This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
There is perhaps no plant the culture of which occupies so much of the attention of horticultural writers as the Vine. The soil in which it grows, the air in which it breathes, the system of training that should be adopted, whether its roots should have artificial heat or not, and many other questions connected with its culture, are discussed from week to week in all the horticultural periodicals of the day; and, in the face of all this, there are those who doubt if any real progress is being made after all. Our own opinion is, that while as good, and probably better, Grapes were grown twenty-five years ago in isolated cases, good Grape-growing is much more common now than then; but that much has yet to be learned, every one who, like ourselves, visits many of the "odd corners" of the country, will be ready to admit. The extent to which Grape-culture has attained amongst amateurs who do not keep regular gardeners exceeds belief; and we are bound to state, as the result of our own observation, that their success will bear a very fair comparison with that of those possessing more practical skill.
In the papers we hope to give on the subject of Vine-culture, we shall confine ourselves to what we think likely to have practical value, and leave what is merely speculative to others. Our opinion is, that the day is not distant when Britain will export Grapes largely to Paris, Vienna, Berlin, St Petersburg, and other important cities on the continent of Europe, as well as America. This, we know, takes place to some extent already, but not to a thousandth part the extent it might do if proper arrangements were entered into for creating a demand by the extent and cheapness of the supply. In some of the fine dry loamy fields of the Lothians, within a mile of where we write, where coal and all needful appliances can be had cheap and near a station, where express trains can be had daily to all parts of Britain, excellent Grapes could be supplied by the ton, at such prices as would insure a rapid market for them both at home and abroad, from the beginning of December to the end of March, and leave a good profit on capital invested.
Before we close these papers, we may perhaps direct special attention to this aspect of Vine cultivation.
To facilitate reference, we shall treat the subject under its several heads, and commence with:
While Grapes may be grown in any glass structure, there are certain forms most suitable for producing given results; and if one of these is early Grapes, by which we mean Grapes ripe in March, April, and May, there is no form so suitable as the lean-to, with a due southern aspect. It should be as light as possible - that is, the astragals and rafters should be relatively narrow, and the squares of glass wide, so as to admit as much of the genial influence of the sun during the dark days of winter as possible. It is a question simply of convenience what the size of the vinery may be.
A, Wet-weather ventilator.
C, Caithness pavement.
E, Small stones.
F, Pipes for bottom-heat.
Fig. 1 gives the size and shape of one of the early vineries here; and had we built them, we would have made them both wider and loftier - not less than 15 feet wide, with a front sash of 2 feet, and the back wall 15 feet high - as we consider a large house relatively easier kept to a given temperature than a small one, while the same labour, in every respect, is incurred in connection with the latter as with the former, except in the thinning of the Grapes and a few other trifling matters, while the produce is much greater, nor is there much difference in the original cost; therefore we urge that vineries should be made a good size.
The wires to which the Vines are to be tied should not be nearer the glass than 16 inches, so that a current of air may pass between the foliage and the glass in hot weather. The leaves should never come into actual contact with the glass; for if they do, radiation from the glass during a clear cold night will freeze them, and cause them to turn yellow. There should be not less than four rows of 4-inch pipe round the front and ends of an early vinery. In addition, we recommend a steaming-tray over one of the pipes, to receive its supply of hot water from the flow-pipe, and empty itself into the return-pipe, as shown in fig. 2. This tray gives moisture to the air of the vinery in the exact ratio that the pipes give heat; for the hotter they become, the hotter the water in the tray becomes, and, consequently, it gives off more steam at the time when the hot pipes have a tendency to render it necessary. The difficulty of ventilating a vinery during severe weather in winter is well known to early forcers, and in order to meet this we have adopted the following method, shown in fig. 3: We placed a sheath of thin copper over a row of the front pipes, this sheath we connected with the external air by means of a pipe of the same material, 5 inches in diameter; the cold air presses in through this pipe into the sheath round the hot pipes, where it gets heated at once, and passes rapidly out of the upper side of the sheath, where it is pierced full of holes; this air escapes immediately under the steam-ing-tray, and being hot and dry, it absorbs what it requires of the moisture rising from the tray, and comes in contact with the leaves just in that state as to heat and moisture most conducive to their wellbeing.
