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GARDENERS' CHRONICLE 



doing so because of the fact that thc-ir neigiiboi's do not succeed 

 with them. Including azaleas, there are some ten species of 

 Rhododendrons native to this country which are perfectly hardy, 

 in the Northern States, and I have yet to lind a district in the 

 country in which they cannot be made to flourish. Correct soil 

 treatment after planting is important with everything, but with 

 no class of plants is the importance greater and more vital than 

 with Rhododendrons, and their failure to thrive is invariably due 

 to either neglect, or, which is worse, to wrong treatment. 



The correct soil treatment after planting is learned by going to 

 Nature and seeing plants growing in their native homes. In 

 the case of some species we may find specimens thirtj' and forty 

 feet tall growing on the mountain side with a very small depth 

 of soil under them. From the day, we know not how many 

 hundreds of years ago, the seedling plant from which these orig- 

 mated, started, there has been an annua! fall of leaves upon them, 

 the decay of which has resulted in the gradual accumulation of 

 the bed of leaf mould in which these specimens are growing. 

 The proper treatment of these plants cannot be more plainly 

 indicated, but some people are either ignorant of Nature's meth- 

 ods or they think that it is she who is ignorant of the right thing 

 to do and they compel their Rhododendrons to e.xist with nothing 

 but bare soil under their branches, a condition of things which 

 is inaintained by continuous raking in what in this case, as well 

 as in others, amounts to a craze for ultra tidiness. While pro- 

 vided we have a soil which is free froin lime and is neither pure 

 sand nor pure clay leaf mould is not absolutely essential to plant 

 Rhododendrons in it is essential that they have the soil in which 

 they are growing annually covered with leaves and that these 

 leaves are allowed to remain all the year. Ten or twelve inches 

 is not too thick a covering of leaves to apply every year some 

 time between October and Christmas. Combined with this an- 

 nual leaf application there will be a continual leaf decay with the 

 production of leaf-mould into which plant roots will penetrate. 



Soils have to be considered not only from the standpoint of 

 their physical condition and their chemical contents, but also 

 from that of their biological characters. Unless the biological 

 character of a soil — in other words its bacterial content — is suit- 

 able for the plant we w'ish to grow, which suitability is based 

 upon the symbiotic influence which one form of plant life has 

 upon another, the plant cannot thrive. The term symbiosis is 

 used today in a somewhat more extended manner that hereto- 

 fore. Strictly speaking we think it should only be applied to ' 

 \he intimate association of two distinct organisms with benefit 

 .0 both or at least to the plant we desire to grow ; but the use 

 of the word in connection with pure parasitism having an harm- 

 ful effect upon the higher fomi of plant life, appears scarcely 

 warranted. It can scarcely be doubted that all plants require 

 more or less, the existence of their own special bacteria in the 

 soil, and that the species and nuinber of these micro-organisms 

 contained by the soil is just as important a consideration as its 

 physical and chemical characters ; at the same time, however, it 

 appears that these organisms are more necessaiy to soine plants 

 than to others. Bare ground is undoubtedly inimical to soil 

 bacteria. In forestry the vital importance of preserving the for- 

 est-floor is fully recognized, which floor has been formed by the 

 decay of the leaves and needles of the forest trees, and the dif- 

 ficulties in reforesting when this floor has been destroyed are very 

 great ; difficulties which are mainly due. to the absence of bacteria 

 which have either been scorched out by the sun shining upon 

 the bare ground, or washed away with soil denudation. The 

 practice of raking away all leaves from under shrubs and trees 

 is the reverse of beneficial ; with the ordinary deciduous shrubs 

 and trees that root more or less deeply, the leaves should at 

 least be spaded in, but with many subjects like .Rhododendrons 

 which are surface rooting, spading cannot be done without harm, 

 and in any case these, as pre^'iously stated, should always have 

 more leaves added yearly and left alone to decay. Needles of 

 conifers should never be raked away, as their decay is absolutely 

 necessary to the life of those microscopic plants whose symbiotic 

 action has such beneficial eft'ect upon growth of coniferous plants. 



In dealing with a piece of ground devoted entirely to crops, 

 like vegetables, the soil can be treated as a whole. Of the two 

 extremes a very sandy soil on the one hand and a heavy clay 

 on the other, it is difficult to say which is the worse. One of a 

 .landy nature can be worked at any time : it is an insatiable de- 

 vourer of manure, and is tlie poorest in natural plant food; but 

 it is capable of giving earlier Spring crops as it soon warins up 

 after Winter. A clay is always colder: seeds cannot be sown so 

 early in the Spring: it is more difficult to work, and a few days 

 must alway.s be allowed to elapse after rain before handling it; 

 but when handled properly it withstands drought and is capable 

 of carrying heavy crops. 



