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° to 10° 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, East Indian. | Cattleya or Intermediate House. | Cool or 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 |