Fig. 9. Ground Plan of Mrs. Osborne's Mushroom House.
The roof should be double and always sloping,—never flat. The hoar frost that appears in severe weather inside a single roof is likely to melt as the heat of the day increases, and this cold drip falling upon the beds below is very prejudicial to the mushroom crop. A double roof saves the beds from this drip, and it also renders the house warmer, and less fire is needed to maintain the requisite temperature. One might think that a single roof like that of a dwelling house, and then a flat ceiling under it, would be equivalent to a double sloping roof, but it is not. The moisture arising from the interior of the house condenses upon the flat ceiling, and the water, having no way of running off, drips down upon the beds. With a sloping ceiling or inside roof the water runs down the ceiling to the walls. A very pointed example of this may be seen in Mrs. C. J. Osborne's excellent mushroom house at Mamaroneck, N. Y. It had been built in the most substantial manner, with a sloping roof and a flat ceiling under the roof, but so much annoyance was caused by the drip falling from it upon the beds below that her gardener had the flat ceiling removed and a sloping one built instead, and now it works splendidly, and a few months ago I saw as fine a crop of mushrooms in that house as one could wish to look at.
The interior arrangement of the mushroom house may resemble that of the mushroom cellar. Beds may be made alongside of the walls and, if there is room, also along the middle of the house, and shelves erected in the same way as in the cellar. But in the case of cold, thin outside walls, the shelf-beds should not be built close against them, but instead boxed off about two inches from the walls, so as to remove the beds from the chilling touch of the wall in winter. Economy may suggest the advisability of high mushroom houses, so that one may be able to build one shelf above another, until the shelves are two, three, or four deep. But this is a mistake. The artificial heat required to maintain a temperature of 55° in midwinter in a house built high above ground would be too parching and unsteady for the good of the mushrooms; besides, a second shelf is inconvenient enough, and when it comes to a third or a fourth the inconvenience would be too great, and overreach any advantage hoped for in economy of space. An unheated mushroom house must be regarded as a shed, and treated similarly, as described in the following chapter.
In large, well appointed, private gardens, a mushroom house is considered an almost indispensable adjunct to the glasshouse establishment, and is generally built against the north-facing wall of a greenhouse. In this way it gets the benefit of the warm wall, and may be easily heated by introducing one or two hot-water pipes from the greenhouse system; besides, in winter the house may be entered from the glass house or adjacent shed, and in this way be exempted from the inclement breath of the frosty air that would be admitted in opening the outside door.
Fig. 10. Interior View of Mr. S. Henshaw's Mushroom House.
Mr. Samuel Henshaw's Mushroom House.—Mr. Henshaw has raised mushrooms several years at his place on Staten Island. His mushroom house is nine feet wide and sixty feet long. One side is a brick wall and the other is double boarded. The roof is of tin, in which there are three sashes each two by five feet, supplying ample light. At each end is a door giving convenient access to the interior, for carrying in and removing material without disturbing the bearing beds. In winter the roof is covered with a coating of salt hay, to preserve an equable temperature and prevent the moisture from condensing on the ceiling and falling in drops on the beds. The floor is of earth, which, when well drained, he thinks preferable to either brick or lumber. The floor is entirely covered with beds, no shelves or walks being used. This makes it necessary to step on the beds, but as no covering is employed it is always easy to avoid stepping on the clusters of young mushrooms, and so long as they are left uninjured the bed is seldom, if ever, impaired by the compacting effect of the treading. In order to maintain a necessary winter temperature of 60° a four-inch hot-water pipe extends the whole length of the house about two feet from the floor. On the other side of the brick wall is a greenhouse which, by keeping the wall warm, helps to keep the mushroom house warm. Mr. Henshaw divides this house into three equal beds. The part at the further end of the house is made up in the fall and comes into bearing in December; the middle part a month later to come in a month later, and the near end still a month later, to follow as another succession. Then, if need be, and he wishes to renew the bed at the further end of the house, he clears it out and supplies fresh material for the new bed.