APPENDIX.

On Heating, Ventilating or Aerating, and Covering.

Since the publication of the first edition of this work in 1844, the views expressed in the second chapter, with reference to structures best adapted for Cucumber culture in the winter season, have met with much corroborative support. Respecting the questions of heating, ventilation, and covering, a few more words may be added.

I have before recommended hot water tanks for supplying bottom heat, with attached pipes for the circulation of hot water to warm the atmosphere. I can see no reason for recommending any other arrangement now; for the experience of successive years goes to show that hot water, applied on sound principles, is, above all other means of heating, effective in its operation; and as to the question of expense, raised as an objection to it by some, it is sufficient to say, that, although one hot water apparatus may be fitted up in an expensive manner, another may be rendered perfectly successful in its operation, at the same time that it is extremely simple in its arrangements, and correspondingly inexpensive in its cost.

A seeming error in the engraving, at p. [18], has been pointed out to me. In the description of the sketch it is stated that, “a series of pipes attached to the same boiler [which heats the tank] would supply the requisite heat to the atmosphere.” The sketch itself shows these pipes to be considerably above the level of the water in the tank, and where they could not, consistently with the other arrangements, be thus employed. This may be explained thus:—the sketch was introduced rather for the purpose of illustrating certain proposed arrangements, as regards bottom heat and ventilation, than as furnishing an exact and detailed design for a model structure; and thus it happened that the pipes were merely shown to be placed at the front part of the house, to indicate that this was their proper relative position. There would be no practical difficulty in placing the pipes lower down, and nearly close to the front wall, so as to admit of the proposed connection; all that would be required to effect this, being to fix the slab, on which they rest—and which prevents the air from rushing upwards into the atmosphere of the house at this point—in a sloping position, instead of a horizontal one.

The principle involved in the plan proposed for aëration or ventilation, is no doubt a sound one; and though the plan which is more particularly described may be modified and varied, yet it is believed to be efficient for its intended purpose.

There can be no doubt that the admission of cold air to a structure in which tender plants are being forced, either during winter or early spring, is materially hurtful to the plants, in proportion to the tenderness of their constitution; and the Cucumber being, under those circumstances, a plant of a very tender and delicate nature, is especially susceptible of harm from this source. As a consequence resulting from this fact, there can be little hesitation in affirming that whatever fresh or external air it may be necessary to admit, during the period referred to, should be warmed before it reaches the plants, and in being warmed not burned, but supplied with the additional moisture its increased heat capacitates it to take up, and which, to be congenial to vegetation, it requires. This is provided for by the plan already recommended, where the cold air is made to pass through the tank containing the heated water which warms the soil. By a perfectly practicable modification of this arrangement, not only may this result be secured, but also the continual circulation of the internal atmosphere may at pleasure be assisted and accelerated, during the time when it might not be necessary to admit fresh air. This would be an additional advantage. The arrangement proposed to effect this, is to conduct the cold external air through a heated chamber containing the tanks—these latter being covered, but also admitting of being opened to any extent to supply moisture or steam in the proportion required. The cold air, after passing upwards through the chamber, escapes at the front of the house, and ascends to the upper part of the house, from whence it finds its way downwards near the back wall, and there again enters the chamber, through openings provided for the purpose. The circulation of the internal atmosphere would be thus facilitated and accelerated, even without the admission of any current of external air, for, of course, there is more or less of this kind of movement going on in the atmosphere, wherever and in whatever form a source of artificial heat is present. Another mode of combining internal atmospheric motion, with ventilation, and by which the cold air is warmed before it reaches the plants, has been practised with very marked success, in a vinery at Park-hill, Streatham, Surrey; and I have described it in the Journal of the Horticultural Society[1] as follows:—“This plan consists in passing a zinc pipe, thickly perforated with small holes, from end to end of the vinery, and exactly beneath the range of hot water pipes, which heat the structure. In the outer [end] wall, communicating with this perforated pipe by means of a kind of broad funnel, a register valve is fixed, by which the admission of air can be regulated with the utmost nicety, or the supply be shut off altogether: this valve is fixed a little below the level of the perforated pipe. The action of this contrivance was evident enough from the motion communicated to the foliage of the vines; and its effects were apparent in the unusually healthy and vigorous appearance they bore, until their period of ripening. In this case, sufficient moisture was kept up by syringing the walls and pipes, wetting the pathway, and by the use of evaporating troughs, placed on the metal pipes, and kept constantly filled with water.”

