Growing mushrooms in greenhouses.

Any one who has a greenhouse can grow mushrooms in it. And it does not matter what kind of greenhouse it is, whether a fruit house, a flower house, or a vegetable house, it is available for mushrooms. One of the advantages of raising mushrooms in a greenhouse is that they grow to perfection in parts of the greenhouse that are nearly worthless for other purposes; for instance, under the stages, where nothing else grows well, although rhubarb and asparagus might be forced there, and a little chicory and dandelion blanched.

Cool greenhouses, in all cases, are better for mushrooms than hothouses. Cool houses are seldom kept at a lower temperature than 45 deg. or 50 deg. in winter, while hothouses run from 60 deg. to 70 deg. at night, with a rise of ten to twenty degrees by day, and this is too hot for mushrooms. It is a very easy matter, by means of covering with hay or boxing over and covering the boxing with hay or matting, to keep a mushroom bed in a cool house warm and free from marked changes in temperature; but it is a difficult matter to keep a mushroom bed in a hothouse cool enough and prevent sudden rises in temperature.

On Greenhouse Benches.- It sometimes happens that the beds are formed on the greenhouse benches, and the mushrooms occupy the same place that might be assigned to roses or any other planted-out crop. The beds on the benches are made one board deep, that is, eight to ten inches of short, fresh manure, and otherwise as in the case of beds anywhere else. After the beds are spawned and cased with soil, by covering them over with a layer of straw litter or hay, sudden drying out of the surface is prevented, and in order to further prevent this drying it is a good plan to sprinkle some water over the mulching every day or two, but not enough to soak through into the bed. About the time the young mushrooms commence to show themselves, remove the mulching and replace it with a covering of shutters raised another boards height above the bed, or with strong calico or plant-protecting cloth hung curtain-fashion over the beds.

My principal objection to mushroom beds on greenhouse benches is their liability to frequent and marked changes of atmospheric temperature and moisture, and to drying out. In midwinter they may be all right, but as spring advances and the sun’s brightness and heat increase, the susceptibility of the beds to become dry also increases.

In Frames in the Greenhouses.- Mr. J. G. Gardner has a range of greenhouses some 900 feet long the longest unbroken string of glasshouses that I know of for the forcing of fruit and vegetables in winter; grapes, peaches, nectarines, figs, tomatoes, cucumbers, snap beans, peas, lettuce. This range is divided into several compartments, to accommodate the different varieties of crops, also so that some can be run as succession houses. In order to make the most of everything, market-gardener-like, he doubles up his crops wherever possible, and for this end he finds no crop more amenable and profitable than mushrooms. It matters nothing to him whether the house is cold or warm, he can grow mushrooms in it anyway, and in order to be master of the situation he makes his mushroom beds in hotbed frames inside the greenhouses. By attending to ventilating or keeping close, or covering up or leaving bare, he can properly regulate the temperature of the mushroom bed, no matter how hot or cold the atmosphere of the greenhouse may be. In the same way by shading the panes or unshading them he governs the light admitted to the mushrooms.

The greenhouses in which the mushrooms are grown are orchard houses, that is, glasshouses in which peach and nectarine trees are grown and forced. As these trees fruit and finish their growth early, it is necessary that they be kept as cool and inactive as possible in the fall and early winter, and started again into growth in late winter. In the fall, therefore, the fermenting material being confined in frames retains warmth enough for the proper development of the mushrooms, and as the winter advances and the heat in the frames begins to wane it becomes necessary to begin heating the greenhouses in order to start the trees into bloom and growth, and thus are provided very favorable conditions for the continued production of the mushroom crop.

The frames used are common hotbed box frames seven feet wide and carrying three and one-half feet wide sashes. A string of them is run along the middle of the greenhouses, for greenhouse after greenhouse is occupied by them. They are flat upon the floor, and in the early part of the season alone in the greenhouses. But as the winter advances a temporary staging is erected over these frames, on which spiraeas, peas, beans, or other flowers or vegetables are to be grown. These love the light and a position near the glass, whereas the mushrooms grow perfectly well in the dark quarters of the frames under the stages. If he did not grow mushrooms under these stages the room would be unoccupied, hence unproductive; but by occupying it with mushrooms he not only gets peaches and snap beans at once out of the same greenhouse, but also a crop of mushrooms, often worth as much as the other two.

