. Plant propagation : greenhouse and nursery practice . Plant propagation. JJOTTUiM HEAT 87 The expression "ten degrees of Ijottom heat" means that the bed should l)e tliat many degrees warmer tlian the air just al)Ove the lied or in the propagating house. Usually, however, the temperature of the bed is indicated, as 60, 70, or some other degree. 133. Natural bottom heat obtained from the sun during the day is of importance at all times, but is scarcely con- sidered in greenhouse winter work, except as something to offset heat from the pipes in the propagating house. In hotbed, cold
. Plant propagation : greenhouse and nursery practice . Plant propagation. JJOTTUiM HEAT 87 The expression "ten degrees of Ijottom heat" means that the bed should l)e tliat many degrees warmer tlian the air just al)Ove the lied or in the propagating house. Usually, however, the temperature of the bed is indicated, as 60, 70, or some other degree. 133. Natural bottom heat obtained from the sun during the day is of importance at all times, but is scarcely con- sidered in greenhouse winter work, except as something to offset heat from the pipes in the propagating house. In hotbed, cold frame and other structures not usually. FIG. 75—MAKING A CONCRETE HOTBED The trenches being dug were later filled with concrete without "forms " the concrete had "set" the earth was lalien out, partly bv horse scoop partly by hand. ' heated artificially it is of great importance, especially in spring. During the day the sun penetrates the surface layer of soil, which becomes warm. During the night this heat is given off slowly and checked by mats (Fig. 74)and shutters (Fig. 48), so the fullest use may be made of it. The depth to which the soil may thus be warmed depends upon the intensity of the light, the color and other characters of the soil; for instance, dark soils absorb more rapidly than light ones. 134. Application of bottom heat may be obtained in any of the following ways: 1. Hotbeds (Fig. 80) in which manure, tan bark,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kains, M. G. (Maurice Grenville), 1868-1946. New York : Orange Judd Company
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectplantpropagation
