The Amateur’s Greenhouse and Conservatory

Introduction

THE AMATEUR’S GREENHOUSE AND CONSERVATORY.

INTRODUCTION.

“Who loves a garden loves a greenhouse too. Unconscious of a less propitious clime, There blooms exotic beauty, warm and snug, While the winds whistle and the snows descend.

All plants, of every leaf, that can endure The winter’s frown, if screened from his shrewd bite, Live there, and prosper.”

Cowper.

The briefness of the British summer and the frequent interruptions to out-door enjoyment, occasioned by adverse weather, render the well-kept plant house a place of most agreeable resort at every season of the year. The capabilities of our climate are truly wonderful, for we may, with a considerable degree of safety, enrich our gardens with plants that are natives of subtropical and arctic climes; and yet we find our varying selection of subjects seriously restricted unless we are aided by plant houses of some kind or other, to ensure for our favourites better conditions than the unprotected soil and free atmosphere would afford them. Hence, for pleasure and utility alike, the various structures that have been adopted as aids in plant-culture are of the utmost importance to the horticultural amateur, for they bring within the range of his observation and practice the vegetable products of climes that differ greatly in conditions from our own, and they may be so managed as to provide the best possible imitation of a perpetual spring, or of “summer all the year round.”

The object of this little work is to afford some useful information, systematically arranged, on those departments of plant-house construction and plant cultivation which may be properly considered under the general heads of the “greenhouse” and “conservatory,” in which a temperate climate is maintained, as distinguished from the “stove,” the “orchid-house,” and other structures in which a tropical climate is required for the advantage of tropical plants. Considering the treacherous nature of our climate and the length of the winter season, it cannot be said we have as yet attained to a full knowledge of the value of glass in horticulture. Nevertheless immense progress has been made since glass and bricks and timber were rendered free of duty, and the vast number of patented plant houses and protective pits that are now in the market sufficiently prove that the demand for such has increased and is increasing. An amateur who purposes to provide some kind of glass structure to enlarge the uses and enhance the enjoyments of the garden may well be perplexed at first as to the best mode of procedure. The horticultural papers teem with advertisements of “portable,” “imperishable,” and “multum in parvo” plant houses, and with an almost endless variety of apparatus for heating. It will be found, however, on careful inspection, that in plan and material these do not greatly differ, and that in certain leading particulars they very nearly agree all round, so that a blind man could scarcely go wrong, except, perhaps, as to price, in making choice amongst them. But it is not every one who desires the latest patented invention turned out complete as from a bandbox. In one case an amateur may elect to be his own builder; in another there may be need to give a builder directions, and, perhaps, to watch over the work. One important condition of success, whatever be the mode of procedure, is that the amateur should have a clear idea of the sort of house required to suit the plants he intends to shelter in it.

The great point is to begin well, and the business of the writer of this will be to point out as clearly as possible how the desired end is to be secured, at the least possible expense, and with the greatest possible promise of a successful issue. Matters of fact will concern us chiefly, but matters of opinion will, perhaps, occasionally intrude and be governed always with good intentions, and seasoned with some little knowledge of the subject—sufficient, let us hope, for the purpose.

A disquisition on the nice distinctions that might be drawn between the meanings of such terms as “stove,” “hothouse,” “greenhouse,” and “conservatory,” would serve no useful purpose. They are all plant houses, and depend for their distinctions quite as much on the furnishing and the management as upon structure and fittings. A house may be heated to 80° or 90° to-day for the comfort of orchids, and be called a stove. If we remove the orchids and put pelargoniums in their place, and lower the temperature to 40° or 50°, it becomes a greenhouse. We have but to enlarge it, and introduce camellias and acacias, and give the whole affair a somewhat elegant aspect, and it becomes a conservatory. These several terms are convenient because they refer to different things. But there is no occasion to define them precisely, and we might indeed go wrong were we to attempt the definition.

THE CRIMSON-LEAVED PALM. (Welfia regia.)

Chapter 1

CHAPTER I.

THE CONSTRUCTION OF THE PLANT HOUSE.