In preparing the beds in the frames they were made up a foot deep, very firm, and with New York stable manure brought direct from the cars. There was no preliminary preparation of the manure. A layer of loam one and one-half inches deep was then spread over the surface and forked into the bed of manure one and one-half inches deep, so as to form an earthy mat three inches deep. This was then packed solid with the feet, and a two-inch layer of loose manure added all over. In about ten days the temperature three inches below the surface was about 95 deg., and the beds were then spawned. In spawning, drills were drawn across the beds about a foot apart and just deep enough to touch but not penetrate the earthy mat before referred to. The broken spawn was then sown in the drills and covered with a layer of loam one and one-half to two inches deep, which was tamped slightly. The sashes were then put on and tilted up a little to let the moisture escape. By the time the mushrooms appeared there was very little need of ventilating, as the condensation of moisture on the glass was scarcely apparent; but ventilation is easily guided by the appearance of moisture on the glass, the more of this the more ventilation should be given. To begin with, there was no attempt at shading the frames; but as soon as the mushrooms began to appear the beds were shaded, and mostly by the crops of other plants on the stages above them. These frame beds were made up last October, and began bearing in December, and on March 14 Mr. Gardner wrote me: “The mushrooms in my frames have done grandly. I cut large basketfuls to-day of the finest mushrooms I have ever seen, some of them measuring five inches in diameter before being fully expanded.”

And further, in submitting the above notes to him for verification, he adds: “There is one vital point we should impress upon all who grow mushrooms in frames or under greenhouse benches, namely, that sudden changes of temperature must be avoided. While light, in my opinion, is good for mushrooms, it causes a rise of temperature, and this we must guard against. In order to maintain a uniform temperature all glass exposed to light or heat in any other way should be covered with some non-conducting material. Rye straw is the best thing for this purpose that I know of. Indeed, neglect of this simple matter, in cases where sunlight and heat from hot-water pipes come in contact with the young mushrooms or mycelium on the surface of the beds, is the cause of many failures in growing in frames and greenhouses.”

Under Greenhouse Benches.- Open empty spaces under the stages anywhere are good places for mushroom beds. However, carefully observe a few points, to wit: A dry floor under the beds is imperative, for a wet floor soaks and chills the beds, and renders them unhealthy for the spawn; but the common earth floor is good enough, provided water does not stand upon it at any time; if it does, the floor to be under the beds can be rendered dry by raising it a little higher than the general level, or using a flooring of old boards. Beds should not be built close up against hot-water pipes, steam pipes, or smoke flues, as the heat from these when they are in working condition will bake the parts of the beds next to them and render them unproductive, and also crack and spoil the caps of the mushrooms that come up within a foot or two of the pipes. But this injury from hot pipes and flues can be lessened greatly by boxing the pipes, so as to shut off the heat from the mushroom beds and allowing it full escape upward; then the beds can be made, with safety, up to within a foot of the pipes. As a rule, hot-water pipes are run around under the front benches of a greenhouse, then it would not be advisable to make beds under those benches. The middle bench is the one most commonly free from pipes, hence the one best adapted for beds. It has more headroom, and therefore easier working facilities. Steam-heated greenhouses generally present the best accommodations for mushroom beds, because the pipes occupy less room under the benches than do those for hot water, and they are always kept higher from the ground.

Among Other Plants on Greenhouse Benches.- It sometimes happens that mushrooms spring up spontaneously among the roses, carnations, violets, mignonette, and other crops that are grown “planted out” on the benches, and this is particularly the case where fresh soil had just been used, in whole or part, for filling the bench beds. These mushrooms come from natural spawn contained in the loam or manure before they were brought indoors, and which is apt to be true virgin spawn. The mushrooms are generally of the common kind, grown from brick spawn, but occasionally a much larger and heavier sort is produced, and this is the “horse” mushroom. It is perfectly good to eat, only of coarser quality than the other.

A fair and certain crop can be obtained by planting pieces of spawn in the beds here and there between the plants and where they will be least likely to be soaked with water. In order to further insure the development of the spawn, holes about the size of a pint cup should be scooped out here and there over the bed, and filled up solidly with quite fresh but dry horse droppings, with the piece of spawn in the middle, and covered over on top with an inch of loam, so as to leave the whole surface of the bed level. So small a quantity of dry manure surrounded with cold earth will not heat perceptibly, and the moisture of the loam about it will soon moisten it, no matter how dry it may be. The dry, fresh droppings are the very best material for starting the mycelium into growth.

Growing Mushrooms in Rose Houses.- George Savage, the head gardener at Mr. Kimball’s greenhouses, Rochester, N. Y., grows mushrooms very successfully under the benches of the rose houses. When he makes up his earliest mushroom beds in the fall the rose house is kept cool, and this is an advantage to the mushroom beds, which get all the warmth they need from the fermenting manure; but as November advances, and the heat in the beds begins to wane the rose houses are “started,” and this artificial warmth comes in good season to benefit the growing mushrooms. The roses, in this case, are planted out on benches, hence there is scarcely any dripping of water from above upon the mushroom beds below.

Mr. George Grant, of Mamaroneck, N. Y., who grows mushrooms in the greenhouse, I called to see last January, and was very much pleased with his simple and successful method. The beds were then in fine bearing, very full, and the crop was of the best quality. The beds were made upon the earthen floor of his tomato-forcing house and under the back bench. The bed was flat, seven to eight inches deep, with a casing of a ten-inch-wide hemlock board set on edge at the back, and another of same size against the front. The bed was made of horse droppings, six inches deep, and molded over with fresh loam one and one-half inch deep. Over the whole, and resting on the edges of the hemlock boards, was a light covering of other boards, with a sprinkling of hay on top of them to arrest and shed drip, and maintain an equable temperature in the bed.

