MULCHING, SHADING, AXD WATERING. 145 



tion commences in the spring, for the earth is usually suf- 

 ficiently moist ; but when they have started into growth, 

 plants should be abundantly supplied, and the quantity 

 gradually diminished as the organization becomes complete. 

 As autumn approaches, evaporation becomes less, and the 

 supply of water should be diminished, both in the quantity 

 and frequency of application. Withholding water gradually 

 from plants that are to be kept through the winter will 

 cause them to ripen their shoots, and they will be more 

 likely to survive the cold season. 



IS T o plant, at any time, should receive more moisture 

 than it can consume either by assimilation, or rejection in 

 the form of perspiration. Plants with large, broad leaves, 

 like tobacco, squashes, etc., expose more surface to the 

 light and sun, perspire freely, and hence need more water 

 than those with small, pinnate leaves, like the acacia, or 

 than succulent, or fleshy plants, a class that requires but 

 little water at any time, and is very impatient of an exces- 

 sive supply, especially in winter. 



Watering artificially is resorted to in order to maintain a 

 proper degree of humidity in the soil. This is indispen- 

 sable in hot-houses, etc., and with all plants in pots. With 

 these the protection of the glass assists in keeping the air 

 about the plants in a state of humidity. 



But in open air culture, artificial watering can never be 

 so beneficial as natural rain, and is often, indeed, a real 

 disadvantage to plants. 



Artificial watering, with all its disadvantages, must, to a 

 considerable extent, be resorted to in hot climates, or the 

 results of gardening will often be quite unsatisfactoiy. 

 In giving it, the conditions of beneficial, natural water- 

 ing should as far as possible be observed. The rains that 

 are most refreshing to plants are those of mild tempera- 

 ture and which distil gently, bringing to the roots of 

 plants not moisture only, but ammonia and carbonic acid. 

 If rain did not bring with it fertilizing matters, it would 

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