Culture in the mushroom-house being the most practised, and, on the whole, the most important phase of the subject, we will first treat of it. And first of the mushroom-house itself. Its construction is very simple: the conditions to be obtained are equable temperature, secured by thick or hollow walls and by a double roof. Figure 1 shows a house designed for me by Mr. Ormson, the well-known horticultural builder.

It is situated at the back of the hothouses, where a flow and return pipe can be run through for artificial heat. The shelves for making the beds upon are of slate 1½ in. thick, or of stone 2½ in. thick, built into the walls, and into brick piers built in cement. Upright slates, to slide in grooves, are placed along the front of the shelves to keep the beds in.

The floor may be of paving tiles, or bricks, laid on concrete: a skylight or two may be fixed in the roof, for the purpose of admitting a little light, and air when necessary. The engraving (fig. 2), shows a house of this description, 12 feet wide by 20 feet long, inside measure, but, of course, the length may be extended as circumstances may require.

As it is of importance in mushroom-growing that the air of the house should be kept moderately moist, the underside of a slate or tile roof should be lathed and plastered.

Figure 3 represents a mushroom-house suitable for people of small means, or those who cannot adopt plan No. 1. It is designed with a view to growing mushrooms during the greater part of the year, without the aid of artificial heat. To this end it is constructed in such a way as not to be affected by changes of the external temperature, as will be seen by the engraving. The walls are hollow, and banked round with the soil excavated from the interior. The roof is thatched with reeds, and the ends stud-work, lined inside with boards, and outside with split larch poles: the cavity to be filled with sawdust or cut straw; a small diamond-shaped ventilator, hung on pivots, to be fixed in each end. The floor may be of concrete, or burnt clay well rammed; and the beds are retained in their place by boards nailed to good oak posts. Care should be taken to put in efficient drains, so that no stagnant damp may exist about the building.

Though the preceding cuts show how we may best attain our object, a few more illustrations of mushroom-houses are desirable here. Figures 5 and 6 exhibit the plan of the mushroom-houses at Frogmore, obligingly communicated by Mr. Rose.

It need hardly be said that in such large mushroom-houses rhubarb and sea-kale may be easily forced, and barbe de capucin, endive, &c. blanched.

A small hot-water apparatus, with a 3-inch flow and return pipe, affords the best means of heating a mushroom-house which is not so situated that it may be heated from the boilers of adjacent hothouses. The best position for the mushroom-house is against a north wall. The usual precautions for guarding against damp walls and floor should be adopted in the case of the mushroom-house, and the walls should be hollow.

Forsyth’s mushroom-house is described by the designer in Loudon’s Gardener’s Magazine. Fig. 7 is a transverse section, showing the arches under and over the beds, the thoroughfare a is the middle, and the position of the hot-water pipes, c; b is an open shed and general workshop, the receptacle of everything requiring protection, and too clumsy to be otherwise housed.

A shed of this description is an indispensable adjunct to every well-ordered garden, and in the present case it serves as a roof to the mushroom-house. In the centre of each vault, shown in fig. 7, a circular ventilator, d, 9 in. in diameter, should be made, having a stone and cast-iron stopper, with a folding ring. The whole roof of the mushroom-house is covered over with pavement, which at the same time forms the floor of the shed above. Mr. Forsyth objects to cast-iron shelves “on account of the rust, and to slate shelves, as being cold and damp, and therefore not suitable to the purpose;” but he knows of no objection to shelves built of bricks and mortar, kerbed with hewn stone 3 in. wide, and clamped together with lead.

