Manual of American grape-growing

by U. P. Hedrick

CHAPTER XI

GRAPES UNDER GLASS

Grape-growing under glass is on the decline in America. Forty or fifty years ago the industry was a considerable one, grapes being rather commonly grown near all large cities for the market, and nearly every large estate possessing a range of glass had a grapery. But grapes are better and more cheaply grown in Europe than in America, and the advent of quick transportation permits English, French and Belgian grape-growers to send their wares to American markets more cheaply than they can be grown at home. For the present, the world war has stopped the importation of luxuries from Europe, and American gardeners ought to find the culture of grapes under glass profitable; they may expect also to be able to hold the markets for many years to come because of the destruction of Belgian houses and the shortage of labor in Europe resulting from the war.

Amateur gardeners ought never to let the culture of grapes under glass wane, since the hot-house grape is the consummation of the gardener's skill. Certainly the forcing of no other fruit yields such generous rewards. Grapes grown under glass are handsomer in appearance and better in quality than those grown out-of-doors. The clusters often attain enormous size, a weight of twenty to thirty pounds being not uncommon. The impression prevails that to grow grapes under glass, one must have expensive houses; this is not necessary, and "hot-house grapes" is a misnomer, the fruit really being grown in cold or relatively cool houses which need not be expensive. Grapes are grown under glass with greater ease and certainty than is imagined by those who form the opinion from buying the fruit at high prices in delicatessen stores. A grapery need not be an expensive luxury, and the culture of grapes under glass can be recommended to persons of moderate means who are looking for a horticultural hobby.

The Grapery

Almost any of the various modifications of greenhouses can be adapted to growing grapes. Firms constructing greenhouses usually have had experience in building graperies, and, as a rule, it will pay to have these professional builders put up the house. If the actual work is not done by a builder, it is possible to purchase plans and estimates, from which, if sufficiently detailed, local builders can work. On small places there is no doubt that the lean-to houses are most suitable, being inexpensive and furnishing protection from prevailing winds. These lean-tos should face the south and may be built against the stable, garage or other building; or better, a brick or stone wall to the north may be erected. It is possible to build a small grapery as a lean-to out of hot-house sash.

In commercial establishments and for large estates, where the grapery must be more or less ornamental, a span-roof house is rather better adapted to the grapery than a lean-to, especially if the house is not to be used for the production of grapes early in the season. On account of the exposure of the span-roof house on all sides, however, rather more skill must be exercised in growing grapes in them than in the better protected lean-to grapery. Whatever the house, it must be so constructed as to furnish an abundance of light, a requisite in which much is gained by having large-size glasses for the glazing. The glass must be of the best quality, otherwise the foliage and fruit may be blistered by the sun's rays being focused through defective spots.

Light, heat, moisture and good ventilation are all required in the grapery. Brick or stone are preferable to woodwork, as heat and moisture in the grapery are quickly destructive to wood foundations. If wood is used, only the most durable kinds should enter into the construction of the house. The under structure of masonry or of wood should be low, not higher than 18 inches or 2 feet before the superstructure of glass begins. The grapery must be well ventilated. There must be large ventilators at the peak of the house and small ones just above the foundation walls or in the foundation walls themselves. The ventilation should be such that the house can be kept free from draughts or sudden changes of temperature, as the grape under glass is a sensitive plant, and subject to mildew. Plenty of air, therefore, is an absolute necessity to the grapes, especially during the ripening of the fruit. The lower ventilators in graperies are seldom much used until the grapes begin to color, at which time the new growth, foliage and fruit are hardened, but from this time on upper and lower ventilators must be so manipulated that the houses are always generously aired.

Grapes can be forced in cold houses without the aid of artificial heat and formerly these cold graperies were very popular; but in the modern houses for growing this fruit, artificial heat is now considered a necessity, even though the heating apparatus may seldom be in use. For a finely finished product, a little heat to warm the room and dry the atmosphere may be absolutely necessary at a critical time, this often saving a house of grapes. Of heating apparatus, little need be said. Standard boilers for heating greenhouses with either steam or hot water are now to be purchased of many designs for almost every style and condition of house. Since the grapery seldom requires high heat, hot water is rather to be preferred to steam, although there is no objection to steam, especially if the grapery is a part of a large range of glass.

The border.

