418 SCIENCE OF GARDENING. Part II. 



which would have been devoted to their enlargement, was employed by the plant in the 

 production of blossoms, as the remaining mode which it had of propagating its species. 

 The reverse of the practice is found proportionally to increase the bulk of the tubers, and 

 has become an important point of practice in potatoe culture. The Dutch, as Darwin 

 informs us, were the first to adopt this mode in the culture of bulbous-rooted flowers. 

 In general, it may be stated, that the art of producing blossoms in perennial herbaceous 

 plants consists in permitting them to have abundance of leaves, fully exposed to the light 

 and air the preceding year, and in not cutting them over when in a state of growth, as is 

 too frequently done, but in letting them first begin to decay. By this means, healthy 

 vigorous buds and roots are prepared for exertion the following year. 



2175. General estimate of these practices. All these operations may be resorted to oc- 

 casionally as expedients, but the only permanent and general mode of inducing fruitful- 

 ness is by supplying judicious soil, exposure, and pruning. 



Sect. V. Operations for retarding or accelerating Vegetation. 



2176. To overcome difficulties is the last stage in the progress of art. After civilised 

 man has had every thing which he can desire in season, his next wish is to heighten the 

 enjoyment by consummation at extraordinary seasons. The merit here consists in con- 

 quering nature ; and in gardening this is done by cold-houses and hot-houses ; and by ex- 

 cluding or increasing the effects of the sun in the open air. The origin of these practices 

 is obviously derived from the fact, that heat is the grand stimulus to vegetation, and its 

 comparative absence, the occasion of torpor and inactivity. 



Subsect. 1. Operations for retarding Vegetation. 



2177. Retarding by the form of surface, is effected by forming beds of earth in an east 

 and west direction, sloping to the north at any angle at which the earth will stand ; here 

 salading may be sown in summer, and spinage, turnips, and such crops as shoot rapidly 

 into flower-stems during hot weather. 



2178. Retarding by shade. The simplest mode of retarding vegetation is, by keeping 

 plants constantly in comparative shade in the spring season. This is either to be done by 

 having them planted in the north side of a wall or house, or sloping bank, hill or other 

 elevation ; or by moving them there in pots ; or by placing a shade or shed over, or on 

 the south side of the vegetables to be retarded. Where the object of retarding vegetation 

 is to have the productions in perfection later in the season, the first method is generally 

 resorted to; but where vegetation is only retarded in order that it may burst forth with 

 greater vigor when the shades are removed, then either of the others is preferable. 

 Trees on an east and west espalier-rail, shaded from the sun from February to the middle 

 of May, will be later of coming into blossom, and therefore less likely to have their blos- 

 soms injured by frost. 



2179. Retarding by the cold-house, or ice-cold chamber, {figs. 169. 173.) is more particu- 

 larly applicable to plants in pots, especially fruit-trees, and might be made a practice of 

 importance. Vegetation may in this way be retarded from March to September, and the 

 plant removed at that season, by proper gradations, to a hot-house, will ripen its fruit at 

 mid-winter. It is even alleged by some gardeners, who have had experience in Russia, 

 that the vegetation of peach-trees may be so retarded an entire year ; and that afterwards, 

 when the plant is removed into spring or summer heat, in the January of the second year, 

 its vegetation is most rapid, and a crop of fruit may be ripened in March or April, with 

 very fittle exertion on the part of the gardener. The earliest potatoes are obtained from 

 tubers which have been kept two seasons ; that is, those are to be planted which have 

 been produced the season before the last ; or, the produce of summer 1821, in December 

 1822. 



2180. Retarding the ripening of fruits by excluding oxygen. M. Berard, of Montpelier, 

 in an essay on the ripening of fruits, which gained the prize of the French Academy of 

 Sciences in 1821, found that the loss of carbon is essential to the ripening of fruits; that 

 this carbon combines with the oxygen of the air, and forms carbonic acid ; and that when 

 the fruit is placed in an atmosphere deprived of oxygen, this function becomes suspended, 

 and the ripening is stopped. Hence it results, that most fruits may be preserved during 

 a certain period, by gathering them a few days before they are ripe, and placing them in 

 an atmosphere free from oxygen. The most simple process for effecting this consists in 

 placing at the bottom of a bottle, a paste formed of lime, sulphate of iron, and water ; 

 then introduce the fruit so as they may rest detached from the bottom of the bottle, and 

 from each other, and cork the bottle and cover it with cement. Peaches, plums, and 

 apricots have been kept in this way for a month ; pears and apples for three months. 

 Afterwards they will ripen perfectly by exposure to the air. (Journal R. Inst. vol. xi. 

 396.) 



