20 ORCfHIDS : HOW TO GROW THEM SUCCESSFULLY. 



VENTILATION. 



This is another most important matter requiring the attention 

 of some one having a fair amount of intelligence, for Orchids 

 are plants that live, thrive, and grow robust on the air, and the 

 moisture it contains, therefore, it is absolutely necessary that they 

 should have as much air as possible without causing a draught, 

 or sudden rising or falling of the thermometer, as this would be 

 injurious. Every plant house should have ventilators to open and 

 close, both at the bottom and top of the building. Those at 

 the bottom should be in the wall, on a level with the hot-water 

 pipes, and the top ventilators should be at the highest jioint of the 

 house, while the opening and closing of these ventilators require as 

 much care as the stoking. The person in charge must be guided 

 entirely by the condition of the weather, as two successive days at 

 any season of the year may demand a difference in management. 

 One summer day may be warm and the wind calm and the houses 

 shaded from the fierce rays of the sun, and the ventilators opened 

 more or less on all sides in order to secure perfect ventilation ; the 

 following day it may still be bright, and necessary for the roller 

 blind to be let down, with cold and drjang wind blowing rather 

 strongly from, say, the west, in which case the ventilators 

 facing the west must be kept almost closed, perhaps quite so, 

 whilst those on the east side can be opened as required. A well 

 ventilated, moist growing temperature could thus be secured, but 

 not so if the ventilators were open on the windward side, with a 

 direct di-aught of cold arid air on the plants, which would cause 

 them to suffer. A careful system of ventilation should therefore 

 be observed at all periods of the year, but the autumn months 

 admit of a greater amount of au" and ventilation than at any other 

 season, as it is at this period that many Orchids have finished 

 their growth and requii-e to be "harvested," as it were, by 

 gradually reducing the amount of moistui-e both in the atmosphere 

 and at the roots, and this is easily accompHshed by ventilating 

 more freely ; but in changeable weather discretion must be used in 

 giving air, as at other seasons, bearing in mind, however, that 

 when the growth is finished they are decidedly more hardy, and 

 are capable of withstanding a lai'ger amount of air than at any 

 other period. 



During the winter months air should be admitted at all times 



