GARDENING UNDER GLASS 359 



particularly in the sunny South, should ever attempt frame culture of any 

 plants on a large scale without contriving for the water supply under a good 

 pressure ; and if this is necessary in frame culture it is still more needed when 

 we come to forcing crops in the heated greenhouse, and the ma- 

 nure heated hot-bed. 



HOTBEDS. 



The only difference in structure between the cold frame and the hotbed 

 in that the latter has an excavation made under it, for packing fresh heating 

 manure in, to get up and maintain an artificial heat. In the vicinity of the 

 larger cities hotbeds are still largely used for the Winter growing of lettuce 

 and other crops that are grown in frames in the South. There the growers 

 can depend on regular and abundant supplies of fresh horse manure, and 

 where labor is abundant the hotbed may be made a profitable method for the 

 production of these crops and the forwarding of plants for the open ground. 

 But there are few gardeners so situated, and even where the manure can be 

 had, the hotbed is not the cheapest structure in the long run for the produc- 

 tion of crops that require heat for any length of time, for it is always a dimin- 

 ishing heat, and the labor of attending to the beds is far greater than in prop- 

 erly arranged and heated greenhouses. 



In some places the gardeners have adopted fire-heated beds, to save the 

 expense and labor of manure handling and to maintain a more uniform heat. 

 These beds are constructed with an excavation below as for the manure, but 

 in place of the manure a brick flue is built through the length of the pit, and 

 above it a floor is made on which the soil is placed. A furnace at one end 

 furnishes the heat, and the hot air chamber below makes it uniform over the 

 bed. This is a poor and inconvenient imitation of a greenhouse, and the 

 same sashes that are used on the frame could be put into the shape of a double- 

 span house that would admit of head room for getting through the centre, 

 and beds or benches on each side over the flue ; and while there would be less 

 bed-space by reason of the walk, the ease of management and the fact that 

 one can work there in all weathers gives the narrow greenhouse a great ad- 

 vantage over the heated frame. It is not the intention of this work to enter 

 into the general construction of greenhouses for all purposes, but to show that 

 in the beginning of forcing, a cheap structure can be made that will answer 

 many purposes ; and which, as skill in the management of plants under arti- 

 ficial conditions increases, more elaborate structures will take their place. 

 We have treated at large on the possibilities, especially in the South, of a 

 simple sash on a frame, and we will now treat of real winter forcing. 



