FLORICULTURE 521 



If desired, the organic-manure solutions may be discarded and 

 only chemical fertilizers used. Manure may also be left out of the 

 soil and chemical fertilizers substituted. Voorhees recommends for 

 forcing house crops in general when a good loam of reasonable fer- 

 tility is used : One-half pound nitrate of soda, 1 pound acid phos- 

 phate, 1 pound ground bone, one-half pound muriate of potash, 

 This is to be thoroughly mixed in the soil for each 100 square feet of 

 bench at the time of filling, with subsequent feeding, as in the case 

 of regular compost. He recommends for roses and other flowering 

 plants where phosphates are especially desirable, 4 parts ground bone 

 and 1 part muriate of potash, at the rate of 2 pounds of the mixture 

 per 100 square feet of area, well worked into the soil previous to set- 

 ting the plants. Later feeding may be followed as in regular compost 

 soils. (Reprint 1910, Y. B. 1902.) 



Irrigation for the Greenhouse. From the very nature of the 

 case, plants grown under glass can not obtain a supply of water 

 either from the clouds above or from the underlying soil, and if 

 they are to maintain their growth it must be applied artificially. 

 The common method of applying it through a hose or from a water- 

 ing pot requires a man of experience and good judgment, as it is de- 

 sirable to apply enough to moisten the soil without saturating it. Sur- 

 face watering at the best packs the soil, thus preventing its proper 

 aeration, promotes the development of slime and mosses upon its 

 surface, and, particularly during the cloudy days of winter, keeps 

 the surface of the soil in a damp condition, although the roots may 

 be suffering from lack of water. In many cases, too, the water lodges 

 in the axils of the lower leaves of the plants, and by keeping them 

 moist promotes the development of the spores of parasitic fungi. 



To lessen the labor of watering greenhouses, various sprinkling 

 arrangements have been tried. Some of these consist of sprinklers 

 that can be moved from point to point in the houses, while others are 

 arranged at intervals upon pipes so as to water considerable areas at 

 one time. While some of these arrangements may be labor savers, 

 they have all of the disadvantages of surface watering ; while the fact 

 that all parts of the house may not require the same amount of water, 

 and that unless carefully watched a surplus of water is likely to be 

 applied, renders them impracticable. 



Greenhouse Subirrigation. Various methods of applying the 

 water below the surface have been tried and for many crops have 

 shown decided advantages over surface watering. The first attempt 

 at greenhouse subirrigation was made at the Ohio Experiment Sta- 

 tion, in 1890-91, with the hope of preventing lettuce rot. The result 

 upon the growth of the plants was so marked that it was repeated 

 upon a larger scale and with a variety of plants. Similar experiments 

 have been tried and the results published by the West Virginia and 

 the Michigan Experiment Stations. 



While applicable to pot plants, it is generally used for those 

 planted out in beds. These may be raised benches made of wood, 

 or of iron supports with tile or slate bottoms, or they may^ be what 

 are termed solid beds, resting directly upon the soil. In either case 