Before we begin to construct, we must determine on the site. Now, a bold beginning may be made by the assertion that any site will suit for a plant house, provided the owner will furnish it with plants adapted to the site, and resolve never to make selections without first considering the suitability of the house for their protection. Suppose we have a high damp wall facing north, and wish to cover in the space in front of it with glass for plant-growing. It may be a prudent proceeding to erect there a substantial lean-to, and to construct against the face of the wall inside the house a rockery, and plant the rockery with ferns, and make a lovely scene rich in botanical interest. Or suppose the wall faces south and the position is particularly dry and hot, we may still proceed to cover the space in front with a lean-to, and make a border next the wall for climbers that love sun and a stage in front for a collection of succulents, which never flourish so well as in a “roasting situation.” Or we may plant vines outside and train them up the rafters, and winter all the bedding plants on stages or beds of earth supported by brickwork in the centre. The question of accessibility is of the utmost importance. You will not care to walk far through wind and rain, perhaps, to see the first flowers of the primulas and hyacinths, or to cull bouquets for the friends who will visit you on New Year’s day; nor on a night of keen frost and falling snow will you benefit your health by walking long journeys to stir up the fading fire on which the lives of your pets depend. Think of these things in time, and if your own health does not enter into the question, be not quite oblivious of the health of the gardener. Not only is the position of the house important, but that also of the stoke-hole and furnace, if artificial heat is employed. Where it is possible to place the furnace under cover and in close proximity to a yard where the fuel is stored, the worst of the winter work will be greatly facilitated, and the owner’s purse will be saved. A furnace under cover will afford more heat for your consumption of fuel than one exposed to the wintry blast, and the gardener will not so much dread the task of stoking on a bitter winter night as he will be likely to do in the case where the glare of the fire and the blinding snow assail his eyes at the same time, and his fingers are frozen at the very moment that his face is flushed with looking into the disposition of the burning fuel.

In the construction of a plant house the first matter of importance is to determine the purpose to which it is to be applied. On this will depend the choice of site and aspect, the size of the house, and the extent to which embellishments are to be employed within and without. It will be well for those who study economy to remember that a very plain substantial house, thoroughly adapted for plant culture, will always look respectable, even if it is not decorated like a pavilion or pagoda; and its use will justify it far more satisfactorily than any amount of ornament. There are some grand conservatories in the land in which nothing of a vegetable nature except mildew will thrive, and not a few very humble greenhouses in which plants grow as if by magic, and provide their owners with an endless variety of priceless (though costless) pleasures. The idle man who does not intend to do much in the gardening way may be wise to build himself a roomy and thoroughly substantial conservatory, attached to or very near his dwelling, and furnish it with dracænas, yuccas, agaves, and dasylirions. An ambitious amateur may set his mind upon a block of houses for camellias, heaths, cacti, pelargoniums, and fifty other classes of plants. This one would do well to consult a garden architect, and determine from the first to do the thing well or not at all. But for every one who requires to be accommodated in a peculiar way there will be hundreds who want what is commonly understood as a greenhouse, and the question is. How are they to begin?

A good general advice to all such would be to erect for the present one good span-roofed house, running north and south, in a quite open sunny spot, and have it as large as the purse will allow for the whole thing to be done properly. A large body of air maintains an equable temperature with far less trouble of management than a small body, and hence in a burst of unseasonable heat in spring, or a sudden accession of intense frost in winter, the plants in a large house will be likely to suffer less than plants of the same kinds in a small house, both receiving equal care and attention. By the term “large house” is not to be understood anything extravagant, but a fair roomy structure, with as low a roof as is consistent with the comfort of the cultivator and the size of the plants to be kept in it. If you employ an architect or builder not practically versed in the construction of plant houses to carry out your wishes, you will probably obtain for an extravagant outlay a heavy structure with a lofty roof, in which nothing worth having can be persuaded to grow. Keep the roof down to something like the actual requirements of the plants, for the nearer they are to the glass the better. The lofty roof is one of the most dangerous delusions the beginner in gardening has to guard against when the question arises about the employment of glass.

It must be repeated that the purpose is the matter of first importance. Heaths, geraniums, and camellias will not submit to the same routine of treatment the whole year round, and at the end of that time present equal indications of health and vigour. The heaths and other “hard-wooded” plants usually associated with them require abundance of light and air, and very little warmth in winter. The camellias are not benefited by such a blaze of light or free current of air as the heaths require. The geraniums require more warmth in winter than either, and all the light they can have, with the ventilation so modified that they suffer nothing from the keen winds and freezing showers of early spring. Now, the amateur may be inclined to ask if every class of plants is to have a house to itself? the answer is, No. In a well-built span-roofed house with brick sides, low roof, ample ventilation, and a sufficient service of hot-water pipes, a very miscellaneous assemblage of plants, including some that properly belong to the stove, may be grown by one who has acquired a little experience. But if the amateur has a particular object in view—such, for instance, as to excel in the production of oranges, exotic ferns, the smaller succulents, &c., &c.—then he must provide accommodation in accordance with the requirements of his special pets, and the odd things must take their chance with the help of such little aids as can always be rendered amid adverse circumstances.

