GREENHOUSE MANAGEMENT 427 



regard to the time when the heating apparatus must be brought 

 into use and when it must be stopped. This will depend princi- 

 pally upon the state of the weather, but as a general rule 

 artificial heating will be 'found to be necessary from the end of 

 September until the middle of May. 



In regulating temperatures the ventilators will play an im- 

 portant part, but they must be so employed as not to create a 

 sudden draught so that cold currents of air are directed straight 

 at tender plants that have been brought forward under the 

 stimulus of artificial heat. The direction of the wind must be 

 ascertained and the ventilators be opened on the leeward side of 

 the house as soon as the desired maximum temperature has been 

 reached. Avoid the simultaneous opening of ventilators that are 

 opposite to one another, since this will immediately create the 

 draught which it should be your aim to avoid. Do not be afraid of 

 admitting plenty of air on suitable days or even at night-time if 

 there be no danger of frost. The greenhouse should not be 

 transformed into an oven. The object should be to allow a free 

 circulation of air so that the plants may derive the fullest benefit 

 from a constantly changing atmosphere of an equable temperature. 



When the sun increases in power towards the middle of spring 

 the glass roof and sides of the house will require to be shaded. 

 If this be done efficiently much time will be saved in watering ; 

 the plants will be kept in a healthy condition, and the flowers will 

 retain their beauty for a longer period. If the owner of a green- 

 house can afford to purchase them, undoubtedly the best method 

 of providing shade is to have fixed to the roof adjustable roller 

 blinds which can be raised and lowered at a moment's notice in 

 accordance with the condition of the weather. Failing this 

 recourse must be had to a wash shading there are many cheap 

 and useful varieties on the market which can be applied to the 

 outside of the glass with a paint brush. The shading will be found 

 to last throughout the summer, and as autumn approaches the 

 rain will gradually thin it down until with very little effort it can 

 be removed altogether so as to leave the glass clean and trans- 

 parent for the winter, when there is all too little light and sunshine 



