CHAPTER IV. Structure of the Orchid House

STRUCTURE OF THE ORCHID HOUSE

So far as the improvements in present-day Orchid houses are concerned, these are not due to the imagination of the horticultural builder, but to the experience of the Orchid grower. It is owing to him that the old-time glass sides, with their hinged ventilators on a level with the plants, and many other harmful arrangements, have been abandoned. Moderately low, span-roofed houses, extending north and south for preference--although the aspect does not seem to be of vital importance--are the best, the sides being wholly of brick, and also the ends of all but the large houses, in which the upper part may be formed of wood and glass.

The top ventilation should be admitted through ventilators placed at the highest point of the ridge, and they are usually worked by a continuous system manipulated at one end. The lower ventilators should be small ones fixed in the brick-work at the sides of the house, and they may be arranged to be regulated from the outside, or by means of rods attached to the flaps on the inside and reaching to the path, being carried beneath the staging. The natural earth is the best base for an Orchid house, and open wood-work trellises placed on the natural earth are far preferable to tiled paths, therefore their use is strongly recommended. Beneath the central stage, from end to end, deep tanks with cemented interior should be provided, because rain-water is essential for watering the plants. To create a good appearance, narrow, ornamental rockeries may be arranged at the edge of the side staging and beneath it, and in any part of the basement available. These should be planted with Begonias, Tradescantias, such ferns as are not likely to be attacked by thrips, Selaginellas, Fittonias, and Ficus repens, which are not liable to attacks from insects, whilst their presence tends to preserve a healthy atmosphere in the house.

The rockeries beneath the staging should not be built high enough to obstruct the passage of the heat from the hot-water piping, a rise of one foot from the ground level being sufficient.

In the warm-house, Eucharis grandiflora and other species of Eucharis; Hymenocallis and Pancratiums, thrive and bloom well beneath the staging. The inside of the roof should be wired for suspending baskets containing Orchids, and this should be done before the plants are placed in the house.

As regards the form of structure, comparatively low, span-roofed houses, with brick sides reaching to the eaves, and no side glass, are the best, the ends being of brick up to the height of the side walls, the remaining part running up to the ridge, in all but very small houses, being formed of wood and glass. If several houses are built, spaces should be left between each house, and no two or more houses should be built with partition walls, for these prevent the necessary side ventilation. A house of 100 feet or so in length should have a division midway in its length, which for some purposes gives the advantages of two houses. Pitch-pine or teak, being durable, are good woods for the wood-work, and, in any case, the use of cheap, soft timber should be avoided. In glazing, only a thin bedding of putty should be used, and the glass should be bradded on the upper side, as top putty when decaying or on becoming loose is worse than useless, and tends seriously to foul the water in the cisterns. Span-roofed houses 12 feet to 15 feet wide, and of proportionate elevation, are suitable for ordinary Orchids, but if specimen plants are desired a loftier house will be necessary.

A range of houses should, if possible, be connected at the end which is most exposed to the north and north-east winds by a corridor or covered structure, in which the potting-shed stores and entrance to the boiler hold should be arranged. The greatest care must be taken that no fumes from the heating apparatus can find their way into either the corridor, potting-sheds, or plant-houses, or the plants will suffer the worst consequences. Safety can easily be assured by thoroughly ventilating the stoke-hold and making the partition between the corridor or offices and the stoke-hold as air-tight as possible.

The wood-work, when of pitch-pine or other hard wood planed smooth, may be oiled or varnished, painting being undesirable for new houses. In course of time, however, painting has to be resorted to, and it is one of the most trying operations about the Orchid houses. Great care has to be taken to obtain a reliable quality of paint that will not harm the plants, and to keep the house vacant for as long a time as possible for the gases from the paint to escape. After the plants are returned to the house some ventilation must be maintained day and night for a time. Tar should not be used inside an Orchid house for any purpose.

THE STAGING

The staging must be arranged according to the width of the house. Narrow houses may be provided with a stage on each side and a path through the centre. Other structures of sufficient width should be furnished with a side stage measuring 4 feet to 4 feet 6 inches in width, and a central stage on a somewhat higher level, and rising in steps to the middle and highest point.

MILTONIA VEXILLARIA

"EMPRESS AUGUSTA VICTORIA"

(This specimen, cultivated from a single growth, bore 126 flowers.)]