Premising that a well-built house of small dimensions is to be preferred to a badly-built house of great extent, it may be well to suggest that it is a very easy matter to lengthen a house, but a rather difficult matter to increase its width. Therefore let the house be wide enough in the first instance, as you may increase its length to any extent that your land and purse will allow. It is well also to select, if possible, a site adapted for a range of houses, should it be some day hence determined to increase the area of glass. We never know what our desires and intentions may be to-morrow or the day after next, and therefore, though it may seem at this moment that the greenhouse in course of erection will suffice for the rest of our lives, we may in a year or so propose to build another, and perhaps yet another, and be compelled to plant them in all sorts of odd corners, where they will be difficult to get at, and, perhaps, impossible to heat them all with one boiler. A systematic and conveniently arranged group of substantial plant houses, however plain and unpretending, are a credit to any garden, but houses of all shapes and sizes, flung all over the place, as if sown by the tempest, are not creditable, and it will be a wonderful thing indeed if they do not prove to be as inefficient as they are inconvenient. A greenhouse in a corner may be snug and useful, but for superior plant-growing there is nothing like a roomy and airy space on a dry subsoil, or, if the situation is low and damp, on a raised and well-drained platform.

The span-roofed house with low pitch of roof is to be preferred for all general purposes; but the lean-to is not to be despised. One advantage of the lean-to is that it turns to good account the shelter and warmth of an existing wall, and in proportion to the covered area is cheaper than a span. It is not an easy matter to grow perfect specimen plants in a lean-to roofed house, and it is not always possible to ventilate such a house with equal ease and efficiency as a span of the same area. But what we lose in one way we gain in another; and a lean-to with long rafters resting on a high and stout wall, with a south aspect, may be made much of as a vinery, and produce first-rate grapes, without the expenditure of so much as a farthing in seven years on artificial heat. The best house we have ever had for substantial work of the useful kind—for keeping and propagating bedders, for the production of grapes and cucumbers, for safe keeping of a number of stove-plants, and for growing tomatoes and melons—was a lean-to with a low roof and walk sunk below the level, the back wall of which was built of old floor-boards placed double, and filled in between with sawdust.

A number of minor improvements have been adopted of late years in the construction of plant houses, the effect of which has been to cheapen them considerably, without impairing, and in some instances actually improving, their efficiency. We say nothing now of patented ventilators and such like, for it occurs to us to mention, first of all, that heavy rafters and sliding lights have become almost obsolete. It is found that side ventilators are in many instances sufficient; but where roof ventilation is required in addition it may be obtained in a much cheaper and more simple way than by the adoption of sliding sashes. Separate squares of glass may be hung on hinges, or narrow-hinged lights may be inserted at intervals. The disuse of heavy rafters, in consequence of their being no longer required to carry sliding lights, allows of the use, throughout, of light sash-bars, carrying larger glass than was ever used for the purpose until within the past few years. Thus a more complete flood of light is obtained than was possible in the old-fashioned houses, while the ventilation is more perfect and far less cumbrous. As for the glass, it should be good English, weighing twenty-one ounces to the square foot. The low-priced Belgian glass is quite unfit for a plant house, however well it may be adapted for sheds and workshops; its numerous specks and bubbles act as burning glasses on the leaves beneath them, and the result is brown spots, holes, and other disfigurements.

