Manure.—In the management of the manure two essentials must be borne in mind. Not only is nourishment for the plant required, but warmth also. Probably a large proportion of the failures to grow Mushrooms might, if all the facts were known, be traced to some defect in the manure employed, or to some fault in its preparation. It must be rich in the properties which encourage and support the development of Mushrooms, absolutely free from the least objectionable odour, for the plant is most fastidious in its demand for sweetness, although it can dispense with light; and there must remain in the manure when made into a bed a sufficient reserve of fermentation to insure prolonged heat, no matter what the temperature of the atmosphere may be. Of course, the duration of the heat will depend very much on the care with which it is conserved by suitable covering and management. These requirements, formidable as they may seem, can be insured with extreme ease; indeed, the work is apparently far more difficult and complicated on paper than it proves to be in practice.
Preparation of the Bed.—The manure should come from stables occupied by horses in good health, fed exclusively on hard food. The most suitable store is the floor of a dry shed, or under some protection which will prevent the loss of vital forces. Ammonia, for example, is readily dissipated in the atmosphere or washed away by rain. The manure should neither be allowed to become dust dry, nor to waste its power in premature fermentation. Operations may be commenced with three or four loads. A smaller quantity increases the difficulty of maintaining the requisite temperature when fermentation begins to flag. The first procedure is to make the manure into a high oblong heap well trodden down. If the stuff be somewhat dry, a sprinkling of water over every layer will be necessary. In a few days fermentation will make the heap hot all through, and then it must be taken to pieces and remade, putting all the outside portions into the interior, with the object of insuring equal fermentation of the entire bulk. This process will have to be repeated several times at intervals of three or four days until the manure has not only been fermented but sweetened. When ready it will be of a dark colour, soft, damp enough to be cohesive under pressure, but not sufficiently damp to part with any of its moisture, and almost odourless; at all events the odour will not be objectionable, but may be suggestive of Mushrooms. Make a long bed, having a base about four feet wide, and sides sloping to a ridge like the roof of a house, with this difference—the narrow part of the ridge is useless, and the top should, therefore, be rounded off when about a foot across. Some growers prefer a circular bed of six or eight feet diameter at the bottom and tapering towards a point, after the shape of a military tent; but here again the point will be worthless, and the bed may terminate abruptly. Either the long bed or the round heap answers admirably. Tread the manure down compactly, and for the sake of appearances endeavour to finish it off in a workmanlike manner. During the first few days there will be a considerable rise in the temperature, which will gradually subside, and when the plunging thermometer shows that it has settled down to a comfortable condition of about 80° the bed must be spawned. Experienced men can determine by the sense of touch when the temperature is right, but the inexperienced should rely entirely on the thermometer. The question will arise as to the period of the year when operations should be commenced. Well, the experts who grow Mushrooms in the open ground for market gather crops almost the year round; but a beginner will do wisely to start under the most favourable natural conditions, and these will be found about midsummer, because the bed will commence bearing before winter creates difficulty as to temperature.
Spawning and After-management.—Break each cake of spawn into eight or ten pieces, and force every piece gently a little way into the manure at regular intervals of six to nine inches all over the bed, closing the manure over and round each piece of spawn. The practice of inserting spawn by means of the dibber is to be strongly condemned, for it leaves smooth, hollow spaces which arrest the mycelium; and very small pieces of spawn should be avoided because they generally result in small Mushrooms. Immediately the spawning is completed, a thick and even covering of clean straw or litter of some kind should be laid over the bed, secured from wind by canvas, mats, hurdles, or in some other way. From good spawn the films of mycelium will begin to extend within a week. In the contrary case an examination of the pieces will show that they have become darker than when put into the bed, which means that they have perished. Then the question will arise as to whether the bed or the spawn is at fault, and the former must either be spawned again or broken up. Supposing the spawn to show signs of vitality, the time has come for covering the bed with a layer of rather moist soil, pressed lightly but firmly on to the manure with the spade or fork, so that the earth will not slip down. At once restore the covering of litter, &c., and wait patiently for about seven or eight weeks for the crop. Meanwhile the plunging thermometer ought to be consulted daily. Until the Mushrooms appear the instrument should not indicate less than 60°, and while in bearing not less than 55°. Experience proves that the most violent alternations of temperature may be combated by regulating the thickness of the covering. Although it may possibly be necessary to resort to eighteen inches of litter or more during hard frost or the prevalence of a cutting east wind, a much thinner covering will suffice in milder weather.
Should the temperature of the bed, through inexperience in the management of it, sink below the point at which Mushrooms can grow, we advise the exercise of a little patience. We have known several instances of beds made in autumn producing no crop at the expected time, but which have borne fairly in the following spring or summer. But in the event of the first effort failing outright there is no great loss. The manure, which is the most costly item, will still be available for the garden, and an observant man will pretty well understand in what respect he must amend his course of procedure.
