In addition to the fire heat, a steam apparatus has been lately erected, and the tubes conducted round the houses on the tops of the flues (fig. 15. d, e); this is found to give a great command of heat, and also to admit of filling the house with vapour at pleasure. The height of the house from the ground to the top of the back wall, is only nine feet (fig. 17.); the rafters of the roof are placed about four feet apart, centre from centre; or about twenty-four sashes are given to every hundred feet; the front sashes (a), are only eighteen inches high, and slide past each other; the middle end sash (b), also slides; the sill of the door (c), and the back path, or border, are on a level with the outer surface of the ground, to admit the easy wheeling in of tan, &c.; the front border (d), is raised considerably above it, on account of the wet bottom; the back sheds are low and neat, and the furnaces sunk three feet below the surface (fig. 16, h h) to give them a better draught; and this also serves to drain the back border.

The houses are placed in pairs, the furnaces for general use at the extreme ends of the range, and the auxiliary ones in the middle, where the steam-boiler is also placed, but worked by a fire apart.

On the whole, no plan of Pine-stove that has yet appeared, is more simple, neat, economical, and complete than this; the only fault we have to them, is, that owing to the great thickness of wood employed on the bars of the sashes, they are rather dark and gloomy within; but this might easily be remedied by the substitution of light iron rafters, with wooden framed sashes sliding in them, but the bars of the sashes formed of iron. It is true, gloomy as these houses are, the Pines thrive in them as well as can be wished, but probably by having more light, they might thrive, so as to surpass all expectation.

Soil. Good yellow loam, with a third of rotten dung, and some road grit to serve as sand. This is well mixed together, and passed through a wide screen, and the pots are well drained with three or four pieces of potsherd.

General management. This differs in little or nothing from that of Mr. Andrews; and only from that of Mr. Baldwin in the crowns and suckers being struck in pots, instead of the bark, as is Mr. Baldwin’s practice. Supposing the crowns and suckers potted in September, they are not disturbed till the following March; such as are very forward, are shifted at once into large pots, and will show fruit in the course of that autumn, or within the year, and ripen their fruit in November or December, very desirable periods for the royal table, equally expeditious, as in Mr. Baldwin’s mode, and more so than in Cuba or Jamaica. The plants which are in a less forward state are disrooted entirely, put into pots according to their sizes, nursed all the summer in the pits, and moved to the larger houses in autumn, where they show fruit at various periods, during the winter, and in the following season; thus ripening their fruit at different periods, from eighteen months to two and a half years, from the time they were taken from the parent plants. The pots in which these plants are fruited, seldom exceed twelve inches in diameter.

Insects. Various modes of getting rid of these was attempted both at Kew and Kensington; that which was finally successful was steeping for two or three hours in strong tobacco-water, as recommended by Miller; then washing in pure water two or three times—drying, planting, shading, and applying a brisk bottom heat, a moist atmosphere, and giving a little air. This recovered the plants, and future regimen continued them in the vigorous state of health in which they now are.

Fruit produced. The object, and it is most successfully attained, is to have handsome Pines on the royal table every day in the year; they cannot, of course, be very high-flavoured in the winter and spring months; but appearance, in some cases, is every thing—they look well, the golden hue of the Apple, mimic grandeur of the crown, and the presence of such a rare fruit at an uncommon season, accords well with the pomp and splendour of a royal table. As to flavor, indeed, by the time the desert appears on great occasions, the palate is generally seasoned with wine, and a few drops of alcohol are already transferred to the ventricles of the brain; when that is the case, every fruit has just what flavor it ought to have; for the fine phrensy of a warmed imagination knows no degree of merit but the superlative.

CHAP. V.
IMPROVEMENTS RECENTLY ATTEMPTED IN THE CULTURE OF THE PINE APPLE.

The Pine Apple has never been so generally cultivated in this country as it might have been, from an idea that its culture is attended with more difficulty and expense than that of all other fruits; and, also, from the circumstance of the greater number of gardeners being ignorant of its cultivation. With respect to the difficulty of cultivating this fruit, every gardener, who knows any thing about it, knows it is much easier grown and fruited than the cucumber early in spring, or the melon at any period of the year. In short, with the single difference of requiring an artificial temperature, it is as easy, or easier to grow than a common cabbage:—it is not nearly so liable to insects as that plant is in dry seasons; and of two plantations, the one of crowns or suckers of Pines, and the other of seedling cabbages, we may venture to assert, that more of the former will perfect their fruit than those of the latter will perfect their loaf or head.

With respect to the expense of cultivating the Pine Apple, it must be acknowledged that it is greater than that required to cultivate any other fruit; from the length of time requisite to bring it to perfection; the keeping up a high temperature during the winter months, and the unremitting attention required throughout the year. Another source of expense, and in some cases of difficulty, has been the procuring of tan, or other materials, to supply a bottom heat; and the last one that may be mentioned is, that gardeners who undertake to cultivate the Pine Apple, generally are paid a higher remuneration than those who confine themselves to the other fruits.

