Where ever it is (and whoever its owner may be) a greenhouse is bound to be one of three things:
it is a structure wherein certain plants are grown for the purpose of securing their flowers or fruit in other words,
a flower or fruit factory; or it is a general laboratory attached to the garden, where plants are
propagated, nursed to health when sick, and wintered if tender, and grown for use in the dwelling; or it is an indoor garden with all that the term implies of a place in which to loiter as well as to potter about a place of real charm and beauty as well as a suitable home for the plants which grow therein.
In this last character it may be more a conservatory than a greenhouse, although a conservatory is not, strictly speaking, to be regarded in the same way as a greenhouse, since it affords a home only for plants grown elsewhere and brought into it for show.
Some of the elaborate winter gardens are of this type as well, being planned to be continually filled from growing houses built for the purpose. But the garden under glass is not of necessity carried on in this double fashion since plants will grow in it even as they grow out of doors or in the outdoor summer garden if it is planned to that end. For the fullest enjoyment of a garden enthusiast there is no doubt that this is the better choice, since the varied operations of both gardens may then be carried on supplementally and a variety of effects be enjoyed-not identical with each other, by any means, but along parallel lines.
Actually there is a greenhouse for every kind of place and person. And there is sound reason for every kind of place and person having one; for a greenhouse is, not in any sense of the word an extravagance, save as it is made one in the manner of handling. To the large place it is an essential adjunct of both the ornamental and practical gardens; to the medium sized establishment it is a valuable addition to these; and to the tiny plot of ground around a suburban home it is practically a multiplication of opportunity by two at any rate, if not by four or five. And going one step further it is a garden where there is no ground at all since the roof of a city residence will furnish an ideal site. Similarly, it may require the time of several men, or only one; or it may be its enviable owner’s own particular hobby, sharing the heat of his house and not dependent, therefore, upon separate stoking; and occupying him in his off hours. If it is to be cared for in this way, however, it is well to say at once that it should be small; for, like a garden, a greenhouse may easily be large enough to get out of hand and never be entered in again!
The kind of greenhouse, which is decided upon, will of course govern its location very largely. The purely working glass, fiberglass or ploycarbonate house should be placed where its relation to the garden that it serves makes for the highest degree of efficiency in handling the plants as they go in or come out; and apart from this consideration there is actually no other, as far as the building itself is concerned, aside from the vitalness of its freedom from shade of trees or near by buildings. It must have unhindered light and sunshine.
With regard to the garden’s appearance and design, however, the location of a building of such aggressive character is of tremendous consequence, and demands the most thoughtful care. For improperly placed it may irreparably mar the entire garden picture; and yet, given proper thought, can be a most attractive acquisition.
Fitting it to the Place
Much study is now being given to greenhouse design from an architectural as well as from a practical standpoint, and structures that are pleasing in appearance have been developed fit to assume a place in the garden scheme. So it is no longer necessary to hide even the strictly utilitarian building. But unless the greenhouse can be made an acceptable unit of the general scheme and not obviously an afterthought it is better not to let it appear at all, but have it obscured by proper planting.
On small suburban grounds it must of course take a relatively prominent place and may become in effect an addition to the home. In this connection a transition from dwelling to greenhouse by means of a glass corridor will usually solve the problem of their relation to each other by separating them enough to allow each its individuality; which is far better than any attempt to weld them into a single unit. As a matter of fact, they cannot be so welded, and the effort actually to bring them together may be to the detriment of both.
Sunshine to the fullest degree is of course requisite. Choose a site, therefore, where this is insured and permanently so. The angle of sunlight incidence at noon on the shortest day of the year is 22 degrees; therefore the greenhouse must be kept beyond this angle’s distance from anything on its south side. Be careful also to choose a well drained spot and a comparatively high one, for poor drainage and damp conditions generally are breeders of mildew; and with this handicap in surroundings it is practically impossible to maintain the proper atmospheric conditions under the glass.
These conditions being observed the points of the compass may be disregarded generally, though if fruits on trellises are to be grown the trellis should run north and south. This will mean that where it is lengthwise the house itself must run north and south, but where it is crosswise the house will run east and west, bringing the trellis north and south.