Iron frame-work is the best, because it is clean and almost indestructible. The uprights resting on the floor should be fixed in metal saucers, which, if kept filled with water, offer great obstacles to insects ascending from the floor. The open wood-work resting on the iron frames, and on which the plants are to stand, should be of teak or pitch-pine, and arranged trellis-like. For some years past it has been the practice to have a close, moisture-holding stage of slate, or tiles, beneath the upper and open wood-work stage. It was an invention of my own when adapting an ordinary plant-house with a slate stage to receive one of the earliest importations of Odontoglossum crispum. The existing slate stage was made water-tight at the joints, and a fillet of cement was run along the back; the surface was then covered with clean shingle, and home-made trellises, raised on bricks in three levels, were placed along the close staging to receive the plants. It proved a great success, and in the same house the small, bottom ventilators, the first of their kind, but which have now become general, were an equally good innovation. At that time, and for many years afterwards, the flooring of Orchid houses was sealed by concrete or hard tiles, and the moisture-holding lower stage was necessary to give a reasonable amount of evaporating surface. More recently it has occurred to many of us that a moisture-giving surface might be obtained from the natural earth, if the earth was left either in its natural state or was given a coating of coke-breeze or similar porous material, and trellises used for the paths. In a similar way provision had to be made for the second object of the close stage, namely, the checking of the direct upward heat from the hot-water pipes. This has been done very effectively in some gardens by arranging a much less elaborate and costly means than the full, close staging generally in use. An iron frame is placed midway between the hot-water pipes and the staging on which the plants rest; a shelf of corrugated iron, slate, or tiles, extends from the back to about half the width of the side staging, its inner edge being about midway in the space beneath the staging, and an inch or so of space is left between the back of the shelf and the wall of the house to allow some of the heat from the pipes to pass that way, the greater part being diverted towards the middle of the house by the intervention of the shelf which is covered with turf or some other moisture-holding material. This is kept continually moist by frequent syringings during the warm season, when plenty of moisture in the air is required.

In arranging new houses having the natural earth for a floor, this plan is less expensive and altogether preferable to the formal, close staging of full width, which, however, should still be retained in adapting ordinary plant-houses already provided with a tiled or cemented base, unless it is convenient to remove the tiles and restore the natural earth surface. In arranging the staging, one essential object has to be kept in view, namely, that no part of it shall be out of easy reach; for very wide stages are apt to cause the plants in the back rows to suffer neglect.

METHOD OF HEATING

In these progressive times it is not well to lay down hard-and-fast rules with regard to the best type of appliance. It should, however, be urged that every Orchid house ought to be heated with hot water, and, that in all cases 4-inch piping should be used, the radiation of heat from that size being much more gentle and equal than from smaller pipes. Bottom heat by means of piping under closed-in beds of cocoa-nut fibre, or any other material, is bad, although, in a very slight degree, some arrangement of the kind may be of assistance in the house devoted to raising seedlings. If it is used, an outlet must be provided for the inevitable moisture thus raised so that it will not condense and fall on the plants.

For small houses or blocks of houses, the old saddle boiler in some form is all that can be desired; and there are several forms of slow-combustion boilers which may be set almost on the surface of the ground outside the house, and these are satisfactory. For blocks of houses the English form of sectional boiler is one of the very best; in large blocks duplicate sets of this pattern, or any other type that may be selected, should be set down, as it provides means of heating the houses if the ordinary boiler happens to fail. It is always better to provide more power than may appear absolutely necessary, and work it at low pressure, than to have barely sufficient power and work it hard during severe weather, as the heat diffused in the latter case is harmful.

Before deciding on the means of heating to be employed, it would be well to pay a visit to some of the collections noted for the excellent condition of their plants, and inspect the appliances and their arrangement. Most Orchid growers, whether in private establishments or nurseries, are willing to assist amateurs in these matters. When the apparatus has been got into working order, tests should be made to ensure an equal distribution of the heat from the piping. If a draught of hot air to any part of the house from beneath the staging is observed, it is a good plan to build up openly-laid screens or brick walls 4-1/2 inches thick, the layers of brick being placed so that there is half the length of the brick opening between each brick and the next to it. Where there is a sufficient command of heat, these openly-laid brick walls, without mortar, built up below the side staging and running parallel with the edge of it, if they are syringed frequently, assist materially in preserving a healthy moisture in the house.

TEMPERATURE

One of the most important matters in Orchid cultivation is to see that a lower temperature is maintained at night than in the day. Nothing is more injurious to the plants than to be kept in a high temperature at night, nor is anything more contrary to natural conditions. All who have travelled in the countries from whence Orchids have been imported testify to the great difference between the temperature during the day and that experienced at night, the difference in some parts being that between an excessively hot day and a chilly night and early morning. These cool conditions at night are absolutely necessary for the well-being of the plants, and in their absence the plants suffer as do human beings during the progress of a heat-wave, which often kills many people. Therefore it must be urged that at night the temperature must be from 5 deg. to 10 deg. Fahrenheit lower than the day temperatures. This condition is difficult to get during hot weather, but it is necessary. Although a scale of temperatures throughout the year must not be taken to mean that a little more heat may not be allowed occasionally--as, for instance, by sun-heat, which is beneficial--nevertheless it is better to have a scale to form a basis, and especially to emphasise the lower temperature at night.