These circumstances have lately induced some amateurs, and also some practical gardeners, to devise means of simplifying the culture of the Pine Apple, and lessening the expenses attending it. The principal amateurs are T. A. Knight, Esq. the President of the Horticultural Society, and Peter Marsland, Esq. of Woodbank, near Stockport; the principal practical gardeners are Mr. Gunter, of Earlscourt, Mr. Hay, a Horticultural architect in Edinburgh, and some others, who have made less extensive trials.

Sect. I.
Of the improvements in the culture of the Pine Apple, proposed by T. A. Knight, Esq. F.R.S. P.H.S., of Downton-Castle, Herefordshire.

Mr. Knight’s improvements consist chiefly in the disuse of bottom heat, and in the application of a much higher temperature during sunshine at all seasons, but especially in the summer season, and a much lower temperature during winter, and during the night, at all times, than is generally adopted by gardeners.

Mr. Knight had no experience in the culture of the Pine Apple till the year 1819. In that year, he informs us (in a paper published in the third volume of the Horticultural Transactions) that he tried the effect of a very high temperature during the day, in bright weather, and of comparatively low temperature during the night, and in cloudy weather. A fire of sufficient power only to preserve the house in a temperature of about 70° during summer, was employed; but no air was given, nor its escape facilitated, till the thermometer, perfectly shaded, indicated a temperature of 95°, and then only two of the upper lights, one at each end, were let down about four inches. The heat of the house was, consequently, sometimes raised to 110°, during the middle of bright days, and it generally varied in such days from 90° to 105°, declining during the evening to about 80°, and to 70° in the night. Late in the evening of every bright and hot day, the plants were copiously sprinkled with water, nearly of the temperature of the external air. The melon, water-melon, Guernsey lily, fig-tree, nectarine, orange and lemon, mango, Avocado-pear, Mammee-tree, and several other plants, part of them natives of temperate climates, grew in this hot-house so managed “through the whole summer, without any one of them being etiolated, or any way injured, by the very high temperature to which they were occasionally subjected; and from these and other facts,” Mr. Knight continues, “which have come within my observation, I think myself justified in inferring, that in almost all cases in which the object of the cultivator is to promote the rapid and vigorous growth of his plants, very high temperature, provided it be accompanied by bright sunshine, may be employed with great advantage; but it is necessary that the glass of his house should be of good quality, and that his plants be placed near it, and be abundantly supplied with sand and water.” In the above case liquid-manure was employed.

It is added, “My house contains a few Pine Apple plants, in the treatment of which I have deviated somewhat widely from the common practice; and I think with the best effects, for their growth has been exceedingly rapid, and a great many gardeners, who have come to see them, have unanimously pronounced them more perfect than any which they had previously seen. But many of the gardeners think that my mode of management will not succeed in winter, and that my plants will become unhealthy, if they do not perish in that season; and as some of them have had much experience, and I very little, I wish, at present, to decline saying more relative to the culture of that plant.” Hort. Trans. iii. 465.

The above information, the result of Mr. Knight’s experiments in 1819, was communicated to the Horticultural Society in the autumn of that year. On the 7th of March following, a paper was read to the Society on the same plants, of which the following is a transcript:

Of those gardeners who doubted whether the plants would stand the winter, it is stated, “The same gardeners have since frequently visited my hot-house, and they have unanimously pronounced my plants more healthy and vigorous than any they had previously seen: and they are all, I have good reason to believe, zealous converts to my mode of culture.

“I had long been much dissatisfied with the manner in which the Pine Apple plant is usually treated, and very much disposed to believe the bark-bed, as Mr. Kent has stated, (Hort. Trans. iii. 288.) ‘worse than useless,’ subsequent to the emission of roots by the crowns or suckers. I therefore resolved to make a few experiments upon the culture of that plant; but as I had not at that period, (the beginning of October,) any hot-house, I deferred obtaining plants till the following spring. My hot-house was not completed till the second week in June (1819,) at which period I began my experiment upon nine plants, which had been but very ill preserved through the preceding winter by the gardener of one of my friends, with very inadequate means, and in a very inhospitable climate. These, at this period, were not larger plants than some which I have subsequently raised from small crowns, (three having been afforded by one fruit,) planted in the middle of August, were in the end of December last; but they are now beginning to blossom, and in the opinion of every gardener who has seen them, promise fruit of great size and perfection. They are all of the variety known by the name of Ripley’s Queen Pine.

