January. 1 monthly calendar. 125 



another consideration is, that in the absence of heat and 

 air, plants cannot absorb much moisture, and consequently 

 must become injured from excessive watering ; ami it may 

 be observed further, that it is not prudent to keep plants in 

 an extremely vigorous state, until the season arrives when 

 the jxternal air is soft_and salubrious ; they can then have 

 a due proportion of heat, air, and moisture at the same time. 



Perhaps the next important point to be attended to at 

 this time is, to see that the greenhouse, or room, in which 

 plants are intended to be preserved, is calculated for the 

 purpose. The room should be light and airy, and yet so 

 secure as to prevent the intrusion of external cold air, or the 

 departure of warm air in the night season. 



A Fahrenheit thermometer is indispensable in a green- 

 house, or room, where plants are kept, and the temperature 

 should be always up as nearly as possible to 40 decrees, in 

 the absence of the Sun. If the gardener retire to rest in this 

 variable climate, leaving the mercury much below 40, he 

 may expect to find his plants frozen in the morning. 



A good brick flue is better calculated for heating a small 

 greenhouse, than any other method ; because after a suffi- 

 cient fire has been made to heat the bricks thoroughly, they 

 will retain the heat through a Winter night, whereas an 

 iron stove with its metal pipes will cool as the fire gets low; 

 and expose the plants to cold, towards morning, which is 

 the time they most need protection. The heat from iron is 

 moreover too dry and parching, while an evaporation or 

 salubrious steam may be raised from bricks, by sprinkling 

 the flue occasionally, which would operate on the plants 

 similar to healthful dew drops. 



At this season of the year especially, sitting-rooms, or 

 parlours, are heated in the daytime to full 20 degrees 

 higher than what is necessary for the preserv ution of plants ; 

 consequently, as the heat decreases in the night season, 

 plants ofton get injured, unless a fire is kept up. Air must 

 be admitted to plants kept in this way, at all opportunities ; 



11* 