There will still arise, perhaps, in the mind of the amateur a number of questions as to the particulars of the construction of the house required. The proper angle of the roof may be one of them, and that is by no means a matter of trifling import. For all general purposes the flatter the roof the better, because it will conduce to the short healthy growth of the plants, if they are placed as near the glass as possible; but there are two serious objections to the adoption of a low angle. It incurs a liability to drip, and it provides a playground for cats in a district where those interesting quadrupeds abound. We once suffered in a frightful manner through the breaking of a pane of glass on a low-roofed house when a party of cats were holding an out-door nocturnal demonstration upon it. They fell in and went mad with fright, and committed such havoc as for the time nearly broke our heart. The amateur in town must protect his interests, if his plant houses have low-angled roofs, by covering them at the distance of a foot from the glass with a “cat proof” wire-net, or adorning the woodwork everywhere with a miniature chevaux de frise. It must be repeated that for general purposes the flatter the roof the better, especially for mixed collections and bedding plants. But if it is requisite to catch the earliest rays of the morning sun in the opening spring, a lean-to with a south-east aspect

“Tom, away; mark the high noises.”—King Lear.

and a steep pitch is to be preferred. Therefore, in building an early vinery a nearly flat roof is of all things to be avoided. In any case, if “doctors disagree,” and the angle of the intended roof becomes a question dangerous to anybody’s peace of mind, it may be settled safely by the figure 45, for that is the angle which affords the best compromise, and most safely subserves a number of purposes.

In fitting the interior we begin with a good paving of red foot-tiles, or something equally good and cheap obtainable in the locality. With mosaic and other fanciful pavements we have nothing to do, for the simple reason that they are costly. There is nothing so good for a stage in summer as large slates, and nothing so good in winter as open wood-work. The houses in which we keep miscellaneous plants have slate stages on each side the centre walk. When affairs are made up for the winter a substantial wood trellis is laid over the slates at a

In fig. 1 is represented one side of a low-roofed span (A), and flat staging near the glass (B). This is a good arrangement. In fig. 2 is represented one side of a steep-roofed span (A), and rising stage (B). This is a very bad arrangement. The central path being in the line A B, the plants are very conveniently placed both for seeing and getting at them, but the lowest are so far from the glass that they must be drawn and blanched and miserable.

The question of material is one of comparatively small importance, because houses of equal value as regards plant production may be secured in either iron or wood, and with either brick or stone or concrete walls. But of necessity there may arise occasions for particular care as to selection of materials, and a few remarks on this part of the subject will be appropriate in this place. To begin with:—at ground line, the question arises, shall we have walls or glass only from head to foot? The Paxtonian houses consist of lights resting in a wooden trough which catches and carries away the rain water, and the thrust of the rafters is received by “chairs” or rests of wood which lodge on blocks of concrete or stone sunk in the ground. Between walls of brick and wood the difference is all in favour of the former as to protective power and duration, but in favour of the latter as to lowness of first cost. As to rafters, those of wood are more perishable than iron, and admit less light. On the other hand, wood is a non-conducting substance, and if a nice comparison were made it would be found that a house with a light iron roof would cost rather more for fuel than a house of the same shape and dimensions with wood rafters, to maintain an equal temperature throughout the winter. But light is life, and iron roofs are adapted to catch the utmost glimmer of the weak daylight of this cloudy clime, and in the case of a structure intended for succulent plants, and such other subjects as need the fullest possible flood of light, iron is certainly to be preferred. In the case of a large conservatory iron is unquestionably superior to wood, and the more so with every advance in elegance of construction.

PARANEPHELIUS UNIFLORUS.

Heating the plant house

CHAPTER II.

HEATING THE PLANT HOUSE.

The heating of plant-houses presents a difficulty proportioned to their size in an inverse geometrical ratio. To put the case in another way, it may be said, that the larger the house or group of houses to be heated the more easily may the desired end be accomplished, but the smaller the house the more difficult the task. In the preceding chapter it is remarked that the atmosphere of a small house is quickly influenced by changes of external temperature; and here it may be added that it is equally soon affected by the action of any kind of heating apparatus. Hence, the amateur who finds his plants hard frozen may light a fire to save their lives, and actually roast them to death in an hour or two, through indiscreet management. Nevertheless, the amateur who has but one small house need not be discouraged by this statement, for it is a part of the ostensible purpose of this book to render aid in this extreme but not uncommon case, as well as in the broader subject of heating in general.

It is of the utmost importance that the mode of heating should be thought of when a plant-house is designed in the first instance, because heat is generated and diffused, in accordance with fixed laws, to which all our arrangements must conform. Thus, if we build a house in a low, swampy position it will be found a difficult matter to give it the benefit of artificial heat by any means whatever, because as heat ascends from the level at which it is produced, it follows that the heat generator or furnace must be placed at a lower level than the house itself, and, in the case of a house in a swamp, the only place for the furnace will be in the water. This is another extreme case for which, so far as the laws of nature permit, we shall endeavour to provide; and it is cited simply for the purpose of impressing the amateur plant-grower with the neces of considering the subject of heating coincidently with the construction of the houses.

