134 Principles of Plant Culture. 



too often assumes that the chief need of the plants is fre- 

 quent \\'atering, and so gives \\a\er in spoonful doses as 

 the surface soil of the pot appears dry, without oliserving 

 the state of the soil beneath. The roots of the plants in 

 the meantime may be smothering in Mater-logged soil or 

 starving from drought. If, owing to inexperience, the 

 condition of the soil cannot be determined l)y the means 

 above noted, the soil may be tij)ped out upon the hand 

 without materially disturbing the roots of the plant, by 

 leveising the pot and gently striking its rim on the edge 

 of the bench or table. The real condition can then be 

 readily determined. 



220. Copious Waterings at Considerable Intervals are 

 Preferable to frequent slight waterings. It should never 

 be forgotten that air is as essential as watej' to the ^\<i\\- 

 being of roots (90), and that the soil, however porous, 

 requires occasional ventilation (94). A considerable 

 quantity of water poured upon the surface soil of a pot- 

 ted plant, in passing downward not only thoroughly 

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

 the vitiated aii' of the soil ca\ities ahead of it and out 

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

 fresh air entei'S from above as the surplus water j)asses 

 out beneath. 



221. Rapidly-Growing Plants Require More Water and 

 are less liable to suffer from over-watering than slower- 

 growing ones. During the rest period (173), plants 

 should ))e given very little water. 



222. Some Species Require More Water than Others. 

 The native habitat of the plant is a partial guide to the 

 amount of water needed. Plants native to arid regions, 



