WATER SHOULD BE WARM. 175 



soil very considerably at those seasons when plants are growing, and 

 she ceases to do so only when vegetation is exhausted — or, perhaps, 

 we ought rather to say, vegetation is exhausted when she ceases to do 

 so. It is doubtless true that this cooling process may be carried too 

 far. But that the amount of evaporation is not very considerable at 

 night, is shown by the damp state of the soil the next morning after a 

 watering. In watering at night the grojmd is soaked with moisture 

 at a time when plants are exhausted of their fluids in conseq^uence of 

 the perspiration that has been going on all day long ; the sooner that 

 loss is supplied the better ; and during the night, when perspiration 

 ceases, or very greatly diminishes, a plant is enabled to absorb by its 

 roots the water it wants, so that by the return of day it is filled with 

 fluid, and in the best possible state to resist the renewed action of the 

 sun. But when water is applied in the morning the result is very 

 different. The plant is called on to throw off moisture by its skin 

 before it has been refilled by the absorbing action of the roots; the 

 ground, too, which at night retains its water and conveys it to a plant, 

 is called on to give it up immediately to the dry, warm, and gradually 

 heating air. So that, in fact, a morning's watering cannot convey to 

 the interior of a plant anything like so much water as that of the 

 evening. 



I entertain no doubt that the great object of the cultivator should be 

 to avoid the necessity of watering ; by shading the earth, or the plants 

 themselves, or by the common operations of mulching and top dressing. 

 When watering is inevitable the tempeeatukb oe the watee is a 

 matter of great moment. Theoretically water should always be a few 

 degrees warmer than the soil; practically this cannot be always ensured. 

 All that a gardener can do is to keep his attention fixed upon the 

 principle. In summer the earth may be taken to stand at 60° while 

 cold spring water is not more than 50° ; to be beneficial the water ought 

 to be 62° at least ; if warmer so much the better. For this reason water 

 from ponds or- other places heated by the sun, should always be 

 employed when circumstances permit it. In hot-houses rain water is 

 now generally preserved in raised tanks which acquire the tempera- 

 ture of the house. By such means warm water is secured. The practice 

 has been arrived at by the teaching of experience, which shows that 

 cold water applied to the roots of hothouse or greenhouse plants; is in 

 the highest degree injurious, if not fatal. 



Among the evils of watering plants, is hardening the soil by the 

 mechanical action of water frequently dashed upon it. In this way a 

 hard crust is formed upon heavy soil, or the particles of sandy land are 

 forced together into a compact mass, which interferes with the perco- 

 lation of rain, and the free access of air to the roots. It is for this reason, 

 that the application of liquid manure by engines, or by any contrivance 

 that may cause it to fall from a height, is regarded as objectionable, and 