While soils containing a inore or less large proportion of 

 clay — a pure clay does not exist — require more labor e.xpended 

 upon theiu than do those of a sandy nature, they require less 

 manuring than the latter and plant-food is not so readily washed 



out of them. Every gardener who has had much experience in 

 handling soils of differing physical characters is aware of the 

 great advantages in having one which is easily worked in spite 

 of perhaps some chemical disadvantages connected with it. 



The most obdurate clay soil and one running very closely to 

 pure sand, can be so handled as to ameliorate their respective dis- 

 advantages, and various means to this end will be discussed in 

 the next lesson. 



NOTES FROM ARNOLD ARBORETUM BULLETINS 



(Continued from page 614) 

 pure pink flowers which open in early Spring. It grows ap- 

 parently equally well in full exposure to the sim and in the shade 

 of pines and other trees. There is a w^hite-flowered form with 

 thinner, less rusty brown leaves, which is still rare in gardens 

 and appears rather less hardy than the pink-fiowered type. R. 

 minus grows from low altitudes, as at the locks on the Savannah 

 River above Augusta, Georgia, up to altitudes of thirty-fve hun- 

 dred feet on the Blue Ridge of North Carolina. It is a shrub 

 sometimes ten or twelve feet tall, with leaves covered below with 

 glandular scales and pink flowers, which in northern gardens do 

 not open until the end of June, and after the shoots of the year 

 have nearly attained their full growth. A fine variety of this 

 species (var. Harhisonii) from northern Georgia with larger 

 flowers is not yet in cultivation. The two European species R. 

 hirsutum and R. fcrrugincum are dwarf shrubs with small pink 

 or carmine flowers, the fonner with branches covered with hairs 

 and leaves glandular hispid on the lower surface, the latter with 

 glabrous branchlets and leaves covered below with rusty brown 

 scales. Of the two R. hirsutum has taken more kindly to culti- 

 vation, at least in the Arboretum. It can grow in soil impreg- 

 nated with lime. R. smirnon-ii, a native of the Caucasus, is said 

 to become a tree sometimes twenty-five feet high ; in the Arbore- 

 tum, wdiere it is hardy, it is a shrub four or five feet high, with 

 oblong, acute leaves dark green above and covered below with a 

 thick, yellowish or tawny felt -which also covers the branchlets, 

 and protects the leaves from the attacks of the lace wing fly. The 

 flowers are bright pink and beautiful. Of the hundreds of species 

 of Rhododendron which grow in China only the northern R. 

 niclanthum has up to this time showed itself able to support the 

 New England climate. It is a straggling shrub with small leaves 

 and small compact clusters of small white flowers which give to 

 the plant the appearance of a Ledum. The Japanese R. brachy- 

 carpum is a handsoine shrub with leaves which resemble those of 

 R. cataicbicnsc, and rather compact clusters of large pale pink or 

 pale straw-colored flowers. 



"NOTHING NEW UNDER THE SUN." 



Shortly after the literature was circulated by the National 

 .Association of Gardeners to create public sentiment against the 

 sign board nuisance which threatens to mar the scenic beauties 

 along our highways, a communication was received from one of 

 the national association of sign board interests offering evidence 

 that its industry is one of the oldest in the world's history, just 

 as gardening is proclaimed to be one of the oldest in the world. 

 In the year 1666, Charles II. in the seventh year of his reign, 

 initiated an act. "That in all streets no sign lioards shall hang 

 across same." This regulation was closely followed in France in 

 1669. The ancient Egyptians perhaps excusably had but slight 

 use for signs. The first distinct evidence we find, however, is 

 with the Romans. Not only have the actual original signs been 

 recovered, but in many places we find Horace, Phsedrus and 

 Cicero referring to signs. Ph«drus mentions the "painted signs" 

 as "signs we see painted on the walls of taverns ;" while Horace, 

 the beloved poet was so moved by a wall-sign which portrayed a 

 fight that he wrote. "I admire the men painted in red or black, 

 moving as if they were actually living and fighting as if actually 

 real." Cicero, the great Roman orator, says while deriding some 

 opponent presumably, "I shall show you how you look. (To 

 which he answered, 'Please do.') Then I pointed my finger 

 towards a cock painted on a sign board." These and inany other 

 quotations seem to show that the outdoor advertising business 

 was at least a lusty infant when Caesar was fighting his Gallic wars. 



While the foregoing is illuminating, it does not permit any 

 license for the wanton desecration of our highways by sign board 

 vandals or any reason why the campaign inaugurated to combat 

 this nuisance should be suppressed. 



Other communications from individuals and organizations in 

 all parts of the country received by the committee of the National 

 -Kssociation of Gardeners, revealed the surprising interest in this 

 movement, and indicated that the time for action is now, but 

 that it thus far has lacked co-operation to bring about unified action. 



The Sign Board Committee of the National Association of 

 Gardeners, 286 Fifth Avenue, New York City, will be glad to 

 hear from other interested sources which are ready for co-opera- 

 tion in curbing this constantly increasing nuisance! 



