The Garden Magazine, May, 1922 



185 



placed in an adjoining depression, and with the aid of a stick 

 or pencil the clearest part of the soil extract is caused to flow 

 over and mix with the indicator. Bromthymol Blue is used as 

 a first indicator, because it at once classifies the soil. If the 

 soil be neutral, a green color develops, yellow indicates acidity, 

 and blue shows an alkaline condition. If the acid color of the 

 indicator is shown, the 

 process is repeated us- 

 ing another indicator 

 which shows its color 



changes at a 



higher de- 



TABLE OF INDICATOR COLORS 



(As seen in very dilute solution in depressions of porcelain plate.) 



Descriptive Terms Superacid | Mediacid | Subacid | Minimacid | Minimalk. j Suba'.k. | Medialk. \ Superalk 



^ — bog peat — ^ 

 ■£ — upland peat 



gree of acidity and so 

 on in succession as 

 shown by the diagram. 

 If the alkaline color ap- 

 pears another indicator 

 changing color at a 

 higher degree of alka- 

 linity is then used. 

 This is continued until 

 either an intermediate 

 color of one indicator, 

 or opposing extremes of 

 two overlapping ones, 

 are obtained. The spe- 

 cific acidity or alkalin- 

 ity can then be read off 

 from a chart or table of 

 the indicator colors. 



AS A result of the 

 t testing of many 

 hundreds of colonies of 

 wild flowers through- 

 out the Northeastern United States, Mr. Coville's conclu- 

 sions as to the requirement of members of the Heath family 

 for acid soils have been abundantly confirmed. Nearly all 

 of the 50 species of this family studied have been found to 

 be in the most flourishing condition when the soil was mediacid 

 or subacid. There were a few exceptions among the Pyrolas, 

 which thrived in minimacid or even neutral soils. In other 

 plant families some species have been shown to favor acid 

 soil and others neutral or alkaline soils. Among the native 

 Orchids, for instance, most northern species stick closely to 

 neutral soils, and most southern ones to acid soils. Similar 

 relations hold in the case of Ferns. It is hoped to publish 

 sometime a list of several hundred wild flowers, with their pref- 

 erences in this respect indicated, but sufficient data have not 

 been obtained as yet. 



The first test is made with bromthymol blue; a change to green indicates a neutral 

 soil; yellow shows acid; if remaining blue, an alkaline condition is shown. The other 

 indicators. are then used in succession upwards or downwards as the case may require 



Most of our ordinary garden plants are those favoring neu- 

 tral soils, and our ordinary methods of cultivation, fertilization, 

 and liming tend to bring soils to neutrality or even a slight de- 

 gree of alkalinity. It is, however, well worth while to develop 

 also acid soil gardens, for in these we can grow in cultivation 

 many beautiful Rhododendrons, Azaleas, Laurels, Orchids, 



etc., which will in ordi- 

 nary garden soil never 

 really thrive, and usu- 

 ally die as soon as the 

 acid soil adhering to 

 their roots when first 

 transplanted is neutral- 

 ized by the soil in which 

 they are placed. 



In making an acid 

 soil garden it is not suf- 

 ficient to dig a small 

 hole and place in it the 

 balls of earth adhering 

 to the roots of the plants 

 being introduced, for 

 moles, earthworms, 

 beetles, etc. will soon mix 

 the alkaline garden soil 

 with the small mass of 

 acid soil, and this to- 

 gether with the circula- 

 tion of underground wa- 

 ters, will soon lead to the 

 neutralization of the 

 acidity and the death of 

 the plants. The bed must 

 be dug out to a depth of 

 two feet or more, and its area made as large as practicable; it 

 should then be lined all around with acid peat, decaying wood, 

 sphagnum moss, or similar materials, to prevent the introduc- 

 tion of lime by circulating ground water. The filling should 

 consist of a mixture of neutral sand and the same acid humus- 

 yielding materials, pine needles, fresh oak leaves, etc. The bed 

 should not be watered, moreover, with the usual city water, for 

 in most places this is likely to be alkaline. Instead, rain water 

 should be collected in a barrel, made acid by throwing in some 

 bits of pine bark, and used when required in dry weather. In 

 such a bed one can grow successfully the many beautiful plants 

 of the Heath family; Pink Slipper-orchid and Fringed Orchis; 

 Clintonia or Wood-lily; painted Trillium; Bunchberry; Box- 

 huckleberry; Twin-flower, and their various companions, so 

 often seen in woodlands, but rarely in gardens. 



^ — leaf mold — ^ ^ — "alkali" soil- 



^ — limestone soil — ^ 



SOME SUMMER ANTICIPATIONS 



"DOOK Week" in Chicago was a sort of prolonged and glorified garden party which offered the always welcome opportunity of per- 



lJ sonal chat with our subscribers, and we are just back at the desk in stimulated mood full of pleasant plans for the coming months. 



Of prime interest to our people is the privilege of finding in an early issue the Latest Message of William Robinson, dean of 

 gardeners, familiarly known to us all through his "English Flower Garden." Rather a pretty compliment is paid to the perceptiveness 

 and receptiveness of his American audience by Mr. Robinson in giving them directly through the pages of The Garden Magazine this 

 series of articles containing the crystalization of his matured thought ripened and enriched by many years' experience. Even a cursory 

 study of " Home Landscapes," Mr. Robinson's latest book, reveals a fundamental similarity of aim with that of Dr. Sargent (examples 

 of whose work may be found on pages 167, 193 of this number). Is it not significant when these two most constructive of modern- 

 day gardeners on opposite sides of an ocean express themselves in like ways? Both emphasize, moreover, the satisfying character of 

 the woody plant — trees and shrubs — as the basic "stuff" upon which a good garden is builded. 



Iris Time in June again! And for the lover of Iris fresh light on the Cultural Handling of the Bearded Group with a series of 

 carefully made photographs by Mr. A. C. Amy of the University of Minnesota. The fascinating yet irritating family of Mediter- 

 ranean Iris is ably championed by S. Stillman Berry; and, in response to many requests, we hope to reprint in substance at least a 

 very successful account of Irises for a Succession of Bloom. 



There are a number of other things we would like to tell about— such as the History of Ironwork and its Present-Day Gar- 

 den Uses by Mr. Arthur W. Colton, already known to our readers through his able series "The House That Was Built for a Garden," 

 and more widely known as essayist and poet— but it is here possible only to touch on one or two "high spots" and leave the rest to 

 your imagination, with the passing assurance, however, that you will find something you want on a number of subjects besides. Let 

 past performances be the guarantee for the future! 