In another communication published in the work already quoted,[2] after alluding to the now well-known garden truism, that a comparatively low night temperature is indispensable to the maintenance of vigorous growth in plants of all kinds, I have advocated a more extended adoption of the practice of night covering hot houses, as a means of permitting the low night temperature required, and at the same time securing the plants against the extreme cold to which they would thus be sometimes liable. From the changeable nature of our climate, there is some difficulty in apportioning the degree of applied heat, so as to suit exactly the requirements of the plants in these respects; and it is especially difficult to maintain with certainty the low degree of night temperature which would be desirable, and at the same time avoid risking the safety of the plants, through a sudden declension of the temperature of the exterior air. At present this difficulty has to be met by extraordinary care on the part of the gardener, and often by serious encroachments on his proper time for study and for rest: even then sometimes without success. This end would be much more effectually and certainly secured by a complete system of covering hot-houses and forcing-houses; and this plan would secure the further advantage of avoiding the undue stimulation of the plants by a then unnecessary amount of heat, applied solely to prevent the very evil which covering also prevents, namely, the risk of excessive cold during the night.

The principle upon which a covering acts most efficiently, is that of enclosing a complete body or stratum of air exterior to the glass, this body of air being entirely shut away from the surrounding outer atmosphere. Air being a bad conductor of heat, the warmth of the interior is by this means prevented from passing to the exterior atmosphere; or, in other words, the exterior atmosphere, being prevented from coming in contact with the glass, cannot absorb from the interior any material proportion of its heat. To secure this advantage, however, the coverings must be kept from contact with the glass, and they should extend on every side where the structure is formed of materials which readily conduct heat—such as glass or iron. The coverings should in fact form neither more nor less than a close outer case.

One point connected with the application of these coverings, which I consider would constitute an improvement, and which, as far as I am aware, has never been acted on, is that of having them to fit so accurately as to exclude the external air (a matter of no difficulty in the degree required), and then to have a series of ventilators provided, to stand open during the night, whereby an interchange of the atmospheric volume would take place throughout the night, without exposing the plants to contact with cold air. The stagnation of the internal atmosphere would thus be prevented, in consequence of the interior air and the air between the glass and the covering being of different degrees of density, owing to their being differently charged with heat. By this plan, therefore, I conceive that direct benefit would accrue to the plants; and it would also materially assist in preserving that cooler—but not cold—night temperature, which the fear of injury from frost prevents from being more fully realised in ordinary cases.

The annexed diagram represents one of the many ways in which this idea might be carried into practice. It will be understood that, as here shown, the side shutters and end shutters (the latter not indicated), fit into grooves, the upper groove being attached to iron pins, and thus fixed at a proper distance from the building, without obstructing the passage of air along the enclosed space; and that on the lower side being so fixed as to exclude the external air in that direction. The top or roof shutters also run into a groove along the ridge of the roof, and at the lower end fix close down to the top of the side shutters, fastening with a button. Each of the shutters should have a projecting fillet fixed on one side, so as to shut close over the adjoining one. The shutters themselves should of course be made of light frame-work, strengthened where necessary, with small iron rods. The material used for covering them may be the asphalte felt, now manufactured extensively for roofing purposes, or strong brown paper, coated with tar; the latter is used extensively in Germany for this purpose, and is found to be very durable and cheap; it is there even preferred to every other material.

Though the covering of hot-houses has been already practised in some cases, I am not aware of any one having adopted a close covering with the view to facilitate ventilation or aëration during the night. It appears to me that the circulation of air, secured by the means here proposed, would have much influence in excluding cold, whilst at the same time it would prevent the interior from becoming too warm and close.

On Transplanting and the use of Turf Pots.

