FLORICULTURE 515 



It must be borne in mind that we can have rapid growth even in 

 feeble light, provided the necessary heat and other necessary condi- 

 tions are present. Such growth, however, is not accompanied by 

 proper nutrition and, if continued, the plant finally grows itself to 

 death. A familiar example of this is found in the case of a potato, 

 which may sprout and grow in a warm, dark cellar, and yet so long as 

 light is excluded there is little or no actual gain in weight. Light, 

 therefore, is the energy which builds up the tissues, and unless it is 

 properly regulated the plant will eventually suffer. Although light 

 is exceedingly important in the development of plants, it may act 

 injuriously if too intense. This is frequently seen in midsummer in 

 the case of plants growing out of doors, where the foliage, exposed to 

 the full rays of the sun, fade out and turn yellow, the whole plant 

 having a sick, leathery look, the leaves being smaller and the branches 

 more or less stunted. The same thing may often be seen in green- 

 houses, especially as spring advances and the light becomes strong. 

 The necessity for properly regulating light by shading is here shown, 

 but it is too often the case that proper judgment is not exercised in 

 the matter. Remembering the role of light in the growth of plants, 

 it will be seen that any attempt at lessening its intensity should be 

 made gradually, so as to give the plant an opportunity to accommo- 

 date itself to the changed conditions. (Y. B. 1895.) 



Soil Sterilization. The usual method of sterilization for green- 

 house use is to build a large bin, about 4 feet wide by 10 or 15 feet 

 long and 3 feet deep, running pipes through the bottom of the bin 

 (or through the bin a foot from the bottom) a foot apart lengthwise. 

 In a 4-foot bin there would be three pipes, with one-sixteenth inch 

 holes drilled in them on the under side, about 1 foot apart. Fill the 

 bin loosely with soil, turn in steam of about 80 pounds pressure, put 

 a few potatoes in the top of the soil, an inch or so under the surface, 

 then cover the surface with tight boards, burlap, or cloth, in order 

 to prevent escape of the steam. Usually one or two hours under 

 good pressure, if the soil is not too heavy, will cook the potatoes in 

 the top of the soil ; then one may be sure that the parasites and weed 

 seeds have been destroyed. If high-pressure steam is used the soil 

 will dry rapidly after the steam is turned off, and can be shoveled 

 out of the bin without much difficulty, especially if one side of the 

 bin is removable. 



In sterilizing soil without the use of a bin about the same process 

 is used. The pipes are laid in the ground to be sterilized in about 

 the same manner as in the bin. If it is desired to sterilize about a 

 foot of soil, the pipes should be placed under the soil about a foot, 

 with the drill holes on the under side ; the surface should then be cov- 

 ered with boards, burlap, or something to prevent the escape of the 

 steam, and the soil should, of course, first be loosened, so that the 

 steam can circulate through it. A few potatoes distributed over the 

 area will tell when the sterilization has become complete. After the 

 sterilization the pipes can be removed. It is a good plan before 

 sterilizing to mix in the manure that is to be used, as this often con- 



