1540 



ROCK GARDENS 



the arrangement of our roek gardens. Every precau- 

 tion ^Ijould be tuken To secure the full advjinlage of 

 rainfall and any natural \v:tter su]M'ly. ^lU'l there .sliouhl 

 also be :l libi^ral and <-i.]t^t;ait artiHrial wat.T sn|i|i]y. It 

 must bf kept in mind, teo, tliat at low (dpvati(ins tho 

 long, liot summers do not allow tlip pn-ind of rest that 

 suf'li plants reqiiire. This condition must be met by de- 

 vices, methods and loratious that will redard thr growlli 

 in sijring, cheek it at an early period in autumn, and 

 keep the plaiirs fully dormant in winter, such as 

 shade, mulching, and, in the case of pari icularly difli- 

 cult pbiTirs, the protection of frames. It is rsv;,-nti;d 

 that conditions be provided tliat will onabh' the rnots to 

 extend for a lontj: distance, often many trot, in narrow 

 crevices and pockets betwem rorks to d^-iiths ^Yber(' 

 there is a uiiif<irm teminTature and uniform moisture 

 supplied by moving water, f^r fj-rquour freoziug and 



213S. A pocket in the rocks. 



thawing and stagnant water are fatal. These cavi- 

 ties should he tilled ^vith such ior.su uiaterial as frag- 

 ments of rock mixed with decayed vegetable matter, 

 without manure, and arranged to provide for the free 

 Tiassau^i:- ')f hair-like r<.)ots. for yterfect drainage and the 

 free aceess of air. To prc^vidi:- these unusual conditions 

 ou the average private jdaee in a large way would be so 

 dilhcult and so expensive ilint it is not to be recont- 

 mended. A small collection c<imprising a few easily cul- 

 tivated alpines and the similar rock plants referred to in 

 a later paragra])ii may, however, be successfully grown 

 on reconstructed stone walls, on ledges, in small rock 

 gardens and in the o]ien liorders of almost any country or' 

 city place. Persons v.ho desire to cultivate a large col- 

 lection of true alpinu.s should seek a situation where 

 favorable natural or existin^i" conditions can lie taken 

 advantage of. Such locations are liktdy to be found at 

 the seashore and in roeky and hflly regions — such re- 

 gions, for examjile, as are seh-cted by many peojjle for 

 summer homes. A led-;e, a jiatural mass of boulders 

 or an abandone("I quarry will td'ten j.rovide them. 

 Pockets and crevi^-es of ledges can be .di-ared of unsuit- 

 able material, and if they are not deep enough to hold 

 moisture and have an equable temperature their depth 

 may be increased by the judicious use of wedges, bars 

 and explosives. Boulders can be an-anu:ed in such a 

 manner as to secure suitaide deeji pnckrts and crevices 

 of soil, springs cnii be diverted 1o sui>ply a constant 

 flow of water, undecLn-nund )>i])i's can he carried from 

 an artificial sou)-ce of su])idy to vnriuus jniiuts where 

 conditions require them. Idewever favorable the condi- 

 tions are, it will be found that much can lie done to 

 advantage in dilferent localities to nu-et the special re- 

 quirements of different groujis of plants. In sn(di work. 

 howe\er. it sluMild bekept eeiisTantly in mind iliat liiere 

 an; plants thiit will grow in all sorts ot snrrouudini^s. 

 and that it will often be mihdi la 11 ci- to seek sueh as ar('' 



ROCK GARDENS 



adapted to existing conditions than to go to the ex- 

 pense of radically modifying such arrangements. 



If an artificial rockery is to be construeted, it should 

 be borne in mind that it is not for the purpose of dis- 

 idaving a collection of curious rocks fantastically ar- 

 ranged, hut to provide a place for growing a class of 

 plants that cannot be as well grown elsewhere. It would 

 be l.iettcr never to think of securing mountain, valley 

 ami rock elTects in the disposition of the material to bt; 

 used, but only to think of providing mauj' varied con- 

 ditions and situatiojjs as regards exposure to sun and 

 shade, depth of pockets and crevices, the character and 

 depth of soils, subterranean and surface water supply, 

 and whether it be permanent or nuctuating. In select- 

 ijig and arranging the rocks freshly broken raw faces 

 sliouid not be exposed, but rather such faces as are 

 already covered with a growth of lichens for sunny 

 places and with mosses for shady spots. 

 To take full advantage of surface water, 

 pockets and crevices should have a decid- 

 edly downward direction from the exposed 

 ^ '~t^^ surface and not be sheltered by over- 



'''^ ^ hanging rock. That this does not a])ply 

 "" ' in all cases, those who are familiar with 



the habitats of rock -plants know full 

 well. The natural habitat of Pelkea gra- 

 cilis in the upper Mississippi bluffs is in 

 horizontal crevices well back from the 

 edge of the overhanging rock, where it is 

 absolutely protected from all surface 

 water. It finds sufficient moisture in the 

 horizontal seams. Pelhva airopnrptirea 

 will grow in narrow ci'acks and small 

 pockets on the face of dry limestone 

 boulders where there can be no pjossible 

 internal supply of moisture. These in- 

 stances go to show that the general prin- 

 ciples that will apply to such plants as a 

 class will not apply to all S[}ecies, and it 

 simp>ly gives empihasis to the importance 

 of trying a x^lant under all sorts of condi- 

 tions before assuming that it can not be 

 grown. The writer remembers well an at- 

 tempt to grow that most exquisite alpine 

 flower, GeiiliiDiK verua, in the open border 

 on a little pile of rocks to give it suitable 

 drainage. It was transplanted a number of times to 

 places wliere its environment appeared to be about the 

 same, and hnally a situation was secured, where, instead 

 of barely holding its own, it increased and produced a 

 number of its great deep blue tiower-cups. 



The importance of protection from drj'ing and cold 

 winds and of securing shade in many situations must 

 not be overlooked. Sometimes advantage may be taken 

 of an existing deciduous or evergreen tree or shrub 

 growth, or rapid-growing varieties can be planted to 

 make a screen. While shelters of this character are of 

 value about the outer limits of a rock garden, they can 

 hardly l)e used for separating its smaller compartments. 

 For this purpose slow-growing, dense-foli^aged ever- 

 greens with a restricted root range are best. This 

 wouhl include the Yuccas, a few of the dwarf forms of 

 Thuya, .Tuuiiierus, Picea. Retinis])ora and practically all 

 the broail-leaved evergreens. Tlie latter, especially the 

 Rhododendrons (of wliieh B]i<i<l<Hh.'U(lron waxiniimt can 

 lie secured in large plants at low cost), are particularly 

 useful owing to their habit of growth, restricted root 

 area., and the facility with which they can be moved 

 from place to place as desired. As these sbelter-belts 

 and groups form the background and setting of the rock 

 garden and are the dominating landscape feature in 

 views from a distance, their composition and disposition 

 is a matter of much importance. The dis[iosition must 

 be governed, however, by the general arrangement of 

 the grounds, but in this arrangennuit an agreealdy 

 varied sky-line and composition of plant forms and of 

 shades of green should be sought for. In the composi- 

 tion of the background, and in the planting of the rock 

 garden as well, a decided clun*acter should be given to 

 the whole and to each dislinct compartment by using 

 ^onn- few el'Ce(qive plants in (]uantity ratherthan a great 

 mnnlier of varieti<-s in small quantities. Variegated 

 and distorted ,i;arden freaks should be excluded, for 



