December io, 1890.1 



Garden and Forest. 



597 



Fig. 78. — A Fruit of Aristolochia grandiflora, natural size. — See page 596 



than that of the plants under the green. The objection urged 

 against the latter was a practical one — namely, it darkened the 

 house in the winter, when all the light possible was required 

 by the plants, while in summer it did not give sufficient shade 

 to dispense with the use of blinds. Besides this, moreover, many 

 plants also failed to grow under the green glass, although in 

 houses glazed with ordinary glass they were satisfactory. Such 

 were some Adiantums, some of the Gymnogrammes, Platyce- 

 riums and others. These plants are now in very fine health 

 in exactly the same positions as they failed in before the glass 

 was changed. Several years ago it was decided to use only 

 clear glass in repairing the other houses. I cannot just now 



lay my hands on the reasons advanced 

 by the scientists for the use of green 

 glass in preference to clear, but I believe 

 they were to the effect that the former 

 transmitted exactly the kind of light under 

 the influence of which plants grew best. 

 This light was a sickly green, which, 

 although not displeasing in its effect on 

 the appearance of the plants, gave to 

 the human countenance a peculiarly un- 

 pleasant hue. 



It has taken nearly thirty years to 

 practically demonstrate the unfitness of 

 green-tinted glass for horticulture, and 

 now these same results have been ar- 

 rived at by Professor Henslow by scien- 

 tific experiment. In a paper read at the 

 last meeting of the Linnasan Society the 

 Professor stated the results he had ob- 

 tained by experimenting on the growth of 

 plants under the influence of glass tinted 

 red, yellow, blue and green, as well as 

 under clear glass and in the open. Of 

 these the green proved not only worse 

 than the clear, but worse even than the 

 red, the yellow or the blue ! The best 

 results were obtained from plants grown 

 in the open, which is precisely what 

 every practical man knows must be the 

 case. If the temperature will admit of 

 it, then all plants are better outside than 

 when under glass. The second best 

 results were shown by plants grown un- 

 der clear glass, and here again practice 

 is at one with the Professor. Blue proved 

 worst after green, then red and then yel- 

 low. I have never seen red or blue glass 

 used in horticulture, but what is consid- 

 ered bad glass has a yellowish tint. It all 

 comes to this, then : pure light is best 

 of all for plants, and the next best is that 

 which passes through the medium that 

 least obstructs it — namely, pure clear 

 glass. Of course the intensity of the 

 light is another matter. Horticulturists 

 who use green stipple as a summer roof 

 shade for greenhouses must substitute 

 blinds or a white stipple if they desire to 

 have the best results. This is a matter 

 which deserves attention. 



Nitrate of Soda. — This bids fair to 

 become a most valuable manure in the 

 garden. I have seen it largely used both 

 this year and last for Palms, Pandanads, 

 Cycads, Aroids and other ornamental 

 leaved plants, and invariably the results 

 have been most gratifying. No manure 

 that I have seen used, not even cow ma- 

 nure, in which I have great faith, has 

 produced such immediate effect in the 

 growth, vigor and full color of foliage. 

 Mr. J. J. Willis, writing in the Gardeners' 

 Chronicle, maintains that it is a most valu- 

 able factor in the production of vegeta- 

 ble crops and fruits. He strongly recom- 

 mends it for Strawberries, Celery, Cab- 

 bages, Onions, in fact for all kitchen- 

 garden produce. But he recommends 

 it to be used in conjunction with ordi- 

 nary manures. He says : "It may be 

 stated that nitrate of soda is not regarded 

 as a substitute for other manures. Tak- 

 ing horticulture as we find it, we recom- 

 mend nitrate of soda as the cheapest and best form in which to 

 apply nitrogen to plants. To those who are using ordinary 

 stable manure we say, continue to use it, but use nitrate of soda 



in addition With few exceptions, all the fertilizers 



now generally used, in proportion to the wants of the plants, 

 contain a larger proportion of phosphoric acid, potash, etc., 

 than they do of available nitrogen. If we desire to raise maxi- 

 mum crops, therefore, we must furnish available nitrogen, 

 and the cheapest and best form in which to get this nitrogen 

 is by nitrate of soda." Nitrogen, however, is no more a substi- 

 tute for other plant food than potash is a substitute for nitrogen. 

 Kew. 7F. Watson. 