“Upon the introduction of my plants into the hot-house, the mode of management, which it is the object of the present communication to describe, commenced. They were put into pots of somewhat more than a foot in diameter, in a compost made of thin, green turf, recently taken from a river-side, chopped very small, and pressed closely, whilst wet, into the pots; a circular piece of the same material, of about an inch in thickness, having been inverted, unbroken, to occupy the bottom of each pot. This substance, so applied, I have always found to afford the most efficient means for draining off superfluous water, and subsequently of facilitating the removal of a plant from one pot to another, without loss of roots. The surface of the reduced turf was covered with a layer of vegetable mould obtained from decayed leaves, and of sandy-loam, to prevent the growth of the grass-roots. The pots were then placed to stand upon brick-piers, near the glass; and the piers being formed of loose bricks (without mortar), were capable of being reduced as the height of the plants increased. The temperature of the house was generally raised in hot and bright days, chiefly by confined solar heat, from 95° to 105°, and sometimes to 110°, no air being ever given till the temperature of the house exceeded 95°; and the escape of heated air was then, only in a slight degree permitted. In the night, the temperature of the house generally sunk to 70°, or somewhat lower. At this period, and through the months of July and August, a sufficient quantity of pigeons’ dung was steeped in the water, which was given to the Pine plants, to raise its colour nearly to that of porter, and with this they were usually supplied twice a day in very hot weather; the mould in the pots being kept constantly very damp, or what gardeners would generally call wet. In the evenings, after very hot days, the plants were often sprinkled with clear water, of the temperature of the external air; but this was never repeated till all the remains of the last sprinkling had disappeared from the axillæ of the leaves.

“It is, I believe, almost a general custom with gardeners, to give their Pine plants larger pots in autumn, and this mode of practice is approved by Mr. Baldwin. (Cult. of Anan. 16.) I nevertheless cannot avoid thinking it wrong; for the plants, at this period, and subsequently, owing to want of light, can generate a small quantity only of new sap; and consequently, the matter which composes the new roots that the plant will be excited to emit into the fresh mould, must be drawn chiefly from the same reservoir, which is to supply the blossom and fruit: and I have found, that transplanting fruit-trees, in autumn, into larger pots, has rendered their next year’s produce of fruit smaller in size, and later in maturity. I therefore would not remove my Pine plants into larger pots, although those in which they grow are considerably too small.

“As the length of the days diminished, and the plants received less light, their ability to digest food diminished. Less food was in consequence dissolved in the water, which was also given with a more sparing hand; and as winter approached, water only was given, and in small quantities.

“During the months of November and December, the temperature of the house was generally little above 50°, and sometimes as low as 48°, and once so low as 40°. Most gardeners would, I believe, have been alarmed for the safety of their plants at this temperature; but the Pine is a much hardier plant than it is usually supposed to be; and I exposed one young plant in December to a temperature of 32°, by which it did not appear to sustain any injury. I have also been subsequently informed by one of my friends, Sir Harford Jones, who has had most ample opportunities of observing, that he has frequently seen, in the east, the Pine Apple growing in the open air, where the surface of the ground, early in the mornings, showed unequivocal marks of a slight degree of frost.

“My plants remained nearly torpid, and without growth, during the latter part of November, and in the whole of December; but they began to grow early in January, although the temperature of the house rarely reached 60°; and about the 20th of that month, the blossom, or rather the future fruit, of the earliest plant, became visible; and subsequently to that period their growth has appeared very extraordinary to gardeners who had never seen Pine plants growing, except in a bark-bed or other hot-bed. I believe this rapidity of growth, in rather low temperature, may be traced to the more exciteable state of their roots, owing to their having passed the winter in a very low temperature comparatively with that of a bark-bed. The plants are now supplied with water in moderate quantities, and holding in solution a less quantity of food than was given them in summer.

“In planting suckers, I have, in several instances, left the stems and roots of the old plant remaining attached to them; and these have made a much more rapid progress than others. One strong sucker was thus planted in a large pot upon the 20th of July, (1819;) and that is (March 1820) beginning to show fruit. Its stem is thick enough to produce a very large fruit; but its leaves are short, though broad and numerous; and the gardeners who have seen it, all appear wholly at a loss to conjecture what will be the value of its produce. In other cases, in which I retained the old stems and roots, I selected small and late suckers, and these have afforded me the most perfect plants I have ever seen; and they do not exhibit any symptoms of disposition to fruit prematurely. I am, however, still ignorant whether any advantage will be ultimately obtained by this mode of treating the Queen Pine; but I believe it will be found applicable with much advantage in the culture of those varieties of the Pine, which do not usually bear fruit till the plants are three or four years old.