The border in which the vines are to be planted is the most important part of the grapery. All subsequent efforts fail if the border lacks in two imperatives, good drainage and a soil that is rich but not too rich. The grapery must be built on well-drained land or elevated above the ground to permit the construction of a properly drained border. "Border," in the sense of its being a strip or a narrow bed just inside the house, is now a misnomer, though the name undoubtedly comes from the fact that narrow beds inside the house were at one time used in which to plant vines. The border in a modern grapery now occupies all of the ground surface inside the house and may extend several feet outside the house.

Much skill is required in building the border. A good formula is: Six parts loamy turf from an old pasture; one part of well-rotted cow manure; one part of old plaster and one part of ground bone. These ingredients are composted and if the work is well done will meet very well the soil and food requirements of the grape. This formula can be varied according to soil conditions and somewhat in accordance with the variety planted. Unless natural drainage is well-nigh perfect, the border must be under-drained with tile and in any case a layer of old brick or stone is needful to make certain that the drainage is perfect. At least two feet, better three feet, of the border compost should be placed above the drainage material. In a border made as described, the grape finds ample root-run, but not too much, as in a surprisingly short time roots are found throughout all parts of this extensive border.

The care of the border is a matter of considerable moment and varies, of course, with those in charge. The usual procedure is to spade the outside border, if the border extends outside, before winter, after which it is covered with a coating of well-rotted manure, without any particular attempt having been made to keep out the frost, as a certain amount of freezing outside of the house is held to be beneficial. The inside border must be spaded just before the vines are started in the spring, having been covered previously with well-rotted manure. The time at which the vines are to be started in growth is determined by whether an early or a late crop of grapes is wanted. For an early crop, the vines must be started early in February; for a late crop, a month or even two months later suffices. So started, the first crop of grapes comes on in June or July, the later ones following in August or September.

It is related that Napoleon I, to secure saltpetre for making gunpowder, composted "filth, dead animals, urine and offal with alternate layers of turf and lime mortar," and asserted that "a nitre-bed is the very pattern of a vine-border" and that "when the materials have been turned over and over again for a year or two they are in exactly the proper state to yield either gunpowder or grapes." Napoleon's niter-bed is not now considered a good model for a grape-border, as the fruit produced in so rich a soil, though abundant, is coarse and poorly flavored, and the vines complete their own destruction by over-bearing. Gardeners hold that a grape-border may be too rich in plant-food, especially too rich in nitrogen.

Varieties

Out of the 2000 or more Vinifera grapes, probably not more than a score are grown under glass, and of these but a half dozen are commonly grown. Black varieties have the preference for indoors, especially if grown for the market, where they bring the highest prices. They are also as a rule more easily handled indoors than the white sorts. However, as we shall see, one or two white kinds are indispensable in a house of any considerable size.

Of black grapes, Black Hamburg carries the palm of merit because it is most easily grown, best stands neglect, is a heavy producer, sets its fruit well, the grapes mature early; and, in particular, it meets the requirements of the unskilled gardener better than any other grape. The clusters are not as large and the flavor not as good as that of some other sorts.

Muscat of Alexandria is the best of the white varieties. It is, however, a hard grape to handle since it requires a high temperature to bring it to perfection, is a little shy in setting fruit and the grapes are not very certain in coming to maturity; it also requires a long season. A good quality is that it may be kept long after cutting, much longer than Black Hamburg.

For an earlier white grape, Buckland Sweetwater has much to recommend it; it ripens from two to three weeks earlier than Muscat of Alexandria and is much more easily grown. It is good in quality but not of high quality. Buckland Sweetwater may be well grown in the house with Black Hamburg, whereas it is almost impossible to grow Muscat of Alexandria in the same house with Black Hamburg.

Muscat Hamburg is a cross between Black Hamburg and Muscat of Alexandria, and is an intermediate in most fruit characters between these two standard sorts. It is not, however, very generally grown, although it well deserves to be because of its large, beautiful, tapering clusters of black grapes of finest quality.

Grizzly Frontignan adds novelty to luxury in the list of indoor grapes. The fruits are mottled pink in color, deepening sometimes to a dark shade of pink, and are borne in long, slender clusters. The grapes ripen early and are unsurpassed in quality but are, all in all, rather difficult to grow.

