66 OPERATIONS OF GARDENING. PART I. 



indeed, serving to splash up much, more dirt upon them from 

 below than it removes from above. 



The only perfectly effectual mode of cleansing the foliage of 

 a plant is frequently (once a week, perhaps) to wash each 

 individual leaf carefully and tenderly with sponge and water 

 above and below. But upon this subject I cannot do better 

 than subjoin what is stated by Dr. Lindley : 



" It is well known to gardeners that the efficiency of leaves is much 

 promoted by their being kept clean. The great cause of the un- 

 healthiness of plants in towns is the amount of dirt which unavoid- 

 ably collects upon their surface. If such impurities are constantly 

 washed off, plants will grow as well in. cities as in country places. 

 This was found experimentally by M. Garreau, who, in the course 

 of his inquiries into the functions of the skins of plants, found 

 that soap and water had great value, plants well washed acquiring 

 a power of absorption much beyond what they possessed in their 

 unwashed condition. It was found that soap and water had a far 

 greater cleansing effect than mere water ; thus a fig-leaf which 

 had been lathered, absorbed 90 parts, while after a mere water- 

 bath it took up only half the quantity ; and a bramble, which soap 

 and water provided with 130 parts absorbed, could only consume 

 10 parts when cleansed with water alone. It was thus shown that 

 perfect cleanliness is as indispensable to plants as to animals, and 

 that dirty gardening is necessarily bad gardening. Plants breathe 

 by their leaves, and if their surface is clogged by dirt of whatever 

 kind, their breathing is impeded or prevented. Plants perspire by 

 their leaves, and dirt prevents their perspiration. Plants feed by 

 their leaves, and dirt prevents their feeding. So that breathing, 

 perspiration, and food are fatally interrupted by the accumulation 

 of foreign matters upon leaves. Let any one, after reading this, 

 cast an eye upon the state of plants in sitting-rooms, or ill-kept 

 greenhouses ; let them draw a white handkerchief over the surface 

 of such plants, or a piece of smooth white leather, if they desire to 

 know how far they are from being as clean as their nature requires. 

 Half the business of a good gardener consists in sponging and 

 washing the leaves of his plants."* 



I will only observe, in addition to this, that there is no place 

 where plants are more liable to get into a filthy condition than 

 where those of the choicest kind are usually kept, that is, in 

 the verandah of a house. This place, as well as the ground 

 immediately in front of it, is swept out every morning by the 

 * ' Theory and Practice of Horticulture,' p. 58, 2ud ed. 