“I shall now offer a few remarks upon the facility of managing Pines in the manner recommended, and upon the necessary amount of the expense. My gardener is an extremely simple labourer, he does not know a letter or a figure; and he never saw a Pine plant growing, till he saw those of which he has the care. If I were absent, he would not know at what period of maturity to cut the fruit; but in every other respect he knows how to manage the plants as well as I do; and I could teach any other moderately intelligent and attentive labourer, in one month, to manage them just as well as he can: in short, I do not think the skill necessary to raise a Pine Apple, according to the mode of culture I recommend, is as great as that requisite to raise a forced crop of potatoes. The expense of fuel for my hot-house, which is forty feet long, by twelve wide, is rather less than sevenpence a-day here, where I am twelve miles distant from coal-pits: and if I possessed the advantages of a curved iron-roof, such as those erected by Mr. Loudon, at Bayswater, which would prevent the too rapid escape of heated-air in cold weather, I entertain no doubt, that the expense of heating a house forty-five feet long, and ten wide, and capable of holding eighty fruiting Pine plants, exclusive of grapes or other fruits upon the back wall, would not exceed fourpence a day. A roof of properly curved iron bars, appears to me also to present many other advantages: it may be erected at much less cost, it is much more durable, it requires much less expense to paint it, and it admits greatly more light.” Hort. Trans. iv. 72.

Mr. Knight adds, “I have not yet been troubled with insects upon my Pine plants (having only had nine plants for about as many months), and have not, of course, tried any of the published receipts for destroying them. Mr. Baldwin recommends the steam of hot fermenting horse-dung: I conclude the destructive agent, in this case, is ammoniacal gas; which Sir Humphry Davy informed me he had found to be instantly fatal to every species of insect; and if so, this might be obtained at a small expense, by pouring a solution of crude muriate of ammonia upon quick-lime; the stable, or cow-house, would afford an equally efficient, though less delicate, fluid. The ammoniacal gas might, I conceive, be impelled, by means of a pair of bellows, amongst the leaves of the infected plants, in sufficient quantity to destroy animal, without injuring vegetable life: and it is a very interesting question to the gardener, whether his hardy enemy, the red spider, will bear it with impunity.”

In the year 1820, in June, Mr. Knight had such a house as he has hinted at, erected. Its general appearance (fig. 18.), is simple, and the roof admits as much light, as any roof that can be constructed in the present state of knowledge, in the combination of wrought iron and common glass.

The plan of this house, or pit (fig. 19.), is fifty feet in length, and ten feet wide; the furnace (a) is placed at one end; the flue proceeds from it directly to the front parapet (b), and passing along close under it to the opposite end, there terminates in a chimney (c). Instead of a pit, a curious stage is constructed, by forming cross walls (d), or rather piers, connected by arches, and finished by a gradation of flat surfaces, or steps, on which the pots are placed, so as to stand as near the glass as possible (fig. 20.)

Air is admitted by shutters, which open outwards, immediately under the stone plinth of the parapet (fig. 20. a), in which the lower ends of the iron bars are fixed; and allowed to escape by similar shutters, opening outwards, immediately under the stone coping of the back wall (b), in which the upper ends of the same bars are leaded in. The path behind is on a level with the exterior surface; the width of the cross walls the length of a brick, or nine inches, and they are finished with foot tyles; the width between them is about fifteen inches, by which means, any ordinary sized person may pass from the back path to the front flue, and water or examine the plants on each side.

This house being finished, was immediately stocked with Pines, some figs, and various other plants, all of which, Mr. Knight stated verbally, in May 1821, to various members of the Horticultural Society, succeeded admirably; but by neglect of the gardener, or rather labourer, who attended them, they were killed by an over-heat in Mr. Knight’s absence from home.[1]

The house was again stocked with plants, which Mr. Knight, in a paper read to the Horticultural Society, in November last (1821), stated to be in a most thriving condition; and a friend of ours who had made an extensive gardening tour in the North and West of England, and who saw the Pine plants at Downton Castle, also in November, declares they appeared the most magnificent he had seen on his journey; “the plants,” he says, “were stocky, and the leaves long, broad, and green; the largest were in pots fourteen inches in diameter, and their leaves reached to the glass.”

In the paper alluded to, Mr. Knight goes on to say, “I possess more than sufficient evidence to enable me to assert with confidence, that, in the culture of the Pine Apple, the bark bed, or other hot-bed, if the plants be plunged into it, is worse than useless, after the scions, or crowns, have emitted roots; and that the Pine Apple, when treated in the manner I have recommended, is a fruit of most extremely easy culture.

“It is contended, in favour of the bark-bed, that the soil in inter-tropical climates is warm, and that the bark-bed does no more than nature does in the native climate of the Pine Apple. And if the bark-bed could be made to give a steady temperature of about ten degrees below that of the day temperature of the air in the stove, I readily admit that Pine plants would thrive better in a compost of that temperature, than in a colder. But the temperature of the bark-bed is constantly subject to excess, and defect, and I contend, and can prove, that the above-mentioned temperature is very nearly given in my stove. For the temperature of the day being about 90° or 95°, and that of the night 70°, the mould in the pots will necessarily acquire nearly the intermediate temperature of 80°. It is true, that two disturbing causes are in action; the evaporation from the mould, and porous surface of the pots, and the radiant heat of the sun. But these causes operate in opposition to each other, and probably nearly negative the operation of each other, as far as respects the temperature of the mould in the pots.

