TEMPERATURE 365 



Temperature. The proper temperature for vegetable 

 forcing varies greatly with the kind of vegetables. Let- 

 tuce and radishes grow best at a comparatively low tem- 

 perature, while tomatoes and cucumbers demand a high 

 temperature for their best development. Plants grown at 

 too high a temperature produce weak, spindling stems and 

 are very susceptible to disease. If the temperature is too 

 low, it seriously weakens the plants and stunts their growth. 

 The temperature at which plants may be maintained also 

 varies with the general weather conditions. During bright 

 sunny weather when plenty of ventilation may be given, 

 the temperature may run considerably higher than is de- 

 sirable under other conditions. During a prolonged 

 dark, cloudy period, it is better to maintain a lower tem- 

 perature than the plants ordinarily demand. It is always 

 the practice to maintain the temperature fifteen to twenty 

 degrees lower at night than during the day. A greater 

 difference of temperature than this is seldom desired and 

 is usually harmful. 



In controlling the temperatures of hotbeds, it is a com- 

 mon fault of the beginner to allow the bed to cool off too 

 much during the afternoon before replacing the sash. All 

 hotbeds, especially during the early spring, should be 

 covered early in the afternoon to prevent chilling the 

 plants. In ventilating them during cool weather, the 

 sash should be opened in such a manner as to prevent 

 cold drafts from striking the plants. During dark, cloudy 

 weather, hotbeds need little ventilation. 



In order to control the temperature of hotbeds, it is 

 frequently necessary to provide additional protection. 

 Mats made of rye straw are commonly used to cover the 

 sash during severe weather. Burlap mats stuffed with 



