6 THE BOOK OF THE GREENHOUSE 



Glazing. — I do not propose to enter into much detail 

 as to this. Personally, I prefer the system of glazing 

 without outside putty, as it appears to be the most drip 

 proof system when the houses are well looked after as 

 regards painting. One special point must be emphasised 

 as regards glazing. This is to use only the best twenty- 

 one ounce glass. Inferior glass is a misery to the plant 

 grower, the bladders and flaws it contains acting as 

 burning glasses, and so giving much trouble. 



Shading. — Protection from the sun during the hottest 

 portion of the day is quite necessary for many plants. 

 The best way of shading a house is to use roller 

 blinds, as these may be run up or down at any time 

 according to the weather which prevails. They are also 

 useful during the winter as a slight protection from frost 

 and as a saving of fire heat. Blinds are, however, some- 

 what expensive items, for exposure to all weathers causes 

 them to perish quickly. Roller blinds made from laths 

 or narrow strips of wood are not to my mind so effective 

 as they were at one time considered to be. 



The cheapest method of shading consists in painting 

 the glass with whitening mixed with milk, or with the very 

 useful mixture known and sold as " Summer Cloud." For 

 the grower who cannot always be on the spot, something 

 that is to a certain extent permanent during the summer 

 months is necessary, and these washes provide a cheap 

 and effective shade. The objection to them is that they 

 are on in dull as well as in fine weather, but this is 

 counterbalanced by the fact that they are always on the 

 spot when needed, and this cannot always be said of 

 movable blinds however careful one may be. 



Heating.— The heating of greenhouses has gone through 

 many phases during the past half century, but I think that 

 at last we may claim to have a really good system in 

 the use of hot water for the purpose. It is a matter for 

 congratulation that the old system of using hot air flues 



