386 



WATERING. 



in pots, and especially to those having suflfruticose stems, such as the pelar- 

 gonium, or to hair-rooted plants, such as heaths, and to all bulbs, it is ex- 

 tremely injurious, and often destructive of life. In the first case more water is 

 absorbed by the roots than can be decomposed by the leaves ; in the second 

 case the roots are suffocated and rotted from their delicacy ; and in the third, 

 rotting takes place from mere organic absorption ; for when the leaves of 

 bulbs decay, their roots decay also, and consequently they cannot absorb 

 Avater by their spongioles ; while absorption by the tissue still going on, the 

 vessels become surcharged and burst, and the bulb rots. Hence in the case 

 of bulbs, and such like plants in pots, the soil in which they are kept 

 should contain no more moisture than what is necessary to keep the 

 bulb, tuber, or corm, in a succulent state; but in proportion to the 

 dryness in which bulbs are kept at this season, should be the abundance 

 of the supply of water when they begin to grow. All bulbs will be found 

 to flower in their natural habitats, either during, or immediately after a 

 rainy or moist period of the year, as is the case with our wood hyacinths 

 in spring, and with the colchicum in autumn ; and much more strikingly 

 so with the bulbs and corms of Africa, which grow and flower only in 

 the rainy season. When plants are ripening their fruit, a diminished 

 supply of water increases the flavour, because at that period of growth the 

 power of decomposing it is diminished ; and if it is absorbed without 

 being decomposed, the effect will be to render the fruit watery without 

 flavour ; to crack it in some cases, to burst it in others, and in the case of 

 all keeping fruits to shorten the period for which they may be kept. The 

 same effects are produced by excess of water on bulbs, such as those of 

 the onion ; on roots and tubers, (underground stems,) such as the turnip and 

 the potato ; and even on leaves, such as those of the lettuce and the cabbage, 

 which in wet cloudy seasons are never so highly flavoured as in seasons 

 moderately moist, when succulency and flavour are combined. Water 

 should sooner be withdrawn from tender plants than from hardy ones in 

 vigorous growth, and when practicable, it should be withdrawn from all 

 plants in a growing state in time to admit of their ripening their wood. 



827. Whether plants should he watered over the leaves or only over the soil in 

 which they grow depends on the state of the plant, the temperature iji which 

 it is placed, the time of the day, the season of the year, and other circum- 

 stances. Plants in a state of vigorous growth, in a suitable temperature in 

 spring or summer, and in the afternoon or during cloudy weather, are better 

 watered over the top, in order to make certain of clearing their foliage ; but 

 late in autumn or during winter, when growth even in hothouses is or ought 

 to be slow, owing to the deficiency of light, plants should be watered chiefly 

 at their roots ; and while the most abundant supplies might be given in the 

 former case, in the latter they ought to be moderate, because the vital 

 powers of the plant are comparatively weak, and because a cold damp atmo- 

 sphere, which watering over the top at that season might produce, would, 

 by obstructing the perspiration of the leaves, occasion their decay. In general, 

 all plants, whether in the open air or in plant stractures, ought to be watered 

 over head during spring, summer, and the early part of autumn, unless they 

 are in a dormant state, or there is some specific reason why what water they 

 do receive should be given at the root. On the other hand, all plants in 

 houses not undergoing forcing, and all plants whatever in the open air during 

 the latter part of autumn, during winter, and in the early part of spring, 