The wet-weather ventilators are kept open about an inch in the dullest weather, and even during the night, to let the hot exhausted air escape; so that a constant change of air goes on even during the severest frost - a matter of no small importance if the foliage is to be kept in health and good flavour, and colour given to the fruit.
Fig 2. STEAMING-TRAY.
The water ascends into the tray from the flow-pipe at A, passes along to C, which may be 60 feet from A, and descends into the return-pipe at D.
Fig. 3. HOT-AIR VENTILATOR.
So much for the vinery. We now come to consider:
In some parts of the country, including that from which we write, the soil of any ordinary field used for agricultural purposes, if brought together to the depth of 2 feet, would grow good average crops of Grapes if a fair portion of ordinary farmyard manure were added to it, as we hope to show when we come to treat of "Grape-growing for the Million." Meantime we advise that where possible a friable calcareous loam from an old pasture should be procured - taken not more than 3 inches deep from the surface - and stacked for six months. This soil broken up, while dry, by means of a spade or fork, and mixed with half a cwt. of ground bones to the cart-load as a permanent manure, some charred earth or wood, including wood-ashes, one cart to ten of old lime-rubbish, and the same proportion of rather fresh horse-droppings, will form a first-rate border for Vines to grow and fruit in. If the locality is wet, and the loam on the verge of being what is designated clayey, let the proportion of lime-rubbish and charred clay or earth be in excess of the proportions given.
This compost should never be touched except when dry, and specially it should not be wheeled in to form the border, unless in dry, and, if possible, frosty weather.
"We have come to the conclusion that it would be well if all Vine-borders could be formed above the surface-level of the surrounding ground. If this could be done, we should hear less of sour soil, rotten roots, and shanked Grapes. As we are treating specially, at this time, of early forcing, we must come to the vexed question of bottom-heat or no bottom-heat; and we throw in our lot with those who are the advocates of bottom-heat for Vine-roots when forced early, who certainly have common sense on their side; and we advise its application from beneath the border, and not from the surface, as some are doing at the present day, believing, as we do, that its application to the surface of the border will prove of little or no practical value. Recent writers have given dismal pictures of the roasting of the roots of the Vine over or in hot chambers heated to some imaginary temperature; and no doubt it would be possible to injure the roots of Vines by such appliances as hot-water pipes in chambers under them. This is one thing; the necessity for doing so is quite another. We started an early vinery on the first of last month.
An underground thermometer showed the temperature of the border to be 42° at a depth of 18 inches; we applied a very slow fire to the boiler, that heats four rows of 4-inch pipe, buried under a stratum of brickbats and drain-tiles of various sizes, and radiating in all directions from the hot pipes. In six days the temperature rose to 60° when the surface of the border was covered with dry leaves; on the outside border these leaves were thatched with straw to throw off the rain, and they will keep the heat from radiating from the surface of the border. The water was then shut off from the bottom pipes - nor will it be applied again above once for the same period till the Grapes are ripe; yet by this gentle and short application of it, which cannot possibly injure the roots of the Vine, the temperature of the soil is raised to something like the temperature of the earth at the season when the Vine would, in its native country, be in a state of active growth. If applied in the way and to the extent here described, whether under rubble, as we have it here, or under stone pavement, as shown in the woodcut, nothing but benefit to the Vine can be the result.
If the constant firing of the bottom-heat pipes be persisted in during the greater part of the forcing season, that evil consequences will be the result is every way probable; but there is no necessity for it, especially if the surface of the border be covered with leaves as described, so as to prevent radiation. W. Thomson.
(To be continued).