Water.—Moisture is of great consequence, for a dry Mushroom bed will soon be barren also; but whenever water is given it must be applied tepid and from a fine rose. To slop cold water over a Mushroom bed is about as reasonable a procedure as putting ice into hot soup. Water is best administered in the afternoon of a genial day, and should be sufficient to saturate the bed. Immediately it is done the covering of litter and canvas must be promptly restored to prevent the temperature from being seriously lowered by rapid evaporation. A couple of stakes driven from the crown to the bottom of the bed at the time of making up the heap are useful as indicators of moisture, and may occasionally be drawn out and examined.
In gathering the crop, only a small portion of the bed should be uncovered at a time. This should be the rule at all seasons, and the strict observance of it will prevent a mistake in cold weather, for then, if the bed is carelessly uncovered and much chilled, the crop will come to an end, when perhaps it would, if properly handled, be at high tide and full of profit. Another rule should be enforced, to this effect, that every Mushroom must be taken out complete, and if the root does not come with the stem, it must be dug out with a knife. Any trifling with this rule will prove a costly mistake. The stem of a Mushroom, if left in the ground, will produce nothing at all. But it may attract flies, and it certainly will interfere with the movements of the mycelium at that particular spot, and actually prevent the production of any more Mushrooms. The old practitioners were accustomed to leave the stem in the ground, and they were content with about one-third of the crop now produced on beds that are, perhaps, not better made than were theirs. But they had a notion about the powers of the root which increased knowledge of the subject has shown to be fallacious.
In Pastures.—As already indicated, Mushrooms are often to be found in abundance in well-stocked pastures during the late summer months, and where favourable conditions exist it is an excellent plan to insert pieces of spawn two inches deep in the turf in June and July.
Turf Pits.—The facility with which Mushrooms may be raised under simple methods is illustrated by the practice of growing them inside the turf walls of cool pits. In the country turf walls are common, and they offer the advantage of growing Mushrooms in addition to the purpose they usually serve. After determining the size of the pit, and accurately marking it on the ground, cut the turf into narrow strips, say three or four inches wide, and of exactly eighteen inches length. The strips should be closely laid, grass side downwards, across the width of the walls—not longitudinally—except at the corners, where the layers should cross each other. The front and back walls to be rather above the required height, because the turf always scales down a little, and the two ends must gradually rise from front to back. The top layer may be right side up, when it will keep green for a long time. As the work proceeds insert lumps of spawn at intervals in every layer, about three or four inches from the inside edge. A wooden frame will be requisite on the top to carry the glass lights. This structure makes a useful cool pit and a Mushroom bed from which supplies may sometimes be gathered for years. In the summer it will be necessary to keep the walls moist by means of the syringe, or they will cease bearing.
Indoor Beds.—Mushrooms may be grown almost anywhere, evenly in a cellar, or on the wall of a warm stable, provided only that the mode of procedure is in a reasonable degree adapted to the requirements of the fungus. Ordinary pits and frames are also serviceable, and many gardeners obtain good crops in autumn by the simple process of inserting a few lumps of spawn in a Cucumber or Melon bed while the plants are still in bearing. Between spawning and cropping a period of six or eight weeks usually elapses, so that if the plan just mentioned be adopted, the spawn should be introduced in the height of summer, both to insure it a warm bed and to allow time for the crop to mature before the season runs out. Sheds and outhouses not only afford shelter and space for beds on the floor, but the walls can be fitted with shelves on which Mushrooms may be plentifully grown. In all cases the shelves should be two feet apart vertically, and each shelf should have a ledge nine inches deep. The walls of a house may be quickly and cheaply fitted with woodwork for the purpose, but brick is so much better than wood that whenever it is possible to employ brick it should have the preference. As regards the ledges, they should be of stout planking in any case, and should not be fixed, because of the necessity for clearing the shelves and renewing the soil periodically. The details of cultivation are the same within doors as without, but the roof gives valuable protection, and helps to maintain the beds at a suitable temperature.
A proper Mushroom-house for production during winter should be heated with hot water, and have an opaque roof. There is nothing so good for the crop as a roof of thatch, but there are many objections to it, and usually slate is employed. A double roof will pay for its extra cost by promoting an equable temperature. A few side lights fitted with shutters are necessary, as there should be a good light for working purposes; but the crop does not need light, and a more steady temperature can be maintained in a dark house than in one which has several windows. The most convenient dimensions for a Mushroom-house are: length, twenty-five feet; width, twelve feet; height at sides, six feet, to allow of a bed on the floor, and a shelf four feet above it; the ridge rising sufficiently for head room, and to shoot off water. There will be room for a central path of four feet, and a bed of four feet on each side. An earth or tile floor and a slate or stone shelf will, with one four-inch flow and return pipe, complete the arrangements. The less wood and the less concrete the better; there is nothing like porous red tiles for the floor and stone for the shelves, with loose planks on edge to keep up the soil, a few uprights being sufficient to hold them in their places.