WATERING. 



387 



should be Avatei-ed only at the root. Watering over the top should in general 

 never be performed during bright sunshine ; yet there are various plants 

 with which this may be done with impunity, such as all the grasses ; and in 

 the royal kitchen-garden at Versailles the Alpine strawberry is watered 

 over head during bright sunshine throughout the whole summer, without 

 any inconvenience being found to result to the plants. (G. M.^ vol. xvii., 

 p. 387.) Watering during summer should in general be performed in 

 the afternoon or evening, because at these periods less will be carried off by 

 evaporation than during the day ; while during winter and spring, watering 

 ought to take place during the morning, that during the day the surface of 

 the ground may be warmed and dried by evaporation and infiltration. In 

 general, watering over the top is only necessary with plants in leaf; but 

 plants, and especially trees, which have been newly transplanted, may be 

 advantageously watered over the top to diminish evaporation from the bark, 

 which without being so moistened might (786) lessen the amount of sap 

 returned by it to the root. 



828. Watering plants in pots requires much more consideration on the 

 part of the waterer than watering in free soil. When the plant is in a 

 dormant state, though it must not receive so much water as to excite it into 

 growth, or distend its parts more than is necessary to prepare it for active 

 vegetation, yet still it must receive as much as to prevent the soil from being 

 so dry as to extract moisture from the roots. As a test for this being the case, 

 the soil in the pot, when opened or stirred up on the surface, ought to have 

 a fresh appearance, neither moist nor dry ; nearly dry in the case of bulbs 

 and tubers, and nearly moist in the case of dormant deciduous plants. 

 Another difficulty in watering plants in pots is to ascertain that the wtiter 

 given has penetrated the whole of the soil in the pot. The ball or mass of 

 soil is frequently so filled with roots, or from its nature and treatment so 

 compact (742), as not to be readily peraieable by water, which in that case, 

 after merely moistening the surface, escapes between the ball and the pot ; 

 while the operator, seeing the water escaping from the bottom of the pot, 

 concludes that the mass of soil has been thoroughly penetrated and saturated 

 by it. Many greenhouse plants, particularly oranges, camellias, and heaths, 

 are killed by this mode of deceptive watering, which may be traced to this 

 <;ause, viz., that when once soil is thoroughly dried so as to become like 

 dust, it loses the power of capillary attraction, and resists the entrance of 

 Water unless accompanied by extraordinary pressure. Soil containing peat- 

 earth is peculiarly liable to this kind of dryness when watering in proper 

 time has been neglected ; and hence the value of Mr. McNab's mode (749) 

 of mixing with such soil pieces of broken freestone. To ascertain when the 

 water has penetrated the mass of soil in a pot, it is common to thrust into it, 

 not far fi-om the stem of the plant, a round pointed stick, and to make sure 

 of moistening the interior, to pour in water in the hole so formed. In 

 loamy soils, or soils containing a large proportion of sand, this mode will 

 suffice for saturating the ball ; but in 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 sis 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 arise either from the operation having been improperly per- 

 formed in potting or shifting, or from the crevices among the drainage 