~Table of Temperatures for Orchid Houses~

----------------------------------------------------------------------- Months. | Warm House, | Cattleya or | Cool or | | East Indian. | Intermediate House.| Odontoglossum House.| -----------|---------------|--------------------|---------------------- | Day. | Night.| Day. | Night. | Day. | Night. January | 65-70 | 60 | 60-65 | 55 | 50-55 | 45 February | 65-70 | 60 | 60-65 | 55 | 50-55 | 45 March | 65-70 | 60 | 60-65 | 55 | 55-60 | 50 April | 65-70 | 60 | 60-65 | 55 | 55-60 | 50 May | 70-75 | 65 | 65-70 | 60 | 60-65 | 55 June | 75-80 | 65 | 70-75 | 60 | 60-65 | 55 July | 75-85 | 65 | 70-80 | 65 | 60-70 | 55 August | 75-85 | 65 | 70-80 | 65 | 60-70 | 55 September | 75-80 | 65 | 70-75 | 60 | 60-65 | 55 October | 70-75 | 65 | 65-70 | 60 | 60-65 | 55 November | 65-70 | 60 | 60-65 | 55 | 55-60 | 50 December | 65-70 | 60 | 60-65 | 55 | 50-55 | 45 -----------------------------------------------------------------------

Degrees Fahrenheit. The higher day temperature should be obtained by sun-heat when possible.

Further remarks on this and other details will be found under the headings of the different genera, but it will be better now to state in general terms that during the season of active growth any reasonably high temperature by sun-heat, secured by keeping the house tolerably close and well shaded, greatly benefits the plants. This is specially noticeable where batches of Dendrobium nobile, D. Wardianum, and other deciduous Dendrobiums are grown. Those who grow them best allow the house containing the plants to become very warm; they remove the shading early in the afternoon in order to let the plants get the longest duration of light possible, and they keep the house very moist until the evening.

THE SINGLE ORCHID HOUSE

It is doubtful whether the owner of a large collection of Orchids gets a greater amount of pleasure than the beginner starting with but one Orchid house, provided the owner of the single structure is careful in selecting his plants.

In cases where only one Orchid house is possible, and a more or less general collection of plants is desired, that house should be heated as an intermediate house. The single Orchid house has often been the starting-point of more extensive culture. It is generally commenced by utilising an existing plant-house, in some cases, unfortunately, without making the necessary preparation for the new occupants.

When it has been decided to adapt a house for Orchids, the proper course is to clear the house of its contents, thoroughly overhaul the interior fittings, such as staging, &c., and make any alterations necessary. The heating apparatus should be regulated, and, above all, the best possible provision must be made for catching and storing rain-water, even if this necessitates the providing of a brick and cement tank beneath the staging.

If the existing floor in the house is of concrete or tiles, or any similar material, it must be removed, leaving the natural earth for the surface of the basement, and providing a wood-trellis for walking on in spaces between the stages. Let the house be thoroughly cleansed and painted, and after a short time has elapsed it will be ready to receive the plants.

In such a house heated as a cool, intermediate house, with a minimum temperature of 50 deg. to 60 deg. Fahr. in winter, a large number of showy Orchids can be grown successfully. Those species which require great heat should be carefully avoided, for, although cool-house Orchids are easily managed in a house warmer than is necessary for them, the hot-house kinds usually fail in a temperature which is too low to allow of their making growth under favourable conditions. In such an intermediate house the Odontoglossums, Masdevallias and other favourite cool-house Orchids can be grown successfully, if arranged in the cooler part of the house and carefully watered. The Cattleyas, Laelias, and the garden hybrids should be placed on the staging in the middle of the house, well up to the light; the Brazilian Oncidiums, Sophronitis grandiflora, and Stanhopeas should be suspended from the roof of the house, but in such positions as will avoid placing them over the plants on the side staging. The Odontoglossums and Cochliodas may be accommodated on the side staging in the cooler and moister part of the house. In such a house all the varieties of Cypripedium insigne, C. Spicerianum, C. Charlesworthii, and all the green-leafed section known as Selenipediums, will thrive admirably, and a very large selection of other showy Orchids, including Zygopetalums; but again I would say that species which are usually regarded as warm-house Orchids must be rejected.

SHADING

It should be distinctly understood that every Orchid house needs to be fitted with proper means of shading, extending over the whole roof and removable when necessary. Some cultivators think they meet the case by providing shading only on the sunny side, or by painting the glass with some kind of preparation more or less in the nature of whitewash. Such preparations should never be used, because, when this is once placed on the glass, the shade, such as it is, is there in dull as well as bright weather, in the night time as well as the day, and for the greater part of the time, especially in dull seasons, it obstructs light which is necessary for the proper development of the plants. Another important objection to their use is that shading given by these washes wears off and leaves the plants exposed to the full sunlight. The substance is washed off by the rains and carried into the rain-water tanks, thus causing injuries to the plants watered with the polluted water, and rendering unsightly the foliage moistened with it.

Proper blinds running on iron or wooden supports, raising them well above the glass of the roof, are absolutely necessary. Lath roller blinds are excellent for shading, being durable, clean, and easily let down and drawn up.

Light canvas or scrim shading fixed to roller blinds answers the purpose well, but care should be taken not to employ heavy, closely woven canvas. Too great attention cannot be paid to the working of these blinds, for they must never be down except when required for protection against the sun's rays, and they must be drawn up during dull intervals.

The blinds are useful also during severe winters as a protection against excessive cold at nights, and in this particular the lath roller blinds are the best, and may be left in position where they are likely to be required for this purpose.

When canvas blinds are used during the summer and removed in late autumn, care should be taken to have them perfectly dry before they are stored for the winter in some dry place, or they will be useless when they are required for placing in position the following spring.