I have, at p. [26], given what appear to me to be some of the principal reasons against the practice of transplanting, or planting out, Cucumber and other plants. When this is done after any quantity of roots are produced, some injury or check must be sustained during the process; and checks of this kind are opposed to the realisation of the greatest results within the shortest period, which of course is the great object in view. Where it is inconvenient to plant the seeds in the places the plants are intended to occupy, or to put out the young plants during the earliest period of their development, or where propagation by cuttings or layers, is adopted, and the plants of course have to be potted separately, so as to be in a removable state, the following simple plan may be adopted, and will be found to combine all the advantages and conveniences attending the use of pots, with the avoidance of the evils of transplantation, &c. The plan referred to, consists in the employment of turf or peat, so contrived as to supply the place of pots, and which of course at the time of planting is simply placed, along with the plant it contains, at once into the soil, without in the least disturbing the roots, which, growing through the substance of the turf, extend beyond it in all directions into the free soil provided for them. These turf pots are made of spongy, fibrous turf—whether loamy or peaty is not material, provided it is full of fibre, so as to admit of being readily traversed by the roots. The grassy surface is evenly removed, and the under-turves are cut three or four inches in thickness, and are then divided into squares of about three inches across. The centre of each of these little squares is taken out by means of an iron scoop, such as that represented in the annexed sketch; and this is then filled up with soil, and the plant, or seed, or cutting, or layer, inserted as if it were into an ordinary flower pot. It will be obvious that by this plan, every plant is independent and perfectly removable—thus securing the convenience of sowing or planting and rearing the plants in pots during their earliest stages: on the other hand, at the time of planting out permanently, the plant, turf, and all being set carefully into the soil, no check is sustained, because the roots remain undisturbed, and may, as they advance, penetrate through the turf into the prepared soil which surrounds them; in this way the advantages of sowing or planting at the very first in the position the plants are intended to occupy permanently, are secured.

This plan of sowing seeds, or of planting young plants intended for transplantation, into pots made of turf, is not only applicable to cucumbers, but might be very extensively adopted in the case of annuals and half hardy plants raised in frames, during the spring, in large quantities for the flower garden. In these cases, however, as the quantity that could be reared within a given space would be an object, the turves should be as small as possible in their lateral dimensions—a bore of two inches and a half, with half an inch on each side, thus making the diameter three inches and a half, would be found convenient in this respect. For cucumbers, however, or when the plan was applied to any special object, a larger size might be employed, which would allow of the plants attaining a larger size before it would be necessary to place them in their permanent positions.

On Watering the Soil.

In the diagram at p. [18], and the description of it at p. [20], I have indicated and recommended a plan of moistening the soil by pouring water down beneath the soil: this was to be done by the help of tubes provided for the purpose. The soil was supposed to rest on the top of the hot water-tank, which was to supply bottom heat; and immediately beneath the soil, a layer of open rubble was proposed to be placed, among which the water applied might find its way, and gradually moisten the superincumbent soil. Mr. Hunter, gardener at Mawley Hall, in detailing[3] his sixteen years’ experience in tank-heating, has in great measure corroborated these views; and as his corroboration of the plan I have recommended, embodies some useful hints, I will quote the substance of his remarks:—“I had a pit erected, thirty-eight feet long, seven and a half wide, divided into four compartments, for growing melons and cucumbers, with a tank extending the whole length of the pit, six feet wide and six inches deep. Across this I put larch spars, and upon them turves, with the grassy side downwards, and on them the soil for the melons and cucumbers. The plants grew and did well for a time, but they were of short duration in comparison with the dung-bed. Instead of the moisture ascending through the soil as I expected, I found that the heat from the tank dried the turves and soil next to them as dry as dust, and that there was no such thing as obtaining a moist heat from hot water without the soil was in contact with it. Next year I put broken stones upon the spars, and turves upon them, and made my arrangements so that I could occasionally run water in the tank to wet the turves and the soil next them. This was an improvement; and I went on prosperously for some years, till the spars began to decay. I then had iron bars put across, and two of the compartments covered with squares, a foot in diameter, and one inch thick; the other two with slates; both slates and squares jointed with Roman cement, to prevent the soil from getting into the tank, as I had found the inconvenience of it when using the spars. I put some broken stones upon the covers, and turves upon them, and then the soil. Here my original difficulty occurred; the soil next the covers got too dry, and to moisten it from above was impracticable, without making the soil a complete puddle, which would have stopped the healthy growth of the plants. To remedy this, I put six small earthen pipes into each division, the one end resting upon the tank covers, the other standing up above the soil. When I found by the watch sticks that the soil was getting dry, I poured water down the pipes through a tin funnel which I had made on purpose; this spread itself over the surface of the tank covers, and diffused a gentle moisture to the soil, so congenial to the growth of plants. This was a move in the right direction. I then thought that it would be better to pour the manure water down upon the tank covers, which I have done since. I found the broken stones over the tank covers troublesome; they were also a harbour for wood-lice. I now use only a layer of leaves next the covers, and they are cleared out with the soil.”

