66 



HORTICULTURE FOR SCHOOLS 



FIG. 39. A simple propagating oven. 



sand moist at all times. Propagating ovens (Fig. 39) are 

 small cabinets in which bottom heat is provided by means of 

 a lantern or other heating device placed under a pan of 

 water above which is the sand containing the cuttings. Over 

 the top of the cabinet is a glass sash which can be raised 



or lowered to regulate 

 the temperature. In 

 hotbeds, bottom heat 

 is provided by fer- 

 menting manure and 

 organic matter. By 

 far the most satisfac- 

 tory arrangement for 

 rooting most cuttings 

 is the cutting-bed in 

 a greenhouse. Sand is 

 placed in the cutting- 

 bed and bottom heat is 

 furnished by steam or hot-water pipes running under the bed. 

 Ventilation is provided so that the proper air temperature 

 above the plants may be maintained. Coldframes are some- 

 times used for setting out cuttings 

 previously rooted in cutting -beds 

 provided with bottom heat. This 

 hardens the plants and prevents 

 them from becoming too tall and 

 spindling. Many hardwood cuttings, 

 such as those of the currant and 

 grape, can be grown by planting 

 them out-of-doors in well-drained 

 sandy soil (Fig. 40). In such cases 

 the heat of the sun warms the soil 

 but, of course, the heat at the bot- 

 tom of the plant is not so even as 

 that in cutting-beds in the greenhouse. Many bulbs, tubers, 



FIG. 40. Method of plant- 

 ing cuttings in a trench. 