The annexed diagrams (figs. 8 and 9) exhibit the mushroom-houses used at Stoke Place, both for summer and winter use, as described by Macintosh in the “Book of the Garden.” “Of course the former is not heated; the latter is, by 4-inch hot-water pipes, which are brought from a boiler constructed to heat at the same time a range of pits for pines, melons, &c., 89 feet long and 7 feet wide. The shelves are close-bottomed to prevent the beds from drying too rapidly, and to require less watering, which Mr. Patrick thinks a very important precaution in mushroom culture. Ventilation is effected by a slide in the door, and a wooden trunk up through the arch and roof, with a slide in it also. We do not exactly see the motive of Mr. Patrick, whom we have long known and esteemed as one of the best gardeners in England, in adopting the span roof over this house, as, from its situation behind the garden wall, a lean-to roof would have been cheaper and carried off the rain-water better. It is rather a novel, but still a good plan, to have the inner roof constructed of a brick arch, as it will of course save the outer one from decay, to which all mushroom-house roofs are liable more than any other kind of garden building. This house struck us at first sight as very complete, excepting in breadth. We should increase it to 9 feet—that is, 3 feet for the breadth of the beds on each side, and the same for the footpath, which at present is inconveniently narrow.”

The Russian mushroom-house (fig. 10) is thus described by Mr. Oldacre, in the Horticultural Society’s Transactions, vol. ii. first series. “The outside walls should be 8½ feet high for four heights of beds, and 6½ for three heights, and 10 feet wide inside the walls. This is the most convenient width, as it admits of shelves 3½ feet wide on each side, and affords a space through the middle of the house 3 feet wide, for a double flue and a walk upon it.” Hot-water pipes were not in use when this house was erected. “The walls should be 9 inches thick, and the length of the house as may be judged necessary. When the outside of the house is built, place a ceiling over it (as high as the top of the walls) of boards 1 inch thick, and plaster it on the upper side with road sand well wrought together, 1 inch thick, (this will be found superior to lime), leaving square trunks, f, in the ceiling 9 inches in width, up the middle of the house, at 6 feet distance from each other, with slides, s, under them, to admit and take off air when necessary. This being done, erect two single-brick walls, v v, each five bricks high, at the distance of 3½ feet from the outside walls, to hold up the sides of the lower beds, a a, and form one side of the air-flue, t u t u, leaving 3 feet up the middle, t x t, of the house for the floor. Upon these walls, v v, lay planks, t u, 4½ inches wide and 3 inches thick, in which to mortise the standards, t k, which support the shelves. These standards should be 3½ inches square, and placed 4 feet 6 inches asunder, and fastened at the top to the ceiling joists. When the standards are set up, fix the cross-bearers, i n i n, that are to support the shelves, o o, mortising one end of each into the standards, n, the other into the walls, i. The first set of bearers should be 2 feet from the floor, and each succeeding set 2 feet from that below it. Having thus fixed the uprights, t k, and bearers, i n, at such a height as the building will admit, proceed to form the shelves, o o, with boards 1½ inches thick, observing to place a board, d d, 8 inches broad and 1 inch thick, in the front of each shelf, to support the front of the beds. Fasten this board on the outside standards, that the width of the beds may not be diminished. The shelves being completed, the next thing to be done is the construction of the flue (p in section), which should commence at the end of the house next to the door, run parallel to the shelves all the length of the house, and return back to the fireplace, where the chimney should be built; the sides of the flue inside to be of the height of four bricks laid flatways, and 6 inches wide, which will make the width of the flues 15 inches from outside to outside, and leave a cavity, t u, on each side betwixt the flue and the walls that are under the shelves, and one, x y, up the middle, betwixt the flues, 2 inches wide, to admit the heat into the house from the sides of the flues.” The introduction of this form of house by Mr. Oldacre has led to much improvement in our mushroom culture. The first house of this kind erected in England, was built at Shipley, near Derby, in the garden of E. M. Mundy, Esq., by the father of Mr. W. P. Ayres, whose name will be found frequently mentioned in this work. There brick arches were formed for the shelves, and though built more than half a century ago, the house is still in good condition.

Although slate is generally used for the shelves, the adoption of cast-iron gratings for this purpose is well worth a trial, as by this means we may be enabled to cut mushrooms from the under as well as the upper side of the bed.