16 COOL ORCHID GROWING. 



is nearly exclusively a compost of decayed vegetation. The 

 sand of course contributes nothing of a nutritive character to 

 the plant, but it keeps the compost in a porous condition. 

 While speaking of sand I would recommend that great care be 

 taken in its selection, for some of the sand obtained in lime- 

 stone districts is injurious, on account of the quantity of lime 

 which it contains. Sand should be carefully washed, and if 

 the water becomes milky it should not be employed, as in that 

 case it would do more harm than good. In potting Orchids 

 perfect cleanliness should be observed, not only as regards the 

 pots themselves, but also with respect to the drainage, or 

 " crocks," which should be carefully and thoroughly washed 

 and dried previous to their being used. For Odontoglots 

 Oncids, and Masdevallias, the pots should be at least half full, 

 or rather more than less, of crocks, a layer of very small ones 

 being placed on the top of the larger pieces, to prevent the 

 compost from being washed down, and thus preventing the 

 superfluous water from passing away freely. 



The compost itself should consist of really good and fresh 

 fibrous peat, to which may be added about one-fourth of well 

 dried horse-droppings, a little chopped living sphagnum, and 

 a few broken crocks, adding a sufficient quantity of coarse 

 well-washed river sand, ordinary white sand being generally 

 too fine for this purpose. This compost is the best that can 

 be used for the majority of cool Orchids, and if placed on good 

 drainage will be found to hold water only by absorption, as it 

 were, or by capillary attraction. This is the principle on which 

 all Orchids should be grown. There must be no obstruction 

 to the free riddance of superfluous moisture, or the compost 

 will quickly become sour, and then the roots will decay. It 

 has been repeatedly observed that cool Orchids, more especially 

 Odontoglots, \an never be supplied with too much water 

 at the root when growing, provided the compost is fref^h 