“A very great number of gardeners have within the last twelve months visited my garden. Some of these were at once convinced of the advantages of the mode of culture which they saw; others have paid a second, or third visit; but every one has ultimately declared himself a zealous convert. I have never yet seen plants of the same age equally strong, nor any producing fruit better, nor indeed so well swelled; nor any equal in richness and flavour. But I have never taken off, nor shortened a root, nor taken any other measures to retard the period of fructification, with the prospect of obtaining larger fruit; and my plants have almost always showed fruit when fourteen or fifteen months old, though propagated from small and young suckers, or crowns. A great part of my Queen Pines (I have hitherto scarcely ever cultivated any other varieties) have, however, at that age, shown fruit with eight, and some with nine rows of pips; and I often see fruit of less weight growing upon plants of nearly double that age. Whether I shall be able to retard the period of fructification, or not, I have yet to learn; but I believe, I shall succeed by crowding my plants close together, so that each may receive less light.

“Pine plants will, however, grow perfectly well in composts of different kinds; but I have found that they have succeeded best when the materials have been fresh, and retaining their organic form, particularly if the pots be large, relatively to the size of the plants, which, I think, they always ought to be, for the mode of culture recommended. I have used, with advantage, the haulm of beans cut into lengths of about an inch.

“Very contrary to the conclusions which I should have been led to draw from writings upon the culture of the Pine Apple, I have constantly found that my plants succeed best in the part of my house where the flue first enters, and where the temperature is very high, varying from about 85° to 105°, and the air excessively dry. I have pointed out this circumstance to every gardener, whom I have seen in my house, and all have expressed their astonishment at the circumstance. I expected that this excess of heat would have occasioned the plants to show fruit prematurely, but this has not occurred in a single instance. What would be the quality of the fruit, if it were to be ripened in so high a temperature, I have not yet had an opportunity of knowing.

“In raising young plants, I have deviated from the ordinary mode of practice by breaking off the suckers when very young; that is, when they are not more than four or five inches long. The fruit is much benefited by their absence; and the cuttings, if placed very close together in a hot-bed, are made to emit roots with little trouble, and afford better plants than they do when they are suffered to remain long upon the parent stem. When the whole are removed at an early period, one or more very strong suckers usually spring out below the level of the soil; and from these, suffering only one to remain attached to the parent stem, and preserving the roots as entire as possible, I have propagated with much advantage, and have obtained plants which showed fruit strongly at seven months, dating from the period at which the sucker appeared, like a strong head of asparagus, at the surface of the soil.

“The success of my experiments, in the first house which I erected, (and to which the foregoing account exclusively refers,) led me to erect another house (figs. 18. 19. and 20.) in the summer of 1829. In this I attempted to obtain the greatest possible influence of light, and command of solar heat; inferring, from having observed Pine Apples to ripen tolerably well with very little light, that I should be able to ripen them in perfection late in the autumn, and early in the spring, particularly at the latter period, in which, alone, I set a very high value upon the species of fruit. The height of the back wall (fig. 20.) of this house is eight feet six inches, and that of the front wall is one foot six inches, and its breadth ten feet, inside measure, with an iron curvilinear roof, (fig. 18.) of the kind of bar invented by Mr. Loudon, of Bayswater. This house is fifty feet long, (fig. 19.) and capable of containing two hundred fruiting Pine plants. The curvature of the roof rises just one foot in twelve. The glass is laid in a composition of two parts white lead, with oil, and three of flint sand, and the overlaps of the glass are closely filled with the same material. It is, consequently, very nearly air-tight; and no means are given for the air to enter, or escape, except by apertures immediately under the copings of the front and back wall, (a and b, fig. 20.) which can be efficiently closed at any time. It is, consequently, an instrument of very great power, and requiring, of course, much attention to ventilation: of which I had rather a lamentable proof in the last spring, when my plants were all burned, and spoiled in a few hours; the person who had the care of them having left them in a bright day closely shut up. The fault was not, however, in any degree in the house, for the plants were, previously, much the strongest, and the best I ever saw; and I believe, they would have afforded most beautiful fruit. I furnished the house again with plants as expeditiously as I could, chiefly in July; and I have since kept the temperature of it nearly between 70° and 95°, with a wish to make the plants show fruit and blossom in the present month (October.) In this, I have in part succeeded, though many of my plants have flowered a fortnight or three weeks sooner than I wished. The fruit is swelling well, and, I believe, will receive sufficient light through the winter to enable it to ripen in much perfection. The excellence of a few Pine Apples, which ripened in this house in the last winter, leads me almost to doubt, whether the fruit in it will not ripen better, early in the spring, than in the middle of the summer, for I have observed that this species of plant, though extremely patient of high temperature, is not, by any means, so patient of the action of very continued bright light, as many other plants: and much less so than the Fig and Orange tree: possibly, having been formed by nature for inter-tropical climates, its powers of life may become fatigued, and exhausted by the length of a bright English summer’s day in high temperature. Being a plant of low stature, nature has also probably given it the power to ripen its fruit and seed, in the shade of other plants, in its native climate; and I discovered in the last summer, that it possesses the power to ripen its fruit perfectly in a lower temperature than I previously thought it capable of growing in.

