Propagation by Cuttings. 



205 



Although affording no bottom heat (362 a), the cold- 

 frame may be used for propagating many plants from 

 cuttings. It is also serviceable in connection with the 

 propagating bed (368) for "hardening off" young 

 plants grown from cuttings in the latter, as well as for 

 growing many plants from seed. Set over a pit in the 

 earth, the cold-frame makes an excellent place (cold 

 pit) for wintering half-hardy plants. 



365. The Hotbed differs from the cold-frame in hav- 

 ing bottom heat (362 a), which is usually supplied by 

 the fermentation of moist vegetable material, as horse 

 manure, leaves, refuse hops or tan bark. The material 

 intended for heating, if fresh, should be thrown into 

 a pile of sufficient size to generate heat several days 

 before it is de- 

 sired for use ; 

 and unless al- 

 ready moist, it 

 should be mod- 

 erately sprin- 

 kled with water. 

 In order that 

 all the material 

 may reach the same stage of fermentation, the mass 

 should be made into a new pile after the heating starts 

 vigorously, as is indicated by vapor rising from the 

 heap, and the outer part of the mass should be placed 

 in the center of the new pile. Leaves ferment slower 

 than the other materials above named, and hence may 

 often be advantageously mixed with them to lengthen 

 the period of fermentation. 



Fig. 94. Cross-section of hotbed in pit. Tbo 

 frame is banlced up a little TTitb eartb. (After 

 Greiner.) 