Barbarossa and Gros Colman are the two best late black grapes, especially for those who are ambitious to grow clusters of large size with large berries. Both are very good in quality. Neither of the two is particularly easy to grow, since they require a long time to ripen; but, to offset this, both keep longer than any other sorts after ripening. Because of the large size of the berries, thinning must begin early and must be rather more severe than with other grapes. This variety is now largely grown in England for exportation to this country in early spring.

White Nice and Syrian are two white sorts which attain largest size in clusters, specimens weighing thirty pounds being not infrequent, but are coarse and poor in quality and are, therefore, hardly worth growing.

Alicante is a black sort often grown for the sake of variety, since it departs from the Vinifera type rather markedly in flavor. The grapes have very thick skins and may be kept longer than those of any other variety.

Lady Downs is another late-keeping black grape of highest quality, but difficult to grow. The bunches and berries are small in comparison with other standard sorts, characters that do not commend the variety to most gardeners.

Perhaps a dozen more sorts might be named worthy of trial in American graperies, but the list given covers the needs of commercial establishments and will meet the wants of most amateur growers.

Planting and Training

Two-year-old vines are most commonly planted. The vines are set inside the house at least a foot from the walls and four feet apart. The grapery must be built on piers with spaces of at least two feet between, and the vines are placed opposite these openings in the foundation. When planted, the vines are cut back to two or three buds, and when these start the strongest are selected for training, the others being rubbed off. The grapery must be strung with wires running lengthwise of the house at about fifteen inches from the glass. Greenhouse supply merchants furnish at a low price cast iron brackets to be fastened to the rafters to hold these wires. As the growing vines reach one wire after another, they are tied with raffia to hold them in place. Usually, young vines will reach the peak of the house by midsummer, and as soon as this goal is attained must be pinched so that the cane may thicken up and store food in the lateral buds for the coming season. When the wood is well matured, the vine is cut back to half or one-third its length, depending on the variety, laid on the ground and covered for the winter. An item of no small importance in winter care is to keep out mice, this pest being inordinately fond of grape buds, and once the buds are destroyed the vines are ruined for the coming season.

The second year's work is largely a repetition of that of the first. The vines are permitted to reach the peak of the house and are again stopped by pinching. A considerable number of laterals spring up on each side of the main vine, and these must be thinned as they develop to stand at the distance apart of the wires to which they are fastened. This is pre-supposing that the gardener has chosen the spur method of pruning, the method generally used in America and the one, all things considered, which gives best results. The selection of the laterals the second year, therefore, is a matter of much importance since spurs are to be developed from them. Care should be taken to have these spurs regularly distributed over the length of the vine. This second year, grapes must not be permitted to develop on the terminal shoots, but a few clusters may be taken from the laterals in which case the laterals are pinched two buds beyond the cluster, the pinching continuing throughout the season if the laterals persist in breaking, as they will do in most cases. At the end of the season, the terminal is shortened at least one-half, and the laterals are pinched back to a bud as close as possible to the main stem. The vines are then put down for the winter as at the close of the first season.

The work of the third season is a repetition of that of the second, with the exception that the vine is permitted to fruit throughout its whole length, although not more than one pound of fruit to a foot of main vine is permitted. The plants are now established and the only pruning in this and succeeding years is to cut the laterals at the close of each season close to the main stem, leaving strong healthy buds of which at least one, usually more, will be found close to the stem. If more than one bud starts, only the strongest is chosen, although often an extra one is needed to fill a vacancy on the opposite side. After the third or fourth season, depending somewhat on the variety, two pounds of fruit or more to the foot of the main stem can be permitted. The novice, however, is likely to permit his vines to overbear with the result that the crop is cast, or the berries rattle, or the fruit turns sour before ripening. From the beginning to the finish of the season, in this method of pruning, much pinching of laterals is required. No hard and fast rule can be laid down for this pinching, but, roughly speaking, all new growth beyond the second joint from the cluster should be pinched out as fast as it shows. With most varieties, this means that the lateral is kept about eighteen inches from the main stem. After a few years, well-developed spurs form at the base of the original laterals, and from these spurs the new wood comes year after year.

An alternative method of pruning is to permit the new canes to grow up from a bud near the ground each season. When the vine is well established, this new cane is fruited throughout its entire length, the laterals being pinched as described under the spur method. This method of pruning is known as "the long cane method." Gardeners hold that they can grow better fruit with this than with the spur method, but the difficulties are greater and the crop is not as large.