“In the month of June, I gave a couple of Pine plants, which had shown fruit at six months old, and were of small size, and no value, to a child of one of my friends, to be placed in a conservatory, in which no fires were kept during the summer. In July, a storm of hail destroyed nearly, or fully, half the glass of the conservatory; and its temperature, through the summer and autumn, had been so low, that the Chasselas grapes in it were not ripe in the second week in September. In the second week of the present month (October) one of the Pine Apples became ripe, having previously swollen to a most extraordinary size, comparatively with the size of the plant; and upon measuring accurately the comparative width of the fruit, and of the stem, I found the width of the fruit to exceed that of the stem in the proportion of seven and three-quarters to one. The fruit had, of course, been propped during all the latter part of the summer, the stem being wholly incapable of supporting it. The taste and flavour of this fruit were excellent, and the appearance of the other, which is not yet ripe, and is of a larger size, is still more promising. I purpose to profit by this result in the next summer; and I hope to be able to communicate some further information to the Society in the autumn. I feel perfectly confident, that if the roots of these plants had grown in a hot-bed of any kind, their sap would have been impelled into other channels; and that their fruit would not have attained, in any degree, the state of perfection which I have described.”

This is the latest printed account of Mr. Knight’s experiments on the Pine Apple. It would be premature to draw any general conclusions in so early a stage of their progress, and might excite prejudice to anticipate the final result. That the Pine plant will grow and thrive without what is technically called bottom heat, is an obvious truth, since no plant in a state of nature is found growing in soil warmer than that of the superincumbent atmosphere. But to imitate nature, is not always the best mode of culture; for the more correct the imitation, the less valuable would be the greater part of her products, at least as far as horticulture is concerned. What would our celery, cabbage, and apples be, if their culture were copied from nature? Though the Pine Apple will grow well without bottom heat, it may grow with bottom heat still better; and though the heat of the earth, in its native country, may never exceed that of the surrounding atmosphere, it does not follow that earth heated to a greater degree may not be of service to it, in a state of artificial culture. But admitting, for the sake of argument, that the Pine plant could be grown equally well with, as without bottom heat; still it appears to us that the mass of material which furnishes this heat, will always be a most desirable thing to have in a Pine stove, as being a perpetual fund of heat for supplying the atmosphere of the house, in case of accident to the flues or steam apparatus. Besides it appears from nature, as well as from observing what takes place in culture, that the want of a steady temperature and degree of moisture at the roots of plants is more immediately and powerfully injurious to them than atmospheric changes. Earth, especially if rendered porous and spungelike by culture, receives and gives out air and heat slowly; and while the temperature of the air of a country, or a hot-house, may vary twenty or thirty degrees in the course of twenty-four hours, the soil at the depth of two inches would hardly be found to have varied one degree. With respect to moisture, every cultivator knows, that in a properly constituted and regularly pulverized soil, whatever quantity of rain may fall on the surface, the soil is never saturated with water, nor, in times of great drought, burnt up with heat. The porous texture of the soil and sub-soil being at once favourable for the escape of superfluous water, and adverse to its evaporation, by never becoming so much heated on the surface, or conducting the heat so far downwards as a close compact soil.

These properties of the soil relatively to plants can never be completely attained by growing plants in pots, and least of all by growing them in pots surrounded by air. In this state, whatever may be the care of the gardener, a continual succession of changes of temperature will take place in the outside of the pot, and the compact material of which it is composed being a much more rapid conductor of heat than porous earth, it will soon be communicated to the web of roots within.

With respect to water, a plant in a pot surrounded by air is equally liable to injury. If the soil be properly constituted, and the pot properly drained, the water passes through the mass as soon as poured on it, and the soil at that moment may be said to be left in a state favourable for vegetation. But as the evaporation from the surface and sides of the pot, and the transpiration of the plant goes on, it becomes gradually less and less so, and if not soon re-supplied, would become dry and shrivelled, and either die from that cause, or be materially injured by the sudden and copious application of water.

