Before we deal with the various ways of growing the mushroom, we will speak of the preparation of the material. As stable manure not only furnishes the nutriment, but forms the very soil in which mushrooms are produced artificially, and also supplies the heat which enables us to grow them to perfection at all seasons, by far the most important point connected with their culture is the management of this. It is very simple, but frequently, even by excellent gardeners, considered to require much more trouble and nicety than is really necessary. For example, it is quite common in good gardens to see the droppings collected carefully in some shed, or in the mushroom-house, and turned over almost as tenderly and carefully as the contents of the fruit-room. Good mushrooms are well worth this trouble; but, as it is quite unnecessary, it should not be done except in special cases.

To show the diversity of opinion among excellent mushroom-growers as to the preparation of the manure, I will quote a few of our most trustworthy authorities on the subject. Mr. W. Early, in “How to Grow Mushrooms,” lays great stress on the importance of gathering the droppings in a dry state. “Every advantage should be taken of opportunities of securing and placing them in any open shed, or other similar position, where they can be effectually sheltered from rains. In such a place, whilst the process of collecting is going on, every portion should be spread loosely over the floor, in moderate sized ridges, or in any other manner that will allow the air to get amongst it to assist in drying. It should also be tossed over or turned, and lightened up daily for the same purpose, until a sufficiency is gathered together for immediate use.”

This may be taken as a sample of the practice very extensively followed in this country. Happily, we have excellent mushroom growers who succeed without all this trouble, as the following remarks of Mr. J. Barnes will show:—“For the last thirty years I have made my beds entirely on the floor in sheds, wheeling in the stable dung as it is brought fresh from the stable, adding a fourth, or a little more than a fourth, of good friable loam, mixing both well together, pressing firmly down, and letting it remain about a week or so untouched. At the end of that time we turn it over, and if we consider it in too strong a state of fermentation we add a little more soil, and then tread down firmly. Very soon the bed is ready to be spawned, and encased in a couple of inches of soil; and in this way we get the finest crops of mushrooms, the beds remaining a long time in bearing. After the beds have been some time, say from six to twelve weeks, in bearing, and begin to get dry, and cease to bear well, we water them thoroughly with very clear liquid manure, made from sheep or deer or cow manure, which seems to start them again into bearing, and then we manage to keep some of the beds in bearing for many months at a time.” In the Field, Dec. 22, 1868, I stated that the manure for the mushroom-beds in the Royal Gardens, Frogmore, was not prepared in any elaborate way, but simply taken from a great heap fermenting in the yard, any parts of it that had become white from heat being moistened with water, and the whole being mixed with about a fourth part of loam. Mr. Cuthill, an authority on mushroom culture, tells us how the London market gardeners manage with their manure. As the material is brought home from the London stables, the short part is taken out of it, and the long litter is kept for the purpose of covering, as well as for forming the interior of ridges; for all mushroom-beds out of doors are made into ridges. The manure is not allowed to heat before it is put into the beds, if that can be prevented; for previously heated material does not produce such fine mushrooms. The fresher the horse-dung is, the longer the crop will last and every gardener who makes up beds with unheated droppings knows how superior they are to fermented manure.

In his own practice Mr. C. depended a good deal on heavy tramping to “keep down fermentation” when droppings were used in a fresh state. The French, who are great mushroom growers, allow the manure to heat first, but treat it very simply. They prepare it in the open air, first removing any pieces of wood or other extraneous matter that may have been mixed with it, and then place it long and short in beds two feet thick, or a little more, pressing it with the fork. When this is done, the mass or bed is well stamped, then thoroughly watered, and finally again pressed down by stamping. It is left in this state for eight or ten days, by which time it has begun to ferment, after which the bed ought to be well turned over and re-made on the same place, care being taken to place the manure that was near the sides at first towards the centre in the turning and re-making. The mass is now left for another ten days or so, at the end of which time the manure is about in proper condition for making the beds, either in the open air or in the caves. Sometimes it receives three turnings over, especially when the manure is long, and it occupies altogether about six weeks in preparation. As the wide heaps are turned over by the men, a water-cart remains alongside, and any portions of the mass that are dry and white from heat are moistened with water from a rose watering pot. This preparation shortens and mollifies the longer material considerably, mixes the mass well, and it is transferred to the caves in a slightly decomposed, well mixed, and moist, but not wet, condition. The French do not actually hammer or desperately tramp down the beds, as nearly all our writers on mushroom culture recommend, but press it pretty firmly; and I have seen as good crops on their light spongy beds as ever I have on those so firmly tramped down. I might give other striking instances of the diversity of opinion on this subject, but it is needless to multiply them.

