74 Gardening Under Glass 



heating and dwelling-house heating is that heat 

 is wanted in the former most during the night, 

 whereas it is during the day or early evening 

 that the home is kept warmer. Furthermore, 

 the glass garden gets most of its daytime heat 

 from the sun, and the greenhouse begins to 

 cool off very rapidly when the sun goes down. 

 It is then necessary to get the fire in good con- 

 dition, and the water or steam circulating i?i 

 time to prevent a sudden drop in the tempera- 

 ture. 



The time for opening up the greenhouse to 

 ventilate is when the temperature inside is ris- 

 ing; therefore, as a general rule, it is best to ven- 

 tilate as the sun begins to gain strength early in 

 the morning. This helps to prevent too sudden 

 a rise in temperature, which is just as bad as a 

 sudden drop. A little experience and watching 

 the thermometers will soon enable you to judge 

 easil}" just when and how much heat or ventila- 

 tion Avill be required to keep the temperature 

 running steadily, and indeed is the only way to 

 acquire the knowledge. 



By far the greater number of ornamental 

 plants and vegetables will do well with an "in- 

 termediate" temperature — i. e., night tempera- 

 ture of 45 to 55 degrees, and a day temperature 

 of 10 degrees or so higher. The "cool-house" 