The Flue System.—The simplest method of heating is by means of a furnace and brick flue. Every skilled bricklayer knows how to heat a house by this method, but it is well that those who have to pay and take the consequences should know something about it also. It is necessary, in the first place, to provide a sufficiently capacious stoke-hole at the end of the house, or, in the case of a lean-to, behind the back wall. This must be sunk below the level, and there must be a decided rise from the fire to the flue, to enable the draught to overcome the check which the heat encounters in taking the horizontal course of the flue. The simplest arrangement in the case of a lean-to is to take the flue along the front of the house, rising slightly all the way, and terminating in a chimney at the other end. In the case of a span-roofed house it will be desirable to take the flue round the house, rising gently all the way, and terminating in a chimney over the furnace. It will be understood that the necessity of a continuous rise of the flue renders it desirable to place the furnace low enough in the first instance. It is desirable to detach the flue at every point from the floor of the house by means of piers, to allow of a circulation of air around the whole exterior of the flue, and promote a consequent equable distribution of the heat. A small flue of four-inch or six-inch drain-pipes, well cemented at the joints, may suffice for a small house, but what we should consider a good flue would be two feet high and one foot wide, the sides of brickwork, and the top and bottom red foot tiles or slates. A serviceable flue, however, may be made eight inches wide and sixteen inches deep, and in any case the depth should, exceed the width, or it will not draw well. It is a good plan to plaster the flue on the outside, to prevent the escape of smoke, but this is not needed if it is well built, and it certainly does slightly check the communication of heat to the house for the first hour or so after the fire is lighted. A trough for water on the top of the flue should be provided. In some districts tiles, with sunken surfaces, may be obtained for this purpose, but a cistern of zinc or iron is everywhere obtainable. But whoever can construct a flue will find no difficulty in securing an evaporation of water from the top of it. The kind of fuel to be burned will, in some degree, determine the size and material of the flue, for the greater the production of soot, the more frequent the necessity of cleansing, and the smaller the flue in that case, the more troublesome will it be to keep it in order. In any case, however, periodical cleansing must be provided for, and for the flue of average capacity, iron soot doors answer best, or common flagstones may be employed. These should be inserted at the end of every straight line of flue; consequently, wherever the flue turns will be the place for a soot door or something equivalent thereto.

The furnace should be of brick, with double iron doors, and a damper above in the first part of the flue, and a valve in the door of the ashpit for regulating the draught. In determining the dimensions it is well to remember that a comparatively large fire burning slowly is to be preferred to a small fire with a brisk draught. But here, again, the nature of the fuel to be burnt must also be considered, for if it is of a kind that produces little smoke, the opening in front may be dispensed with. It is well, however, to provide for any kind of fuel, and especially for the consumption of the waste fuel of the household, for the cinders the servants “get rid” of will, in many places, sufrice for the preservation of a good collection of plants.

The flue system is now rarely adopted, having been in a great measure superseded by the hot water system, which will next be described. Plenty of good plant growing has been accomplished by means of flues, but they occupy much space, and are liable to crack and emit sulphureous fumes, to the sudden destruction of the plants they are intended to preserve.

The Hot-water System is so generally adopted that there are as many plans of apparatus provided for it as there are days in the year, and, as a matter of course, everybody’s boiler is the best. To a beginner in hothouse practice the variety of boilers must be extremely perplexing, but it will soon be found that they differ but little in essential particulars. In every case there is a furnace beneath a boiler or in the centre of it, and from the boiler proceed iron pipes, laid horizontally around and about the house. The heated water passes out of the top of the boiler into what is called the “flow” pipe, and having traversed the length of the house comes back to the bottom of the boiler by what is called the “return” pipe, and this motion of the water is described as the “circulation.” It is analogous to the circulation of the blood in the body—the fuel is the food, the fire is the life, the boiler is the heart, the flow pipe the aorta, and its ramifications the arteries; the return pipe is the vena cava and its ramifications the veins.

In making a selection of a boiler it is of the utmost importance to ensure greater power than will be required under ordinary circumstances, and in the case of an extensive range of houses there should be two boilers, and they should be in use alternately during periods of a month or so at a time. In case of an accident to one of them—and the best boilers will at times break down—there is another ready for use, and with all