This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
We doubt whether the culture of grapes in pots will ever become popular or general, as it is a costly mode of producing fruit. It is true that, under a given surface of glass, as much fruit may be raised from vines in pots as from the best established and permanent plants; but then, allowance must be made for the previous preparatory growth of the pot vines, as they require to be grown under glass for two seasons before fruiting, and during the second year they will occupy as much space as when in fruit. Two houses, therefore, are required to get one crop; and when we take into consideration the amount of time and labor required in potting, watering, and general management, it will be found that the cost of production is more than double that of border vines; and even to insure these results it is necessary to prepare a new set of fruiting plants yearly; for although it is perfectly practicable to take a crop yearly from the same plants even in pots, yet the crop is so small that it will not repay labor, and, so far as comparative economy is considered, more will be realized by fruiting young, well-prepared plants, even at the expense of a second house, the increase in the crop more than remunerating the increased expense. A thorough trial of these methods has led to this conviction.
The labor and constant watchfulness inseparable from pot culture in a climate so varied and intense in its extremes as ours, may ultimately lead us to adopt a modification of the system, combining all its advantages on much more economical principles.
The principal object attained by growing fruit trees in pots is the entire control which the cultivator has over the root growth; and with reference to forcing into fruit before the natural season, there is a very great advantage in having the soil into which the plants are growing, surrounded by the same temperature in which the branches are exposed; for when the branches of a plant are stimulated by a greater degree of heat than that influencing the roots, a species of exhaustion ensues highly detrimental to growth.
With reference to complete isolation from external influences, it is evident that the same conditions may be secured by preparing a small border inside the house, and planting out the vines with a view to permanence. In other words, plant a number of vines in a large pot, instead of placing them separately in more contracted spaces; for a border placed in this position is as much dependent upon the care of the cultivator as the pot, with the additional advantage of being better guarded against extremes either of heat, drought, or moisture. The border once prepared will require little further care, and the plants will produce good crops yearly without the constant renewal demanded by exclusive pot culture.
The accompanying sketch is introduced, the better to illustrate the above system. It will be observed that the soil in the pit a, Fig. 1, is wholly inside the house and completely isolated from the walls, so that it is surrounded by the same temperature as the branches. The soil is placed upon a stratum of drainage; oyster shells, brick, rubbish, and such like will answer well for this purpose, and insure porosity and dryness when required. The arrangements of the plants b will be understood from the ,section and ground plan, Fig. 2. The position of the heating apparatus is indicated at c. Large-sized draining tiles or flues built with brick, pigeonhole fashion, for the admission of air and heat into the soil, should be placed across the bottom of the border through the drainage, as shown at the dotted lines d. These may be placed six or eight feet apart, and left open at the ends, that the air may more effectually permeate the soil; by this means the soil will be kept at a suitable temperature, if ordinary care is exercised in the application of water. The drainage will always prevent anything like stagnation of water, but in the early stages of growth the soil should be kept rather dry, which will increase its temperature.
During active growth, water will be required more freely, and increased vigor may be imparted by manurial solutions; these applications should, however, be administered with caution, and only when the plants most require it; the majority of vine -borders are made too rich and extensive at the outset, a fruitful source of maladies, the cause being seldom suspected or recognized. Again, when the fruit approaches maturity the ripening process will be accelerated by gradually withholding water from the roots of the plants. It is well to remember that, just as we remove plants, as it were, from the hands of nature, the necessity increases for a thorough knowledge of the principles of vegetable growth, and the application of its agencies; hence we may expect to hear of failures in orchard houses; the successful production of crops from this highly artificial state of culture will at once draw a broad line of distinction between the scientific cultivator, and the mere , routine practitioner.
It will be observed that the plants are placed two feet from each other, in rows three feet apart; the object in planting thus closely at first is to secure a good crop at once, and, as occasion demands, the plants may be thinned by drawing out the least valuable. It also affords an opportunity of occasionally cutting a plant close by the surface in order to procure young, strong shoots, which are the most productive; heavier crops can be taken from the same surface, from young, vigorous canes, than from old and rigidly spur-pruned stems, according to the present prevalent system of management, and I feel convinced that this mode of renewal in graperies will ultimately become popular, as its advantages become known.
When a plant of two or three years' growth is cut down, a robust growth will follow; this shoot, if allowed to proceed unchecked, would grow to an unnecessary length, and if pruned back in winter the most mature and best fruit buds would be removed. To insure fertility near the base the shoot should be stopped by pinching out the extreme point when about two feet in length. Lateral shoots will now push, and the uppermost should be removed entirely, so as to cause the top bud to break. This treatment will cause the lower buds to fill up; the laterals should be stopped at the second or third leaf from the stem. The same course should be followed when the shoot has grown four or five feet more, keeping the laterals checked, but not entirely removed until the wood commences to ripen, when they may gradually be removed, cutting out the lowermost first. The same treatment is applicable to the preparation of fruiting plants in pots.
The quantity of fruit that can be grown by this arrangement will be much greater than could be secured by any other system, and for early forcing it combines all that is necessary for complete success. Indeed, fruit may be produced at all seasons, allowing the plants a few weeks' rest after ripening a crop, and started again to grow, thus producing more than one yearly crop. Four crops have been thus taken from the same plants in thirty-two months. How long plants would survive such treatment we have no means of ascertaining, but on the renewal mode it might be followed for an indefinite period.