130 PRINCIPLES OF PLANT CULTURE 



sound given out by the pot will be that of a compact 

 mass instead of a more or less hollow body, as is the case 

 with a pot of well-aerated soil. To remedy the evil, 

 repot the plant in fresh soil of a proper condition of mois- 

 ture, providing abundant drainage at the bottom of the 

 pot (412). 



218. Injudicious watering is perhaps the most common 

 cause of failure in growing potted plants. The amateur 

 too often assumes that the chief need of the plants is 

 frequent watering, and so gives water in spoonful doses 

 as the surface soil of the pot appears dry, without ob- 

 serving the state of the soil beneath. The roots of the 

 plants in the meantime may be smothering in water- 

 logged soil or starving from drought. If, owing to in- 

 experience, the condition of the soil cannot be determined 

 by the means above noted, the soil may be tipped out 

 upon the hand without materially disturbing the roots of 

 the plant, by reversing the pot and gently striking its 

 rim on the edge of the bench or table. The real condi- 

 tion can then be readily determined. 



219. Watering. — Copious waterings at considerable 

 intervals are preferable to frequent slight waterings. It 

 should never be forgotten that air is as essential as water 

 to the well-being of roots (89), and that the soil, however 

 porous, requires occasional ventilation (93). A consider- 

 able quantity of water poured upon the surface soil of a 

 potted plant, in passing downward not only thoroughly 

 moistens the soil particles, but acts like a piston, forcing 

 the vitiated air of the soil cavities ahead of it and out 

 through the drainage hole at the bottom of the pot, while 

 fresh air enters from above as the surplus water passes out 

 beneath. Manure water should not often be used, as 

 there is danger in giving the plant too much food. 



