Mushroom Culture: Its Extension and Improvement

by W. Robinson

Heat and Protection.

The temperature of the material of the beds should never, at spawning time, exceed 80 degrees Fahr.—about 70 is the most suitable regular temperature; and that of the mushroom-house should range between 50 and 60 degrees—not lower than 50. Assuming the materials to have been turned once after having heated, and again disturbed previous to being made into beds, they ought to be in a condition for spawning from ten to twelve days after being put together. It need hardly be said that this regularity of temperature can only be secured in properly-formed mushroom-houses. Where mushrooms are grown in these, with double ceilings and close-fitting shutters and doors, almost impervious to external influences, and where fresh beds are made from time to time, little or no artificial heat from pipes is required, though it is as well to have some at command in the case of unusually severe weather, or a break in the succession of beds, which would cause a deficiency of heat from fermenting materials. A covering of hay or dry litter is necessary for beds formed in the open air, and also for beds made in cool, half-open sheds; but not for those in regularly heated mushroom-houses or caves, in which there is a still, steady temperature. It should be about a foot thick, and should be immediately removed when it becomes wet or mouldy. This covering should be applied whenever the temperature of the bed begins to fall. It should not be used in any case where the temperature will permit of dispensing with it, as it is troublesome, and sometimes encourages insects. The heat of a bed may be reduced by opening holes six or eight inches deep with a thick pointed dibber, here and there, but it is only in exceptional cases that this is advisable, and it is desirable to husband all the ammonia and heat of the bed. The earthing over and firming of a bed has a tendency to subdue the heat in it. Where large sloping beds, say three feet deep at back, are made against the wall, I have seen Λ-shaped crates put beneath them at six feet apart, so as to permit of heating them by fresh supplies of manure. It is, however, a plan possessing little claim to general use. It is best not to depend on the hand, as is commonly done, for ascertaining the heat of the beds. Thermometers fixed on sticks of convenient size, to thrust in the beds, are sold, and remove all excuse for vagueness in this matter. Coverings of litter are sometimes useful in “drawing-up the heat” in a bed that has become somewhat chilled.

Spawning.

This is the phase of the culture which requires most attention, as to get the spawn to run regularly through the bed is to be nearly certain of securing a good crop. In this respect there do not seem to be so many differences of opinion among mushroom growers. Some, indeed, spawn immediately after the bed is made up; but, except where the materials are such as will not heat to more than 80 degrees, this is uncertain, or in other words bad, practice.

The important thing should be to ascertain if the spawn spreads through the bed properly. The usual practice is to earth up the bed immediately or very soon after it is spawned, and not a few take no further notice of the bed or beds till the time arrives when the mushrooms ought to appear. A better plan is not to finally earth the bed until the spawn is seen beginning to spread its white filaments through the mass; and should it fail to begin to do this in eight or ten days after spawning—the conditions being favourable—it is then better to insert fresh spawn or to re-make the bed, adding fresh materials if it be found to fail from being too cold. If people generally were to see whether the spawn had “taken” freely, instead of waiting for many weeks, not knowing whether it had or not, there would be fewer disappointments in mushroom culture.

The ordinary spawn bricks should be broken into pieces, say from about the size of walnuts to that of eggs; they do not break up into regular portions. Spawn in the more natural form in which we take it from the old beds, and in which it is used by the French, is ready to be inserted into the bed without any further manipulation. I believe this kind of spawn spreads more rapidly through the beds than our own brick spawn, and is, on the whole, much more desirable. As it is usually very dry it is a good plan to place some of it in the mushroom-house a few days before spawning, so that it may begin to absorb moisture. A dark place in a warm house, or gentle hotbed, would do as well, but in no case should it be done more than three days before spawning time. At spawning this might with advantage be mixed with some that has not gone through this process. A bushel of the ordinary brick spawn will suffice to spawn about one hundred square feet. All spawn should be inserted near the surface, just buried in the materials of which the bed is made. The thin flakes of spawn which the French use, and which are usually nearly the length and breadth of the open hand, are generally inserted into the bed edgeways, or in a direction slanting upwards, so that while one edge of the piece is buried three or four inches in the bed, the other is seen peeping through at the surface. Thus each flake of spawn is exposed to a slight difference of temperature, and, being thin and spongy enough to be immediately impregnated with the moist warmth of the beds, takes quickly and well. As to any particular mode of inserting the spawn, little need be said; if the bed be beaten so hard as many recommend, and which I do not believe to be at all necessary, a dibber will be required to insert the spawn; if not, it may be readily inserted with a trowel or with the hand. It is a good plan to use a mixture of two kinds of spawn.

Soil.

As regards the kind of soil used in earthing, it is not of nearly so much importance as is generally supposed; almost any soil will do; but those having heaps of good maiden loam laid by for gardening purposes will prefer to use a coating of that. I believe that any ordinary garden soil would do, and feel certain that it is a mistake to bestow the least trouble on procuring any particular kind of soil from a distance. The beds in the caves around Paris are covered over with a white putty-like substance, which would be sufficient to shake the nerves of any British mushroom-grower accustomed to his coatings of mellow loam. It is simply the fine rubbish from the stone breakage moistened, and smoothly and firmly pressed over the beds. We, if shown this on a bed that had failed, would assuredly attribute it to the “stuff” with which the bed was covered, though finer crops than these little beds yield it would be impossible to find. I notice this subject so that failures may be traced to their true causes, and not attributed to matters which really have but slight influence. The final covering of from one to two inches of loam or other soil should not be applied till the spawn has begun to spread through the bed, but a very thin layer of dryish loam may be placed on with advantage just after spawning has taken place, as it will serve to make the surface of a more equable temperature. It is a mistake to suppose that a deep covering is of any advantage. The final earthing should be of soil sufficiently moist or moistened to permit of its being pressed into a firm surface. However, unless it is exceptionally dry, a mere sprinkling of water will suffice.