On Atmospheric Humidity.

Cucumbers cannot at any time be successfully grown in an arid atmosphere, although, during the winter season, they require a much less proportion of atmospheric humidity, than under the influence of longer days and brighter light; and conversely, the degree which would be necessary to secure their welfare in summer, would be fatal to them in winter. An experienced gardener would tell almost instinctively, at either season, whether a sufficient supply was present or not; but less experienced cultivators would need some index, or register, to guide them. Such an index is afforded by the hygrometer; but most of the kinds of hygrometers are delicate instruments, and hardly suited for garden use. What is needed in this case is, not an instrument which requires minute observations and calculations, but something that will at once indicate the atmospheric humidity as plainly as the thermometer does the temperature, and which may be as easily read off and understood. Simmons’ hygrometer, recently introduced to the notice of horticulturists, professes to supply this desideratum; and though, perhaps, not a sufficiently accurate instrument for purely scientific purposes, yet, as simply and clearly indicating what is at least an approximation to the existing degree of atmospheric humidity, it is to be regarded as a useful garden hygrometer. By it, the degree of dryness or humidity is indicated on a dial-plate, by means of a moveable arm resembling the hand of a clock. The dial-plate is marked off into degrees, expressing the amount of moisture in the air, between what is observed when the instrument is plunged in water on the one hand, and exposed to excessive dryness on the other. As my own experience of this instrument, though favourable to its use, is still but limited, I cannot do better than introduce here the following remarks of Mr. Beck, of Isleworth, a very successful cultivator of plants, and one who has had considerable experience in the use of these instruments. It will be observed that Mr. Beck’s standard for the orchid-house will be about suitable for cucumbers.[4] Mr. Beck observes,—“The skilful gardener, observing the pointer to advance with dryness and return with moisture, will soon form a standard for himself, by which to regulate his stove, greenhouse, &c.; still some general scale is desirable. Two conditions must be carefully observed:—1. The instrument must neither be hung in the sun, nor where it will be liable to get wetted or saturated. 2. It must not be subjected to greater heat than is suited to vegetable life. For the six months commencing with August and ending with January, 40 deg. in, the morning, increasing to 60 deg. about noon, and declining again to 40 deg. at night, is about the right scale for the orchid-house; whilst a range from 50 deg. to 80 deg. would be suitable for both the stove and greenhouse in those months. In the other half year, February and July inclusive, 30 deg. to 40 deg., morning and evening, running up to 80 deg. in the middle of the day for the orchid-house; 40 deg. and 50 deg., and up to 70 deg. for the stove; and 50 deg. to 80 deg. for the greenhouse, will prove very suitable. The above scale is desirable, but I do not say it is always attainable. Ours is an uncertain climate; sometimes a dry east wind will almost parch us up; at other times a southerly one, with wet, will cause a superabundance, which will have to be corrected, possibly by a gentle fire, and a free admission of air. The alteration hereby effected in the atmosphere of the houses will soon be evidenced by the hygrometer, and mildew and fogging off be kept at a distance. Opposed to an excess of moisture in the dull months of the year, is the dryness consequent on the summer and autumnal sunshine. Then, during the heat of the days, the instrument will seem to have run wild. Throwing water on the floors of the houses, and every means of increasing the amount of moisture, seems but of little or temporary avail; Simmons will go up, spite of all, to 90 deg. or 100 deg., and none the worse either, for it is still a faithful indicator, and as sure as the day declines, and the heat of the sun is withdrawn, so will it come back to a suitable point, when the plants are watered and the floors are wetted for the night. Remembering then, the variableness of our climate, I candidly admit that I consider any precise directions of very little value. None can be given that shall be implicitly followed, or on which success shall certainly attend. Horticultural practice should be made dependant upon ever-varying circumstances.”

Mr. Belville, of the Royal Observatory, has constructed the following Table, from a series of observations made with Simmons’ hygrometer in connexion with the dew point, as obtained by a Mason’s hygrometer, or a dry and wet thermometer.

