twenty or thirty 

 years is due to this cause. 



The familiar rhododendrons of New 

 England gardens are so-called Cataw- 

 biense hybrids and were raised in 

 Europe many years ago by crossing 

 R. catawbiense, a native of the high- 

 est summits of the Appalachian 

 Mountains, with Himalayan species, 

 notably the scarlet-flowered R. ar- 

 Itoreum. It might be expected that 

 plants obtained from these crosses 

 woould be hardy in proportion to the 

 predominance of the American plant 

 but, judging by the color of the flow- 



ers, this is not always true. Varieties 

 like Atrosanguineum, Charles Dickens 

 and H. W. Sargent, which have flow- 

 ers as bright red as those of R. arbo- 

 reum, are among the hardiest of all 

 garden rhododendrons; but varieties 

 with white or pale flowers are more 

 tender than those with rose pink or 

 purple flowers which most closely 

 show the influence of the Cataw- 

 biense parent; and unfortunately the 

 varieties with light-colored flowers 

 marked at the base with large brown 

 or chocolate-colored blotches, like 

 Sapho, are not at all hardy here. 



The hardiness of these hybrid rho- 

 dodendrons can only be determined 

 by trial, although in selecting varie- 

 ties for trial it is safe to assume that 

 plants with broad leaves resembling 

 those of /?. catawbiense, like Ever- 

 estianum, Mrs. C. S. Sargent, Roseum 

 elegans, Henrietta Sargent, Cataw- 

 biense album, and all the varieties 

 with light or dark purple flowers are 

 likely to prove hardier than the plants 