Its Shape and the Frame
The type of frame most generally in use today is the modified curved eave, whether the structure is an even span or a lean-to. It has very attractive rooflines, gives a maximum of light to the plants, and allows ample side ventilation above the benches. As to the form of the house there is no question about the superiority of the even span; and there is seldom any good reason for building anything else. The lean-to may of course be the only thing that will fit in certain restricted places, but if it can possibly be avoided it should be. Even when the greenhouse is to be attached to the garage or wing of some existing building, it may perfectly well be even span and stand end on instead of being only half a house with excessive roof height standing side on. Plants growing in a lean to are bound to ” draw ” or lean strongly in one direction because of the uneven distribution of light, and the difficulty of proper ventilation.
The all aluminum frame house is naturally the most expensive to build, but as maintenance costs practically nothing and repairs are nil, its first cost is soon more than compensated; and thereafter it is daily a gain over the hoop house. Greenhouse glass must be the pure white variety, and here again, as with the material of the frame, quality is economy and the “double thicks” glass, which weighs twenty-two ounces to the square foot, should be used if possible. Glass that is still heavier is often used in the modern houses where the framework calls for large-size sheets. Ground glass has been used for exotics, but in general it is better to use the clear glass and depend for shade when it is desired upon light fabric drawn across the span. Summer shade for the roof must be provided for, and there has been nothing better devised than a rolling slat screen. Commercial houses of course freely practice White washing or some such brush-applied shading material, especially, but it is unsightly and does not, moreover, allow for the entrance of the sun when you wish it to enter. In practice the wash is put on the outside in early summer and the weather removes it by late fall.
Keeping Things Warm
The very heart and soul of the greenhouse is its heating system. It will make no difference how perfect its appointments and its construction, nor how skillful its attendant, nor how beautifully it is planned, if its heating system falls short. It is then a dead thing as dead as a tomb! In greenhouse heating, as in all others, it is desirable to provide for greater capacity than the figures show will be actually needed, since it is always more economical to run a fire in check than under draft. Then, too, there may come, once in a decade or so, a season of untoward severity, during which only the excess heat that has been figured on will save the night, if not the day.
Unquestionably it is a wonderful idea, this greenhouse one of turning summer into winter and temperate regions into tropical and converting. Sunshine into flowers or luscious fruits, generally right against the calendar. Yet it is timely to remember right here and now that this is not exactly what happens in a greenhouse. As a matter of fact, gardening under glass is not simply protected from the weather gardening, wherein the work is carried on with the same materials as are used out of doors; but rather it is gardening with very special materials in most cases, as well as under highly artificial conditions. In the greenhouse three of the four factors of garden work are controlled, but the fourth is quite beyond control. Temperature, soil, and moisture are adjusted as delicately as necessity demands; but light still remains outside the reach of all our cunning and what is more, light is diminished always, however cleverly we may build, quite apart from the fact that normally light diminishes greatly in winter, just when we expect the greenhouse to be most active! So that while we control the three and increase these however we will, we diminish the fourth in spite of everything; and create, therefore, something quite different from any outdoor conditions.
A New World Opens up
Realize, therefore, that you do not need to confine yourself to the plants of our outdoor gardens that we may bring in and establish in gardens under glass-but also a whole world of plants of another character (many the result of careful and long breeding or selection) which must be as carefully studied as new worlds always are, in order that their requirements shall be understood and met. Moreover, these plants come from widely different places, and require a great deal more than simply protection from cold to enable them to grow so far from their native clime and condition; and they are not all of the same taste and temperament, either-not by any means. Some like much moisture and heat, others need little of either, and still others come between and will be satisfied with no extremes. This can be easily met by a careful selection, according to the proposed temperature of your greenhouse; or else by having a series of ” compartments ” run at the different temperatures to meet these varying needs. Of course your own common sense tells you not to expect to grow everything that may be fancied in your greenhouse, simply because it affords protection to things that are not hardy in your latitude. You will attempt growing only what you make definite provision for when you are building.