VENTILATION 



2 3 



a chink of top air to the Cattleya and intermediate 

 houses on warm, sunny days during winter ; but, with 

 regard to the cool or Odontoglossum house, the treat- 

 ment is different, because during the month of September 

 the plants are repotted, and by the middle of October 

 they have become settled in the fresh compost. They 

 then commence to make new growths, and a quantity of 

 young roots. Therefore from the middle or end of 

 October the top ventilators are closed, and not opened 

 again until the warm days of spring. In each division 

 it is advisable that the atmosphere for twenty out 

 of the twenty-four hours be as regards moisture two 

 or three degrees near to saturation point. The ex- 

 ceptional four hours should be in the middle of each 

 day, when it is good practice to allow the atmosphere 

 in each division to become several degrees drier, so as 

 to give the plants an opportunity to throw off any 

 excess of superfluous moisture which, if retained, would 

 prevent sound lasting growth. The drying up of each 

 division also enables newly made growth to become 

 properly matured. It should always be remembered 

 that the majority of Orchids require sun-light, though 

 not the sun's direct rays ; but there are excep- 

 tions, as some few species require dense shade, and 

 others delight in strong sunshine. I do not admire or 

 advocate any kind of permanent shading for Orchids, 

 because in a varying climate, such as we have in 

 England during spring and autumn, the plants may not 

 require shading for several days together, and fixed 

 shading only looks ridiculous : a command over the 

 shading, therefore, is a distinct advantage to the 

 cultivator. Shading is most convenient in the form of 

 roller blinds made of light canvas netting or wooden 

 laths. The latter are extensively used on the Orchid 

 houses at Burford, and are very popular throughout the 

 country. The blinds for the intermediate and cool 



