ON THE TREATMENT OF THE MATURE PLANTS.
From the time that the plants become established, which is the period of their existence now about to be considered, they require to have the elements of vegetable growth duly supplied to them, in order to secure their successful developement. It is not enough to plant them in proper soil, and duly to water them, unless attention is also paid to the temperature, as well as the constituents of the atmosphere to which they are submitted; neither will attention to these latter points be sufficient to ensure success, if at the same time, the former are neglected. A soil of suitable chemical, as well as mechanical composition, a pure and wholesome atmosphere, water promptly and properly applied, and heat duly regulated, are conditions which equally require minute care and attention in their adaptation; and these being applied upon the comprehensive, and perfectly harmonious principles of nature, will leave but little to be done in the shape of expedients, which are too frequently resorted to, as the means of counterbalancing either defective or unsuitable management. The application of these agents to the cultivation of the plant under consideration, in the winter season, will form the subjects of succeeding chapters. I will here briefly direct attention to the importance of light in the growth of plants, and then devote some space to the consideration of the subject of pruning and training.
Light is most essential to the perfect and healthy developement of vegetable organization, the performance of the functions essential to the health of plants being dependent on its agency. It cannot indeed be assumed that plants will not continue to grow, unless they are supplied with an intense degree of light; but it is certain that the successful nature of their growth, their maturation, and their fructification, are dependent in no ordinary degree upon the nature and force of its action; for without it, the vital energies of animated beings are unable to maintain and perform the processes of elaboration, and assimilation, upon which their nutrition depends. The mere extension of vegetable tissue, may indeed go on, though less satisfactorily, under the almost total privation of light, but with the exception of cryptogamic vegetation, the organs of fructification are not under those circumstances, produced at all: the stem may be formed, but does not become solid: the leaves may expand, but their condition is imperfect; and it is only by means of the full and complete action of these organs in the nutrition of plants, that the developement of the floral parts is brought about: the roots may take up fluids, and these may be conveyed in the natural upward channels, and then dispersed among the stems and the leaves; but it is the action of solar light, aided indeed by the natural condition of the elements supplying heat and moisture, which alone, by a process of elaboration, can convert this fluid, once crude and undigested, into the compound organic substances, such as lignin, gum, starch, gluten, &c. which in their turn, are destined to minister to the support of the organs of reproduction. Growth, that is mere extension, may go on in proportion as heat and moisture are supplied to plants, but light is the agent to whose especial influence we owe the production of their active properties and secretions, and the perfection of their fruit.
If then light is so indispensable to the vegetable frame, how important it is that the structures which we devote to the cultivation of such plants as the Cucumber, which are naturally habituated to an eastern clime, should be so designed, as to offer the least possible obstruction to its entrance: how important, too, that the glass we employ, which in its purest state, offers considerable obstruction, by refracting the rays of light, should be as transparent and untarnished as possible, so as to admit them as perfectly as can be practicable; instead of which, it is too often disfigured by an accumulation and deposit of filth, which, to say the least, must materially diminish their force: how important, moreover, that whatever coverings it may be necessary to employ during the night to prevent the outward radiation of heat, should be speedily removed in the morning, and kept off as long as they safely may be, in order to permit the inward radiation of light. When these matters are all duly attended to, our climate, at least during the winter, still offers obstruction enough to our success, in its mists, and fogs, its long dark nights, and dismal cloudy days, and therefore wisdom would teach us, to avail ourselves of all which we can grasp, by a course of untiring assiduity, and attention to such apparently trifling matters as these.
The pruning and training of the plants, are operations, to which it will be necessary to direct attention; and in the performance of which, the circumstances which may have any influence upon them, as well as the object in view, must be taken into consideration. The plants being intended to occupy a surface of trellis-work in a line nearly parallel with the glass, it will be requisite to train their primary shoots to a sufficient length to reach from the soil to the trellis, before they are what is technically called “stopped;” this operation, by removing the central bud, or axis of developement, induces the buds which are latently formed at the nodes of the branches, to push forth and become the axes of further extension: two or three of the strongest of these lateral shoots situated towards the top of the stem, should be retained, and trained on the trellis in a direction towards the top of the house; these shoots should be placed about 18 inches from each other, and when they have reached about one-third of the length of the trellis, they also should be stopped, and thus several more lateral shoots will be produced. The uppermost strong shoot should in each case, be still trained in the same upward direction, and the others must be disposed in the most convenient form in the space between the main branches: these, that is the young lateral shoots, if they do not shew a fruit blossom at the second joint or leaf from the main branch, must be stopped, and the young shoot thus induced to push forth, will in all probability have fruit at the first leaf; if not, it must be stopped at every leaf as it extends, until fruit is observed. The upper portion of the branch after having extended about one-third further up the roof, should be submitted to the same process, and this must be again repeated until the whole of the trellis is covered.
No reference has yet been made to the treatment of those lateral branches where the young fruit are perceived: these should be permitted to grow until the blossoms have expanded; and then, after this, they should be stopped at the leaf next beyond the fruit blossoms. By permitting them to grow until the flowers have expanded, the attraction of the growing branch will continue to draw up a regular supply of nutriment, part of which will be devoted in its course, to assist the developement of the blossoms; and besides the advantage of the growing point acting thus as a sucker to draw onwards the vital juices towards the young fruit, it will act also as an outlet, to drain off what would otherwise be superabundant and dangerous to these tender organs of reproduction. After the flowers have expanded, this danger does not exist to so great an extent, the infant fruit have new and important functions to perform, which are peculiarly their own; and these call for a greater supply from the nutritive organs of the plant: the stopping of the branch therefore, is the means of throwing in this increased supply of food; but those who can most fully appreciate the delicacy of the functions performed by the plant at this stage of its developement, will most fully value the suggestion not to stop back the growing branch all at once, but to do it by successional, though not distant operations. The leaf which is directed to be left above, or beyond each fruit, will serve, both as a reservoir, to receive all the superabundant food, which may either be induced or impelled upwards; and also, as a labaratory where this food will become purified and changed by its exposure to atmospheric influence, amongst the lax tissue; and whence, an appointed portion will be returned, and devoted by a process of assimilation, to aid in the extension of the plants.
This system of pruning, with reference both to the barren and the fruitful branches, must be continued, whilst these continue in a vigorous and healthy condition; but when any symptoms of decay or of expended powers, are perceived, they should be pruned quite away, and young ones encouraged in their stead. All the pruning which has been spoken of, except the occasional removal of a main shoot, should be done at a sufficiently early period of growth, to admit of being effected by means of the thumb-nail; for like all other plants, Cucumbers are much best treated, when whatever pruning they may require, is done at that stage of growth, when the least amount of trouble and labour is required to perform it. Pruning is not under any circumstances a natural process, and when we have recourse to it in artificial cultivation, it is only an expedient, which is rendered necessary by the limited space, within which it becomes necessary to confine the extension of the plants; and since this is the case, it is far better to remove a portion of any plant, at an early period of its growth, and thus to economize its vital energies, rather than to suffer them to be expended, and the supply to become exhausted through a superfluous developement, and then to deprive it of those very organs, by the action of which, the expenditure would be again recompensed to the vital energies.