Thus, the roots of a plant in a pot surrounded by air, are liable to be alternately chilled and scorched by cold or heat, and deluged or dried up by superabundance or deficiency of water, and nothing but the perpetual care and attention of the gardener to lessen the tendencies to these extremes could at all preserve the plant from destruction.

To lessen the attention of the gardener, therefore, to render the plant less dependent on his services, and, above all, to put a plant in a pot as far as possible on a footing with a plant in the unconfined soil, plunging the pot in a mass of earth, sand, dung, tan, or any such material, appears to us a most judicious part of culture, and one that never can be relinquished in fruit-bearing plants with impunity. Even if no heat were to be afforded by the mass in which the pots were plunged, still the preservation of a steady temperature which would always equal the average temperature of the air of the house, and the retention, by the same means, of a steady degree of moisture, would, in our opinion, be a sufficient argument for plunging pots of vigorous growing, many-leaved, or fruit-bearing plants.

Such are the observations that we think may be made relatively to Mr. Knight’s plan, without prejudice to whatever new lights he may throw out on the subject. Had it been brought forward by a less eminent horticulturist, it would not have claimed so much attention, as the plan of growing Pines without bottom-heat is generally considered to have been tried first by M. Le Cour, and subsequently by various others, and abandoned. In Mr. Knight’s hands, however, whether it fail or succeed, it is certain of doing good, by the observations it will elicit from the fertile and ingenious mind of so candid and philosophical a horticulturist.

Sir William Edward Rous Boughton has erected a house or pit at Downton Hall, similar to that of Mr. Knight, but rather wider.[2] Pines are grown in it on Mr. Knight’s plan, but the plants were not in a thriving state in November last. Charles Holford, Esq. of Hampstead, is also a disciple of Mr. Knight as to the culture of this fruit, but he has not yet been very successful.

Sect. II.
Of other Improvements in the Culture of the Pine Apple, by different persons.

We shall first notice the improvements which respect bottom-heat, and begin with noticing an attempt made by Mr. Thomas Jenkins, of the Portman Nursery, London, to warm both the pots in which the plants are grown, and the air of the house, by the heat generated by fermenting stable-dung placed in a vault beneath.

It is only within the last three years that Mr. Jenkins has begun to grow the Pine Apple to any extent; he brings forward the plants in hot-beds and deep frames, inclosing beds of tan, and heated by linings of dung. As an economical part of the construction, we may mention that he substitutes wattled hurdles for the lower part of the frame, in contact with the tan, by which means a saving in the first cost is effected, and the heat of the dung penetrates much more readily to the tan.

Most of the plants are fruited in these pits, but some are fruited in a house, (fig. 21.) which “though furnished with flues, yet these have been very little used. The heat imparted to the plants is produced by the fermentation of stable-dung in a pit below the plants, the top of which is covered by tiles supported by iron rafters, with the joints closely cemented, to prevent the passage of steam into the house. The pots are neither bedded in tan, nor in mould, but stand on the tiles, and the interstices between them warm the air of the house.”

The dung is managed as in West’s pit (fig. 22.), but with the addition of being watered after it is thrown in, which is found to promote fermentation, and the intensity of the heat.

One of the earliest instances of steam being used as a bottom-heat with which we are acquainted, was that by Mr. Butler, gardener to the Earl of Derby, at Knowlesly, near Liverpool, in or about 1792. It had been used twenty years before, but chiefly for other purposes. Speechly, in 1796, knew only two instances in which steam was applied as bottom-heat; and, with M’Phail, does not think it will finally answer as a substitute for tan. Instances in which it is adopted, are now much more numerous; but time sufficient has not elapsed, and the opinions of gardeners are yet too unsettled on its merits to enable us to recommend it for adoption in general practice. For heating the atmosphere of hot-houses, there seems little (or at least much less) doubt of its being preferable to fire-heat.

Count Zubow, at St. Petersburg, employed steam to heat a pit or cistern of water, over which, at about three inches distance, a frame, covered with faggots, was placed, and on this was laid the earth, in which his Pines and other exotics were planted without being in pots. The plan is said to have succeeded, and a wholesome temperature to have been obtained and communicated to the mould above the faggots.

Mr. Gunter, as before observed, (Chap. IV. sect. 13.) had already tried the use of steam as a bottom heat without success.

