Structure of the Orchid house – 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.


Structure of the Orchid house – 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.

[Illustration: PLATE II 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, rows to suffer neglect.

Structure of the Orchid house (part 2 intro)

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.

Difficulties to Overcome

Some of the difficulties which the cultivator of Orchids has to contend against arise from the fact that his houses have to accommodate plants which have been brought from widely separated countries, or from different altitudes in the same region. They therefore require very different cultural conditions, especially in the matter of temperature.

Consideration of the climatic conditions under which the plants are found growing in their native habitats is very helpful to all engaged in Orchid culture. Many problems have already been worked out by the experience of cultivators, but some of the conclusions have been arrived at only after costly failures. In the early days of Orchid culture, before the advent of the modern Orchid house with its improved methods of ventilation and means for the promotion of humidity, the great mortality among cultivated Orchids was caused by excessive heat and drought. Even at the present day more mischief is done by excessive heat than by cold treatment.

Structure of Orchid Flowers

Most people are familiar with the regular arrangement of the segments of the flowers of Amaryllids and Lilies, with their prominent pistils and anthers. The first stage in the advance of the Orchid family is shown in the Apostasieæ, comprising Apostasia, Neuwiedia and Adactylus, in which the perianth segments are more or less regular and the anthers in some degree prominent, Neuwiedia, with its free stamens and prominent style, appearing at first sight nearer to some of the Amaryllids than to the Orchideæ commonly seen in gardens.

The Cypripedieæ, although so widely separated from other sections as to suggest that in the operations of nature a vast number of connecting types must have become extinct, is the next step, the labellum being formed into a pouch with infolded side lobes. The column has a prominent staminode with two fertile anthers below it, one on each side of the column and behind the stigmatic plate. The upper sepal is frequently the showiest feature in the flower; the lower sepals are joined and arranged behind the lip, whilst the petals extend on each side and vary much in form.

In gardens, the whole of the genus is known as Cypripedium, although the South American species (Selenipedium), having a three-celled ovary, differ widely from the one-celled East Indian and Malayan species, and other sections have such marked and consistent botanical differences as to warrant the botanist in separating them under different sub-generic names. The third section of Orchidæ, the largest family of the Monocotyledons, forms the chief class of Orchids as they are known in gardens. In this class the stamens and style unite into a column, and at the top of the column the pollen masses are situated; these are covered by the anther-cap, and in a cavity is the stigma with its viscid surface to receive the pollen grains.

So diverse and intricate are the forms of the flowers, and especially labellums, that there is little doubt that insect aid is necessary in their natural habitats to bring about pollination. It has been proved by the operations carried out in cross-fertilisation in gardens that no class of plants can be so readily crossed under artificial conditions. It is not necessary here to go further into structural details, as the peculiarities of each section will be remarked on under their different headings. But it may be said that in what are called abnormal flowers, which have perfect stamens and style, can be seen instances suggesting the evolutionary process; these would be more common but for the number of connecting links which have dropped out in the great struggle for existence.

Structure of the Orchid house (part 1 intro)

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.

The Rise And Progress Of Orchid Culture

The first tropical Orchid to flower in the British Isles appears to have been Bletia verecunda (Helleborine americana), figured in Historia Plantorum Rariorum, 1728-1735. It bloomed in 1732 on a plant received by Peter Collinson from the Bahamas in the previous year.

In succession to this appeared Cypripedium spectabile and one or two other North American Cypripediums; Vanilla aromatica, and a few other species, chiefly terrestrial Orchids.

In 1789 Aiton’s Hortus Kewensis enumerated fifteen species of exotic Orchids as being in cultivation at Kew, the tropical species being Bletia verecunda, Epidendrum fragrans, Epidendrum cochleatum, and Phaius grandifolius.

At the end of the eighteenth century about fifty exotic species were recorded. At that time most of the Orchids were imported only to perish as a consequence of the unsuitable conditions in which they were grown. The plants were potted in the most unlikely materials, such as decayed wood, sawdust, loam, tanner’s bark, or any other material which the cultivator thought would be useful in preventing the excessive mortality among his plants; but in all cases the chances of success were discounted by the plants being placed near hot flues, or plunged in tan or bark beds. It was thought that a great success had been attained if a plant bloomed once before it died.

The year 1800 may be said to be the real starting-point of rational Orchid culture, although, even in the earlier part of the nineteenth century, the old traditions still hindered progress. In 1800 Aërides odoratum was introduced, this being the first East Indian Orchid cultivated in this country. In 1817 Sir Joseph Banks brought about the cultivation of epiphytal Orchids in light, wicker baskets which were suspended in the Orchid house or stove; this is one of the most noteworthy events in the early history of Orchid cultivation.

In 1818 Cattleya labiata appeared, and about the same time Cypripedium insigne, which has now two or three hundred varieties that enthusiasts consider sufficiently distinct to bear varietal names. Disa grandiflora and Oncidium Papilio appeared in 1825, when about 180 species of tropical Orchids were in cultivation in the Horticultural Society’s Gardens. This Society gave a great impetus to Orchid culture by sending out collectors into distant lands, and Dr. Lindley, whilst Editor of the Gardeners’ Chronicle, played a no less important part in studying and recording the species as they were received in this country. The interest in Orchid importing gradually spread, and from the time when Alan Cunningham sent home Australian Orchids in 1835 the interest has never flagged, the famous Orchid collectors, Lobb, Gardner, Skinner, Hartweg, Gibson, and others, sending consignments from time to time from various parts of the world.

The first attempts to grow Orchids in a reasonably low temperature were made in the first half of the nineteenth century, one of the first to grasp the truth in this direction being Joseph Cooper, who was gardener to Earl Fitzwilliam at Wentworth. But a considerable time elapsed before the more rational treatment, which meant less artificial heat and more ventilation, became general. The culture was further improved by the introduction of the hot-water system of heating Orchid houses, a method which is now almost perfect and has done more to further Orchid-growing than anything else.

The spread of information respecting the climatic conditions of the countries in which the plants were collected also helped cultivators in this country, and the articles published in the Gardeners’ Chronicle in 1851 by the late B. S. Williams, and subsequent articles by other experts, were of great service.

The latter half of the nineteenth century was the most important era in the development of Orchid cultivation. A remarkable feature was the beginning of that industry which has now attained such widespread popularity, namely, the raising of hybrid Orchids from seed. The first hybrid Orchid, Calanthe × Dominyi (obtained from a cross between C. furcata and C. Masuca), flowered with Messrs. James Veitch & Sons in October 1856. The same firm subsequently produced many fine hybrid Calanthes, Phalanopsis, Cattleyas, Lælias, and Læliocattleyas. Many of these are now standard garden plants, whilst the work of hybridising and raising hybrid Orchids has become general.

Another notable event in Orchid culture during the period mentioned was the commencement of the Cool-house or Odontoglossum Section of Orchid Culture. In 1863, Weir, Blunt, and Schlim went to New Granada in search of Odontoglossums, and they were successful in introducing plants of Odontoglossum crispum (Alexandræ), collected above Bogota. These collectors also contributed to our knowledge of the proper methods of cultivating cool Orchids.

So things have gone on until our own days. Orchids hold one of the most important places in gardens, and such genera as Odontoglossums and Cypripediums are so popular that they are cultivated on an extensive scale even by many who do not care to grow a general collection of Orchids.