This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
It must be equally and firmly beat down, that it may produce a mild, equable heat. Push a few stakes at intervals all round; drawing these out occasionally and feeling them with the hand, will afford a tolerable estimate of the interior warmth. The heat should never exceed ninety degrees after the bed is put up. If likely to get warmer than this, make holes all over it with a stout stake, and when the heat subsides to between seventy and eighty degrees, it is ready for planting the spawn. Beat the bed evenly all round, and insert the spawn just below the surface, in pieces the size of a hen's egg, twelve inches apart. Then case it over with a layer of strong loamy soil two inches in thickness, beating it firmly and left quite smooth. To prevent accident from over heating, it should only be partly soiled at first - say half way up - covering the whole some days afterwards. To prevent the soil from cracking in dry weather, a thin covering of short | straw or hay may be thrown over it; very little watering will be necessary. When it is found requisite to moisten the surface, let water pass through a fine rose on the outside of the covering, which is preferable to applying it directly on the bed.
Should it be made up about the middle of August, mushrooms may be expected towards the end of September, from six weeks to two months after spawning. When the nights become cold the covering should be increased, and to guard against damp, choose a clear day occasionally, turn off the covering, remove all decaying matter, and when all is dry, cover as before. It will keep in bearing for two months or more, if the interior heat is preserved by additional covering.
Various schemes may be resorted to for obtaining mushrooms in winter. Those who have a green-house may make a bed in the furnace room, if there is convenience, taking advantage of the heat that escapes from the furnace. A good supply may be had from a bed formed underneath the plant stage, provided the drippings of water from the pots above be guarded against by boards or water proof cloth. Portable boxes three or four feet long, two feet wide, and one in depth, filled with horse droppings and spawned in autumn, set in a dry place, will, when soiled over in rotation, and placed in the warm end of a green-house, afford a moderate supply. Even good sized flower pots may be thus prepared, and a few introduced at intervals. The equal temperature of an underground cellar, or root-room, is very suitable for the growth of this esculent; in such a place they may be had the whole year from successional beds, without much trouble or expense. The best crop I ever saw was in beds on each side of a close shed, with a row of fermenting manure between them. The frequent turning over of the manure filled the place with an agreeable moisture, and obviated the necessity of watering. The ammonia disengaged by decidedly beneficial.
Shelves, four feet wide and one in depth, risbuilt with timber, would not be expensive. Allowing three and a half feet on each Bide for beds, there would be three feet in the center for a path, underneath which a flue or hot water pipes should be placed. By having a bed on the surface, there would be space for two tier of shelves on each side, affording in all upwards of six hundred square feet of surface for growing the crop. This would be sufficient for a constant supply the whole year. Means should be provided in the roof for light and ventilation; four windows, three feet square each, would be sufficient for this purpose.
The principal material for forming beds in winter, or at any season, on shelves, should consist of horse droppings, with a little short litter intermixed. As this is collected, spread it out thinly to dry, turning it over frequently to prevent violent heating. The object is to get it into a dry state without decomposition. When it is in this latter condition, commence making the bed by throwing in the manure to the depth of three or four inches, and beat it firmly with the back of a spade, or, what is more expeditious, a flat heavy board, having two handles to work it with. Proceed in this manner until there is a depth often inches or so, firmly beaten, then insert the spawn just below the surface, as before. Insert the bulb of a thermometer into the bed, and should the heat rise above eighty degrees, bore holes eight or nine inches apart all over it. When the temperature is about seventy-five degrees, cover the surface with two inches of strong turfy loam, well beaten, leaving the surface smooth and level. The atmospheric temperature may range from fifty to sixty degrees with proportionate humidity. A sprinkling of short hay laid over the bed will keep it moist.
When it is found necessary to moisten the surface, apply it on the hay, which is preferable to watering directly on the surface of the soil; pass it through a syringe or fine rosed watering pot, observing to use the water a few degrees warmer than the temperature of the house; better to give it frequently than too much at a time. If duly attended to, mushrooms will be gathered in six or seven weeks, and keep in bearing for two or three months. An occasional watering with weak, clear manure water, will prolong their duration. In gathering the crop, the mushrooms should be twisted up as far as possible without disturbing the young ones around. When cut over, the remaining part of the stem is liable to hurt the others from its decomposition.