Mr. John Hay, horticultural architect, tried the use of steam so early as 1794, when gardener at Preston Hall, near Edinburgh, and he gives the following account of his apparatus and success in the Memoirs of the Caledonian Horticultural Society. “The application of steam to forcing-houses early caught my attention. The first that I designed and executed in Scotland on this plan, were at Preston Hall in Mid-Lothian, in the year 1794. The fruiting Pine-stove, which is in the general suite of houses, with two peach-houses on the west, were originally adapted to steam. I entertained the hope, that steam thrown into a chamber, in the bottom of the plant pit, would act as a proper substitute for bottom heat in place of tan, as none of that substance was to be found nearer than four miles distant, and when wanted was often difficult to be procured. Other more general considerations also made me desirous of procuring some substitute, particularly the necessity of repeatedly shifting the plants to renew the heat, when the bark in the plant-pit gets cold: these shiftings, besides the trouble, often retard the growth of the plants. Again, if the heat of the fermentation of the tan rise much above ninety-six degrees, (which it often does), and if the pots be fully plunged in the tan at such a time, many instances have been known of the roots of the plants being burned, and some of them being destroyed altogether. This, indeed, may be considered as one of the principal reasons why so many are unsuccessful in the culture of this fine fruit. With the view of obviating the above difficulties, the bottom of the fruiting Pine-pit was constructed with a chamber below, into which steam was introduced by means of copper and lead pipes from a boiler placed in the shades behind: the top of the chamber was constructed of rafters, on which were placed broad grey slates, laid on loose, without filling up the vacancies between them. The not making them close, I afterwards found to be an error; for the moisture, from the condensation of the steam, penetrating through the openings at the joining of the slates, communicated too much wetness to the bottom of the pots; but I found, that there was a sufficient quantity of heat to be obtained from the steam for heating the plant-pit, provided the bottom were close. I therefore discontinued this plan; and I had not an opportunity of making any farther experiment on the subject in this place. From the same boiler, I conducted into the two peach-houses adjoining, a range of pipes furnished with steam-cocks. They passed the whole length of the houses, (101 f. 6 in.). By means of these, the peach-houses were regularly steamed near one hour a-day in the evening, in the time of flowering and of fruit-setting. Steaming, it may be remarked, is very important at these times. In after periods, when I had not an apparatus for the purpose, I always steamed the peach-house with a large piece of cast-iron, made red hot in one of the furnaces, and put into a white-iron pail nearly full of water; the whole water thus evaporating into steam. I was always successful, while in practice as a gardener, in raising a full crop of peaches; and think that much was owing to attention to steaming.

“I afterwards erected Pine-stoves for John Hervey, Esq. of Castlesemple, to be heated by steam; and one of the plant-pits had a chamber below, with a close bottom, into which chamber, steam was thrown by means of cast-iron pipes. About the same time, I was applied to by Sir Hew Hamilton Dalrymple, Bart. (through Mr. James Dodds, his gardener), to examine his Pine-stoves at Bargany, and to report whether I thought they could be improved, as he hitherto had not been so successful in Pine-Apples as he expected. One principal cause was, the difficulty of obtaining tan. Upon my report, it was to be determined, whether to give up the Pine-Apple culture altogether, or endeavour to improve the stoves.

“Upon examining, I advised the heating of the atmosphere of the houses with steam; and in place of using tan, the heating of the bottom of the plant-pit with steam also.” This advice was adopted, and eighteen months after the plan was executed, the gardener, Mr. James Dodds, gives the follow-account of his success.

“It is now eighteen months since I first began to heat the Pine-stoves here with steam. I have thus been enabled to give it a fair trial, and I am fully satisfied that it is superior to the old method of heating by fire-flues. I have found the plants to grow more luxuriantly, and perfectly clean of any kind of insects. The moist heat arising from steam is well known to be hostile to all kinds of vermin. It is, besides, more economical: our Pine-stoves here are seventy feet long, it formerly took two fires to keep up the heat of the atmospheric air of the house, whereas in the new method of heating by steam, one fire to heat the boiler is sufficient, except in very cold nights, when I have found it necessary to light a very small fire to the flue, to meet the decline of the steam in the morning, and this only to the fruiting-house in the spring months, when the Pines begin to show their fruit. In short, I have found no difficulty in keeping up the heat of the house to sixty degrees, by making up the fire to the boiler at ten o’clock at night, and at six o’clock in the morning.

“With regard to the bottom heat for the Pine-plants, by steam from the same boiler, I find, by allowing the steam to remain in the chamber below the plants about two hours a day, the pit is kept constantly at the temperature of from ninety to ninety-five degrees, which I have found to be as high as the roots of the plants are able to bear. I would, therefore, say ninety degrees to be the standard height, which I have myself adopted, allowing it to fluctuate down. If our succession Pine-pit had been altered to have been heated by steam, as the fruiting one is, which the boiler is perfectly able to do, the saving in tan alone would more than pay the interest of all the money laid out on erecting the whole steam apparatus.

“The above is my candid opinion on the subject, as far as my practice has enabled me to speak. I am, &c.

“James Dodds.”

The best stoves for combining the culture of the Pine and Vine in Scotland, have been constructed by Mr. Hay, of which fine examples occur at Lord Duncan’s, Lundie-house, near Dundee, and the Earl of Roseberry’s, at Dulmeny-park (fig. 23.), near Edinburgh.