Mr. Abram Van Siclen, of Jamaica, Long Island, is one of the largest mushroom growers for market in the country, as well as one of the most extensive growers of market-garden truck under glass around New York. He devotes an immense area under his lettuce-house benches to the cultivation of mushrooms. The beds are made upon the floor in the usual way, only for convenience’ sake, to admit of plenty of room in making up the beds and gathering the crop, besides avoiding the necessity for building higher structures than the ordinary lettuce greenhouses, the mushroom beds are sunken about eighteen to twenty-four inches under the level of the pathways. As the lettuces are planted out upon the benches there is very little drip from them, hence the sunken beds are well enough. And the temperature of a lettuce house is about right for a long-lasting mushroom bed. Light is excluded by a simple covering of salt hay laid over the beds, and sometimes by light wooden shutters set up against the aperture between the lettuce benches and the floor, in this way boxing in the mushrooms in total darkness.

Mr. William Wilson, of Astoria, has an immense greenhouse establishment near New York. In his greenhouses, under both the side and middle benches, he grows mushrooms, and when I saw them in January there were about 300 square yards of beds. The beds were flat, about nine inches thick, built upon the ground, and protected from strong light by having muslin tacked over the openings between the benches and the beds alongside the pathways. But his crop was suffering from drip. Mr. Wilson told me he could not begin to supply the demand. He says whatever he makes on mushrooms is mostly clear gain. They occupy space that otherwise would remain unoccupied, and he needs the manure and the loam in his florist business, and it is in better condition for potting after it has been rotted in the mushroom beds than it was before it was used for this purpose.

Drip from the Benches.- This must be prevented from the beds above, else it will soak or chill, and in a large measure kill the spawn. I have seen many examples of this evil. The beds would be full of drip holes all over their surface, and although a good many mushrooms here and there about the bed might perfect themselves, multitudes only reach the pin-head condition or possibly the size of peas and then fogg off in patches. It is not one or two little mushrooms in a clump that fogg off, but where one foggs off all of the little ones in that patch go, for it is not a disease of the individual mushroom, but of the mycelium or mushroom plant that runs in the bed, and when this is injured or killed all the little mushrooms arising from this particular patch of plant are robbed of sustenance and must perish.

In greenhouses where the benches are occupied with roses, carnations, bouvardias, violets, or lettuces, “planted out,” as commercial florists and gardeners generally grow them, there is very little drip, because while the plants on these benches are freely watered, the soil is never soaked enough for the water to drain from it in dripping streamlets, as is continually the case in greenhouses where potted plants are grown on the stages. Under these “planted out” benches, if care is exercised, mushrooms can be grown in open beds; in fact, it is about the best place and condition for them in a greenhouse.

With stages occupied by plants in pots provision needs to be made to ward off the drip from the mushroom beds, by erecting over, and conveniently high above them, a light wooden framework, on which rest light wooden frames covered with oiled paper, oiled muslin, or plant-protecting cloth. In fact, three light wooden strips run over the bed, as shown in Fi, or three strings of stout cord or wire run in the same manner will answer for small beds, and act as a support for the oiled muslin or plant-protecting cloth. Building paper is sometimes used for the same purpose. Mr. J. G. Gardner uses ordinary hotbed frames and sashes, as described in a previous chapter. Light wooden shutters made of one-half inch or five-eighths inch pine may be used for the same end, and will last for many years.

The beds under the greenhouse benches may be made up in the same way as are beds anywhere else; that is, flat upon the floor and between two boards set on edge, as seen in Fi, or in ridges under the high or middle benches, as in Fi, or in banked beds against the back wall, as shown in Fi. Generally the flat bed is the most convenient to make and take care of.

In open, airy greenhouses it is always well to inclose the mushroom beds in box casings and with sash or shutter coverings, to prevent draughts and fluctuations of temperature and atmospheric moisture. This can easily be done by making the sides a board and a half (fifteen inches), or two boards (twenty inches) high, and covering over with light wooden shutters, sashes, or muslin or paper-covered light frames. See Fi.

Ammonia Arising.- Ammonia arising from the manure of the mushroom beds in the greenhouse may be injurious to the other inmates of the greenhouse. If the manure has been well prepared before it was introduced into the greenhouse, the ammonia arising from it will not, in the least degree, injure any other plants or flowers that may be in the house; but if the manure is fresh, hot, and rank, the opposite will be the case. Beds in greenhouses should always be made up of manure that has been well prepared beforehand out of doors or in a shed, and as it is brought into the greenhouse it should at once be built solidly into the beds. Then very little steam will arise from the beds; in fact, it will be imperceptible to sight or smell.