48 PRACTICAL FLORICULTURE. 



then operations may be begun with safety. But for what- 

 ever purpose a hot-bed is used, in all such latitudes as 

 New York, the bed should never be made before the first 

 week in March ; great risk is run if it is made much sooner, 

 with but little advantage in earliness. Greater caution is 

 necessary in airing than with the cold frame, for with 

 the hot-bed the heat from the manure, together with the 

 sun's rays, will often run the temperature in an hour so 

 high as to destroy its whole contents, if airing at the 

 proper time has been neglected. Many a merchant doing 

 business in the city has gone home in the evening to his 

 country residence to find that his hot-bed, that had been 

 his pride in the morning, had become a scorched brown 

 mass at night for want of attention to the safety-valve 

 of " airing." In such cases, when no competent person 

 is in charge, the safest way is to tilt the sashes a few 

 inches, even before the necessity arises, rather than run the 

 risk of the sun coming out strong and destroying the 

 whole. In a southern exposure, in a sheltered place, there 

 is rarely danger in admitting air in most days in March 

 or April from 9 to 4 o'clock. But, of course, judgment 

 must be used in extreme cases. The greater heat in the 

 hot-bed necessitates watering freely whenever the surface 

 of the soil appears dry, which, in dry weather, if the heat 

 is strong, will usually be every other day. 



CHAPTER X. 



GREEN-HOUSE STRUCTURES. 



I have a peculiar pleasure in beginning to describe our 

 present modes of constructing green-houses, well knowing 

 that hundreds of my readers will turn with interest to 

 this page, in the hope that they may be enlightened on a 

 subject on whicL doubtless many of them have seriously 



