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 ?-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.

Watering.

As the materials of mushroom-beds are generally moist, and as but little evaporation can take place in the structures in which they are usually grown, water is rarely necessary, and should not be applied until the surface of bed and soil are really dry. It should then be given copiously, enough to well moisten the bed, and it should be soft water heated to a temperature of 80 degrees given with a fine rose, and steadily and patiently applied equably over the whole surface of the bed. Waterings that merely wet the surface and saturate the crevices or lower parts of the bed are of no use. If one drenching is not sufficient to moisten the bed properly, another should be given. The flat form of bed is of course much more easily watered, and is on the whole the best for beds under cover. The position of beds will have a great influence on the quantity of water they require, so that it is almost impossible to give precise directions on this head; but I can scarcely conceive a case in which it will be necessary before six or eight weeks after the formation of a bed, and I have seen fine crops gathered without a single watering having been given. In watering old beds one ounce of guano to the gallon of water will prove beneficial.

Vermin in Mushroom Beds.

Woodlice are the greatest pests the mushroom-grower has to dispose of, and the most effective way of getting rid of them is by destroying them with boiling water. The surface of the bed being firm and covered with smooth firm soil, the only likely place to afford these creatures the interstices they usually retire into when disturbed, or when not employed in eating the head of every little mushroom that presents itself, is round the edges of the bed, and in the slit which often occurs between the bed and wall or sides of the shelves that support it. There they are likely to be found in great numbers, and may be destroyed wholesale by pouring boiling water all along the crack. If the beds be covered with hay or litter, it will be necessary to remove this and allow them time to retreat into their hiding places; and if the beds are made in any position that permits of the woodlice hiding in other places than the interstices round them, these places should be sought out, marked, and receive a searching dose of the scalding water all at the same time. It need hardly be added that, as it is not mushrooms, but creatures that rival ourselves in their love of mushrooms, that we wish to annihilate, the scalding water must not in any case be applied to the surface of the bed. If on the surface of old or dry beds, or those from which a good many mushrooms have been cut or pulled, there are any loose hollows or crevices in which the woodlice can take shelter, they should be sought out, cleared of vermin, levelled up, and made firm, so that the enemy cannot take up a position in which we cannot attack him. Should this plan fail, half an ounce of sugar of lead, mixed with a handful of oatmeal and laid in their tracks, will quickly destroy the pests.

The small mite is most destructive in a high temperature, and in summer, Mr. Cuthill says, “the maggot” will not breed in a house where the temperature does not exceed sixty degrees, and it is in hot, dry, and half-neglected houses that this pest is usually seen in summer. At that season there is little need to grow mushrooms indoors, and how they may be produced otherwise in great abundance is explained further on. The entrance of rats should also be guarded against.

Mushroom-beds come into bearing about six weeks from the time of spawning, and remain in bearing from two to five months, according to the position in which they are made, and the attention paid to them.

Treatment of Old Beds.

Upon the continuous bearing qualities of a mushroom bed a word may be said. It may savour of the ridiculous to say that a plant growing upon a dung bed may fail from the want of manure. Yet such is literally and positively the fact. Beds become worn out, the produce small and spindly, and we directly do away with them and make fresh ones. Instead of doing this, give the bed a thorough soaking of stable urine and water, at the temperature of 80 degrees, using the urine in the proportion of one part to five of soft water, and adding a wineglassful of salt to each canful; then coat the bed with fresh sod, cover it down with mats so as to promote the heating, and a second crop as good as the first may be obtained. In this matter I speak from experience, and Mr. Ingram, at Belvoir, has followed the same plan for many years with the most satisfactory result.

Gathering the Crop.

Gatherings should frequently take place, especially where the culture is pursued on a large scale. Where there are several beds in bearing, the mushrooms should be gathered every morning. In all cases they should be pulled or twisted out, never cut out, so as to leave decaying stumps in the beds. The holes made by pulling out the mushrooms should be filled with a little fine loam, of which a small heap may be kept in the house for this purpose.

Cleansing the House.

A word as to the necessity of a thorough annual cleansing of the mushroom-house. The fact that the French cave-cultivators find it necessary to shift from cave to cave, and find that after a cave has been in use a certain time, mushrooms cease to be produced in it, should act as a caution in this respect. In summer, when there is no need to attempt the culture indoors, the house should be thoroughly cleaned out, lime-whited, every surface scraped and washed, and the house freely opened, so as to thoroughly sweeten it.