Range
of Simmons’
Hygrometer.		Mean
Humidity
of the Air.
20°to30°1·00 Extreme saturation; air precipitates moisture at a fall of temperature.
30..400·96
50..600·89
60..700·77}
70..800·72Ordinary fine dry weather.
80..900·67
90..1000·59
100..1200·50 Air contains one half of the moisture it is capable of holding in solution; in England very dry weather.

Example:—Suppose hygrometer read 45°, the mean humidity corresponding is 93. Again, if hygrometer read 90°, the mean humidity corresponding is 59°.

Mushrooms. (See p. [22].)

Convenience for growing mushrooms may always be planned in a cucumber house; and as these excellent fungi are universally approved, it may be useful to append an epitome of the mode in which they should be cultivated.

The best, or, at least, most convenient situation for the bed, would be beneath that provided for the cucumber plants (see p. [18]). The front may be formed of two course of brick-on-edge, and if divisions are required, they should be formed in the same way. The bottom should be made even, and rendered dry. The material for forming the bed itself consists of short stable litter, with horse-droppings, but chiefly the latter, brought to a certain state of fermentation. The droppings and litter should be obtained daily from the stable, until enough for a bed is collected; it should, from day to day, be thrown up into a flattish heap, in a dry place, where it will ferment very slightly. As soon as enough is got together to begin to ferment, the heap must be turned over; and in these turnings, the outer and inner parts of the heap, as well as the fresh and the fermenting, must be well mixed up together; the heaps should be turned every second day, and should never be made large, or else the dung would become both too hot and too dry, either of which would spoil it. To avoid this, the heaps should be flat and shallow, with as much outside as possible; in this way the air, acting on a considerable portion of it, renders it rather dry, and checks too rapid fermentation. This preparation must be continued until the whole mass is brought to an uniform mild, dryish state of fermentation. Then the bed may be made in the following manner:—About three inches of the prepared dung is laid evenly over the bottom, and is beaten down firmly with a flat heavy wooden mallet. Another layer is then put on in the same way, and this is repeated until the bed is formed to a thickness of about six inches. The next two inches of the dung should have about a sixth part of light turfy loam reduced to mould, and sifted, mixed with it to give it body. The bed is now prepared, and is to be spawned as soon as it is seen that it does not heat violently. The heat ought not to exceed 90 degrees: if it reaches higher than this, holes must be made, a few inches apart, to let the heat pass off, and in a day or two these may be filled up again. The spawn is to be put in when the heat ranges about 75 degrees; lumps of spawn about as large as a small egg may be used; a hole should be made with the fingers about two inches deep, the spawn inserted, and the material of the bed closed about it. Probably by this time there will be no danger of overheating, and if so, the soil may be put on; if, however, there is any inclination to overheat, wait till it has passed off before putting on the soil. The soil used should be decomposed turfy loam, moderately dry, so as to bear compression without running together like paste, but damp enough to become firm, close, and even, when beaten closely. About two inches in thickness should be put on, and this is to be beaten down quite firm and close. The beds are then finished. It is as well to cover the surface with a thin layer of short hay, to prevent it becoming quite dry. Mushroom beds seldom require water; after they have been some time in bearing, the beds sometimes get dry, and in such cases, if they have a moderate soaking of tepid water, and the surface is covered as before, a new crop will spring up. The covering is best removed when the beds are in bearing. It is seldom advisable to apply water when the beds are coming into bearing. Water should never be used in any other than a tepid state.

Mushrooms are most prized in the summer, though the atmosphere of a cucumber-house would not then be suitable for them, unless the space about them could be closed in, so as to retain a close, somewhat humid atmosphere. They would succeed very well without being enclosed, during the season for forcing cucumbers.

Under the treatment which has been detailed, the beds would usually come into bearing in about six weeks from the time of spawning; and, under favourable circumstances, would continue in bearing for two or three months.

Footnotes:

[1] The Journal of the Horticultural Society of London, vol. I. p. 114.

[2] Ib. vol. II. p. 29.

[3] Gardener’s Journal, 1847, p. 339.

[4] Gardener’s Chronicle 1847.

Transcriber’s Notes:

Other than the corrections noted by hover information, printer’s inconsistencies in spelling and hyphenation have been retained.

Punctuation has been corrected without note.