My conclusions respecting the preparation of the manure for mushrooms are as follows:—1. That very careful preparation and frequent turning over of the manure undercover are not necessary to success, and that it is quite needless to prepare the manure under cover, except when it is gathered in a very small quantity, so that a heavy rain or snow would saturate it. Where, however, the culture is pursued on a very small scale, and, it may be, only one bed made, it is best to keep it in a covered shed. 2. That carefully picked droppings are not essential, though they may be more convenient. Excellent crops are gathered from beds made with ordinary stable manure, droppings and long materials mixed as they come; but when the manure is used as it comes from the stable, it should be allowed to ferment before being used. 3. That the best way of preparing manure for the general culture of mushrooms indoors, is to gather it in some firm spot, and allow it to lose its fierce heat. As it is usually gathered in an irregular way, precise directions as to turning over cannot well be given; but I am convinced that one turning will suffice when it has arrived at a strong heat, and then it should be thrown together for a week or so, when, in being disturbed and removed to make the bed or beds, its strong heat will be sufficiently subdued. Where large quantities of stable manure are in a fermenting state, there should be little difficulty in selecting material to form a bed at any time. Should it have spent its heat overmuch, it would be easy to revive it with some fresh droppings. 4. That stable manure may be used when fresh, but it should be always mixed with more than a fourth of good loamy soil. If this be kept under cover, or stacked so that it may be had in a rather dry condition, so much the better, especially if the fresh manure, &c., should be over moist. Beds thus made are most suited for cool sheds and the open gardens. 5. That a portion, say nearly one-fifth to one-third, of good and rather dry loam may always be advantageously mixed with the stable manure; the fresher the materials, the more loam should be used. In all cases it helps to solidify the bed, and it is probable that the addition of the loam adds to the fertility and duration of the bed. 6. That a thickness of from one foot to fifteen inches for the beds in an artificially heated house is quite sufficient. Eighteen inches will not be too much for beds made in sheds, though I have seen excellent crops on beds only a foot thick, in common sheds with leaky sides. All beds made indoors should be flat and firmly beaten down, though the absence of firmness is not, as some think, sufficient to account for want of success.

I will now quote a few words from Mr. Ayres on other materials for forming mushroom-beds than stable manure. He has given this, like almost every important subject in the range of horticulture, some attention. First among these may be mentioned sawdust which has been used for bedding horses or for riding-school tracks. Such a substance, thoroughly impregnated with urine and mixed with horse-droppings, forms an excellent material for mushroom-beds, especially if mixed with one-fourth of good fibrous loam. Such materials mixed and fermented together, and thrown into a bed a foot or eighteen inches in thickness, according to the temperature of the shed in which the bed is made, will be found to form capital material for growing this esculent, especially as it retains the heat for a long time. The worst of it is that the material is almost valueless after it has served the first purpose; and used as dung upon light land is rather injurious than otherwise. Then you may use leaves and loam, in the proportion of one part of the latter, in a turfy state, to four or five of fermenting leaves. These may be recently gathered from the trees, and should be allowed to attain a brisk heat before the loam is added, and then, after sweating for a week or ten days, may be turned, mixing the materials intimately together, and then the mass may be formed into a bed. A mushroom-bed of this kind should not be less than fifteen inches in thickness when thoroughly consolidated; and when so managed it will grow mushrooms just as well as dung. The sweepings of our streets and cattle markets, especially those parts that are paved and much frequented by horses—as, for example, cabstands, &c.—if collected when dry, and fermented a little, yield capital material for beds. Here from the cattle market we have the dung of horses, sheep, and cows mixed together in a finely divided state, the heating of which is gentle and regular. Material of this kind procured on dry days, thrown together to ferment once or twice, and then made into well-consolidated beds, will produce mushrooms of the finest quality, and continue in bearing a very long time. It is of the first importance that this material be collected in a dry state, as of course the slush of the streets would not do at all. Equal proportions of street sweepings and fresh leaves, properly fermented and mixed with loam, would perhaps make as good material for growing mushrooms as need be obtained. Of course the sweepings from those parts of the town most frequented by horses will be the best for the purpose I am writing about.

The idea of mushrooms ceasing to be prolific from the exhaustion of the active manure in the bed, I have mooted before. Lately several experiments have been tried which convince me that by taking three portions of recently-gathered leaves to one of turfy loam, and working them well together until the mass attains the desired temperature, sprinkling it, as the work of turning proceeds, with liquid direct from the stables, and forming this into a bed treated in the usual manner, it will give just as good mushrooms as the best horse manure in the world. It is the ammonia that is wanted for this crop, with a gentle heat. Secure these two things, and, with ordinary care, success is certain.

Before making the beds, while the material is in preparation, all particles of old wood, twigs, &c., that are found in the manure should be removed, as indeed should any extraneous matters likely to prove offensive or useless.

The best time for making mushroom-beds, where they are not regularly made in succession throughout the autumn and winter months, as they ought to be where there is abundance of material and a good mushroom-house, is in August and September, as in the early autumn months the natural heat is sufficient to cause the spawn to germinate freely, and beds made then ought to bear freely before and up to Christmas, and during autumn.

When making the bed, the chief object to bear in mind is the equal placing of the material. It should be well mixed and regularly and firmly placed so that the whole may be of a similar texture. Some heavily tramp and pound their beds to secure firmness; moderately done this is beneficial; thoroughly equable pressure with the fork, when the fork can be used, will with the pressure of firm earthing be sufficient; when beds are made on elevated benches in boxes, and in all positions where but a slight body of material is used, and where firmness cannot result from the general pressure of the mass, some kind of pressure with a wooden mallet or the like must be employed.

The beds once made, we next arrive at the spawning, and will first inquire, What is spawn?