Sub-Irrigation 



lies of plants, grown under approximately the same conditions. In some 

 mstances the product of the sub-irrigation bench has been nearly one-third 

 greater in money value than was secured from the surface-watered bench, 

 from the same variety grown in the same soil and in the same house ; that is 

 to say, as near as it is possible to obtain the same conditions. 



I have not been able to determine that plants grown upon sub-irrigation 

 benches are more exempt from disease and insects than those grown upon 

 surface-watered benches, excepting, as before stated, that the plants may 

 be in a more vigorous growing condition, and thereby able to withstand 

 and throw off the attacks of insects and the various plant diseases. A better 

 average growth will usually be secured from the sub-irrigation bench where 

 it is properly handled, for the reason that underneath the soil there is always 

 a mass of moist brick, which gives off the water very slowdy to the soil 

 W'hen the bench passes to the dry side. This, of course, affords a more 

 constant and even supply of moisture for the plant's use, and renders impos- 

 sible the drying out of the bench soil from underneath, which sometimes 

 occurs in surface-watered benches, especially in very cold weather, when 

 high firing is necessary. One of the principal advantages that seems to 

 arise from the use of sub-irrigation benches is that the mass of cement and 

 tile at the bottom of the bench absorbs the heat from the steam pipes and 

 passes it gradually upward through the soil, so that where high firing 

 occurs this shield of brick or tile between the hot steam pipes and the roots 

 of the plants is a decided benefit. Again, when steam is turned off, these 

 tiles remain warm, and continue to give off a moderate heat to the soil ; and, 

 in my opinion, this even, moist condition at the bottom of the bench, and 

 steady, modified heating of the soil, tend to a more regular and stronger 

 growth of the plants, as well as a greater production of flowers. This is 

 shown by the fact that plants upon sub-irrigation benches usually produce 

 flowers with stems three to four inches longer, and from 20 to 25 per cent, 

 stronger, than those obtained from plants growing on surface-watered 

 benches. 



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