Book IV. ACCELERATING VEGETATION. 419 



Subsect. 2. Operations for accelerating Vegetation. 



2181. Accelerating by the form of surface consists in forming beds or banks in an east 

 and west direction, and sloping to the south, forming an angle with the horizon, the 

 maximum of which, in garden-soils, cannot exceed 45 degrees. On such beds early 

 sown crops, as radishes, peas, turnips, &c. will come much earlier, and winter standing 

 crops, as lettuce, broccoli, &c. suffer less from severe weather than those on a level sur- 

 face. The north side of such beds or ridges may be used for retarding vegetation, as leeks, 

 borecoles, &c. (2177.) 



2182. Acceleration by shelter, and exposure to the sun, is the simplest, and probably only 

 primitive mode of accelerating the vegetation of plants ; and hence one of the objects for 

 which walls and hedges are introduced in gardens. A May-duke cherry, trained against 

 a south wall, and another tree, of the same species, in the open compartment of a sheltered 

 garden, were found, by the late J. Kyle, of Moredun, near Edinburgh, on an average of 

 years, to differ a fortnight in the ripening of their fruit. In cold, damp, cloudy seasons, 

 they were nearly on a par ; but in dry, warm seasons, those on the wall were sometimes 

 fit to be gathered three weeks before the others. It may be here remarked, that though, 

 in cloudy seasons, those on the wall did not ripen before the others j yet their flavor was, 

 in such seasons, better than that of the others, probably from the comparative dryness of 

 their situation. Corn and potatoes on the south and north sides of a hill, all other circum- 

 stances being equal, ripen at about the same relative distances of time. 



2183. Accelerating by soils is effected by manures of all sorts, but especially by what 

 are called hot and stimulating manures and composts, as pigeons' dung for cucumbers, 

 blood for vines ; and, in general, as to soils, lime-rubbish, sand, and gravel, seem to have 

 the power of accelerating vegetation to a much greater degree than rich clayey or loamy 

 soils, or bog or peat earth. 



2184. Accelerating by jrrevious preparation of the pla?it is a method of considerable im- 

 portance, whether taken alone, or in connection with other modes of acceleration. It has 

 long been observed by cultivators, that early ripened crops of onions and potatoes sprout, 

 or give signs of vegetation, more early next season than late-ripened crops. The 

 same of bulbs of flowers which have been forced, which re-grow much earlier next 

 season, than those which have been grown in the open air. It was reserved to Knight, 

 however, to turn this to account in the forcing of fruit-trees, as related in a paper, ac- 

 companied as usual by what renders all the papers of that eminent horticulturist so truly 

 valuable, a rationale of the practice. 



2185. The period which any species or variety of fruit will require to attain maturity ', under any given de- 

 grees of temperature, and exposure to the influence of light in the forcing-house, will be regulated to a much 

 greater extent than is generally imagined, by the previous management and consequent state of the tree, 

 when that is first subjected to the operation of artificial heat. Every gardener knows, that when the pre- 

 vious season has been cold, and cloudy, and wet, the wood of his fruit-trees remains immature, and weak 

 abortive blossoms only are produced. The advantages of having the wood well ripened are perfectly well 

 understood ; but those which may be obtained, whenever a very early crop of fruit is required, by ripening 

 the wood very early in the preceding summer, and putting the tree into a state of repose, as soon as pos- 

 sible after its wood has become perfectly mature, do not, as far as my observation has extended, appear to 

 be at all known to gardeners ; though every one who has had in any degree the management of vines in a 

 hot-house, must have observed the different effects of the same degrees of temperature upon the same 

 plant, in October and February. In the autumn, the plants have just sunk into their winter sleep : in 

 February they are refreshed, and ready to awake again ; and whenever it is intended prematurely to ex- 

 cite their powers of life into action, the expediency of putting those powers into a state of rest, early in the 

 preceding autumn, appears obvious. (Hort. Trans. voL ii. 368.) Knight placed some vines in pots, 

 in a forcing-house, in the end of January, which ripened their fruit in the middle of July ; soon after 

 which the pots were put under the shade of a north wall in the open air. Being pruned and removed in 

 September to a south wall, they soon vegetated with much vigor, till the frost destroyed their shoots. 

 Others, which were not removed from the north wall till the following spring, when they were pruned and 

 placed against a south wall, " ripened their fruit well in the following season in a climate not nearly warm 

 enough to have ripened it at all, if the plants had previously grown in the open air." Peach-trees, some- 

 what similarly treated, unfolded their blossoms nine days earlier, " and their fruit ripened three weeks 

 earlier" than in other trees of the same varieties. (Hart. Trans, vol. ii. 372.) Pots of grapes which had 

 produced a crop previously to midsummer, were placed under a north wall till autumn : on the 12th of 

 Januarv, they were put into a stove, and ripened their fruit by the middle of April (Hort. Trans. 

 iv. 440.) 



2186. By thus inducing a state of rest in plants in pots, say vines or peaches, in 

 August, and placing them immediately in the ice-cold room till the beginning of January, 

 which is allowing four months of a winter to them, they would, in all probability, produce 

 very early crops of grapes with less forcing than would be required for such as ripen their 

 wood in October. Such pots might be placed in pine and other stoves, where a certain 

 degree of heat is kept up at any rate, and might be contrived to produce a succession of 

 fruit, in the manner practised by W. Marsland, of Stockport, by a vineyard in pots, which 

 pass in regular succession through his pine-stoves, and furnish ripe grapes the whole 

 year. A state of rest is readily induced by withholding water from plants under cover ; 

 and in the open air by covering trees, and a portion of the surface or border around or 

 before them, with canvass or oil-cloth, to throw off the autumnal and part of the winter 

 rains. 



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