Care of the Vines

With the cultivation of all varieties indoors, more clusters set than the vines can carry. This means that a part of the clusters must be removed, an operation that depends on the variety and one that requires experience and judgment on the part of the gardener. Roughly speaking, half the clusters are taken, leaving the other half as evenly distributed on each side of the vine as possible. The time to take these clusters is also a delicate matter, since some sorts are shy in setting and the clusters must not be taken until the berries are formed and it can be seen how large the crop will be. As a rule, however, this thinning of clusters may be begun as soon as the form of the cluster can be seen.

It is very necessary also, especially with all sorts bearing large berries, that grapes be thinned in the cluster. The time to thin the cluster varies with the variety. Sorts which set fruit freely can be thinned sooner than those which are shy in setting. On the one hand, the thinning must not be done too soon as it cannot be told until the berries are of fair size which have set seed and which have not; however, if thinning is neglected too long, the berries become over-crowded and the task becomes difficult. The thinning is performed with slender scissors, and the bunches must not be touched with the hand, as touching impairs the bloom and disfigures the fruit. The clusters are turned and steadied by a small piece of pencil-shaped wood. Thinning is practiced not only to permit the berries to attain their full size but also to permit the bunches to attain as great size as possible. If too severely thinned, the clusters flatten out after maturity. This is especially the case when too many berries are taken from the center of the bunch. A large cluster of grapes is made up of several small clusters, making it necessary to tie up the upper clusters or shoulders of the bunch to permit the berries to swell without being thinned too severely. Grapes intended for long keeping require more thinning than those to be used at once after picking, since, in keeping, the berries mold or damp-off in the center of the bunch if it is too compact.

The vines in the grapery must be watered with considerable care. The amount of water to be used depends on the composition of the borders and the season of growth. If the border is loose and well-drained, the supply of water must be large; if close and retentive, but a small amount of moisture is required. Watering must not be done during the period of blossoming, since dry air is necessary for proper pollination. When the grapes begin to show color, the vines are heavily watered, after which little if any water is applied. Some gardeners mulch the vines with hay to retain the moisture in the house and keep the atmosphere dry.

Ventilating the grapery is another important detail of the season's work. Proper ventilation is difficult to secure in the early spring months when the dryness of the sun on the one hand, and cold air on the other, make it difficult to avoid draughts and regulate the temperature. Another troublesome time is when the grapes begin to color, as it is then necessary for the grapery to have air at night; but when too much air enters, there is danger from mildew. Towards the end of the season, all parts of the plant become harder in texture and the grapery may then be more generously aired. After the fruit is cut, the houses are ventilated in full so that the wood may ripen properly.

Pests

Several pests vex the gardener in growing grapes indoors. Of these, mealy-bug, red-spider, thrips and mildew are most troublesome. In a well-conducted grapery, there is never an intermission in the warfare against these pests.

Mealy-bug is usually a sign of sloth on the part of the gardener. In a grapery devoted exclusively to grape-growing, it should never be seen, but, since gardeners must often grow other plants in the grapery, mealy-bug sooner or later appears and is often hard to dislodge. It is best repelled by removing the loose bark on the trunks which harbor the pest and then washing with kerosene emulsion. When this becomes necessary, not only the vines but the rafters and all parts of the house should be sprayed with the emulsion.

Red-spider is another pest usually found in the grapery, but it thrives only in a dry atmosphere and is easily gotten rid of by syringing. As soon as red-spider appears in a house its appearance is usually known by the reddish tinge on the foliage; syringing should be kept up until the pest is disposed of, keeping the house damp in all except dull weather. Syringing is done only when plenty of air can be given and when it can be followed by sunlight so that the water remains on the vines as short a time as possible.

Thrips, another small insect, is sometimes troublesome but not often and is now easily controlled by applications of nicotine. Much care must be taken in the application of nicotine late in the season, otherwise the fruit will be injured.

The only fungous disease of the grape troublesome in the greenhouse is mildew. Mildew is usually brought on by a sudden change of temperature or by draughts in the grapery. Gardeners are of the opinion that east winds, in particular, give unfavorable conditions for mildew and prefer to open the ventilators to the west. If taken in time, mildew is easily kept in check by preventing the conditions which favor it, and by dusting the vines in dry sunshine with sulfur.

Plate XVI.—Elvira (×2/3).