356 WATERING. 



the case of heath-soil, it becomes necessary to immerse the pot and the 

 plant in a vessel of water, so that the soil shall be six inches or a foot 

 under its surface, and thus receive a pressure sufficient to cause the 

 escape of the contained air. Another class of evils in watering plants 

 in pots arises from their not being sufficiently drained, which may 

 follow either from the operation having been improperly performed in 

 potting or shifting, or from the crevices among the drainage having 

 become choked up by the washing down of the soil. The obvious 

 manner of preventing this evil is, whenever there is the slightest 

 suspicion of over-watering, to turn the plant out of the pot, examine 

 the drainage, which will come out with the ball, and take it off and 

 replace it with fresh materials. It would be well also, in the case of 

 all plants that are likely to be over-watered, to use a larger proportion 

 of sand in the soil, and to put extra drainage in the bottom of the pot, 

 and also to introduce among the soil a considerable proportion of frag- 

 ments of freestone. 



Aquatic and marsh plants form exceptions to the treatment required 

 for plants in general ; but even these sometimes suffer through loose- 

 ness of soil when kept in pots. 



Watering with liquid-manure is of the greatest importance to plants 

 in pots and in the free earth. It provides them with food and drink 

 by one and the same means, and the rule in applying it should be 

 " Weak and often" It is most advantageous when given to plants in a 

 growing state ; because, though at other seasons a portion of it would 

 still be absorbed by the roots, yet the greater part would be washed 

 into the subsoil. 



To economize the water given to plants, more especially in the open 

 air, the surface is sometimes mulched with fibrous or littery matter, or 

 even with small stones or pebbles. Both materials retain moisture 

 and heat ; while stones or pebbles, by becoming soon dry, prevent 

 surface-damp, and reflect much heat during sunshine. The strawberry 

 is sometimes mulched with straw, and sometimes with tiles or slates, 

 or pebbles, for the double purpose of retaining moisture and keeping 

 the ripening fruit clean and the surface of the ground in the rose 

 nurseries about Paris and in different parts of England is sometimes 

 mulched with straw or littery dung, to save watering, and prevent the 

 rose-beetle from depositing her eggs in the soil. 



Stirring the Soil and Manuring. 



So much has already been said on these subjects that it is only 

 necessary here to advert to them. 



Stirring the soil is advantageous as the means of admitting air, rain, 

 and heat to the roots of plants, of promoting evaporation in moist soils, 

 and of retaining moisture in such as are dry. In the latter case the 

 dry loose soil on the surface acts as a mulching or non-conductor to 

 the soil below ; and in the former it acts by exposing a greater number 

 of moistened particles to the air than could be the case if these particles 

 were consolidated. 



