Read CHAPTER X of Mushrooms: how to grow them a practical treatise on mushroom culture for profit and pleasure , free online book, by William Falconer, on ReadCentral.com.

Mushroom spawn.

What is mushroom spawn? Is it a seed or a root? Do you plant it or sow it, or how do you prepare it? are some of the questions asked me now and again. To the general public there seems to be some great mystery surrounding this spawn question; in fact, it appears to be the chief enigma connected with mushroom-growing. Now, the truth is, there is no mystery at all about the matter. What practical mushroom growers call spawn, botanists term mycelium.

The spawn is the true mushroom plant and permeates the ground, manure, or other material in which it may be growing; and what we know as mushrooms is the fruit of the mushroom plant. The spawn is represented by a delicate white mold-like network of whitish threads which traverse the soil or manure. Under favorable circumstances it grows and spreads rapidly, and in due time produces fruit, or mushrooms as we call them. The mushrooms bear myriads of spores which are analogous to seeds, and these spores become diffused in the atmosphere and fall upon the ground. It is reasonable to suppose that they are the origin of the spawn which produces the natural mushrooms in the fields, also the spawn we find in manure heaps. But we never have been able to produce spawn artificially from spores, or in other words, mushrooms have never been grown by man, so far as I can find any authentic record, from “seed.” How, then, do we get the spawn? By propagation by division. We take the mushroom plant or spawn, as we call it, and break it up into pieces, and plant these pieces separately in a prepared bed of manure or other material, under conditions favorable for their growth, and we find that these pieces of spawn develop into vigorous plants that bear fruit (mushrooms) in about two months from planting time. When the spawn has borne its full crop of fruit it dies.

Well, then, if we can not produce spawn from spores, and the spawn in the beds that have borne mushrooms has died out, how are we to get the spawn for our future crops? is a question that may suggest itself to the inexperienced. By securing it when it is in its most vigorous condition, which is before it begins to show signs of forming mushrooms, and drying it, and keeping it dry till required for use. But in order to secure the spawn we need to take and keep with it the manure to which it adheres or in which it is spreading. In this way it can be kept in good condition for several years and without its vitality being perceptibly impaired. Keeping it dry merely suspends its growth; as soon as it is again submitted to favorable conditions of moisture and heat its pristine activity returns.

Mushroom spawn can be obtained at any seed store. Our seedsmen always keep it in stock, both the brick (English), and the flake (French) spawn. It is retailed in quantities of one pound or more, and as the article is perfectly dry it can be easily sent by mail in small quantities.

The seedsmen import it from Europe every year along with their seeds. A prominent Boston seedsman writes me: “We get our supply through the London wholesale seedsmen, for the sake of convenience and cheaper ocean freight, etc. Coming with a shipment of other goods and on same bill of lading brings the freight charges down. The low price at which mushroom spawn is sold in quantity can only be maintained with low freight rates, as there is a duty here of 20% on the article.”

By direct inquiry of the leading importers in different cities I find that we import about 4500 lbs of French or flake spawn, and 4000 bushels, or 64,000 lbs of English or brick spawn, and that fully a half of this whole importation is handled by the seedsmen of New York city. In New York one firm alone, who make a specialty of supplying market gardeners, has in one year imported 1500 bushels of brick spawn. But the vicinity of New York is the great mushroom-growing center of the country, also the best market for mushrooms in the country. One gardener at Jamaica, L. I., bought 1000 lbs of brick spawn at one time, and a neighbor of his bought 400 lbs; this shows what a large quantity of spawn market gardeners require. And the demand this year is unprecedented; some of our leading importers had sold out their supply before the first of November. And it is not private growers so much as market growers who are the cause of this; the market men find there is money in growing mushrooms and they are going into it.

Spawn comes in the form of dry, hard, solid manure bricks, and also in the form of flakes of half rotted strawy manure. These bricks and flakes are completely permeated with the mushroom mycelium.

The brick spawn is commonly known as English spawn, and what is imported into this country is made in England, mostly about London. The bricks made by the different manufacturers vary a little in size and weight; in some cases ten bricks go to the bushel, in others fourteen, and in others sixteen. This last is the commonest sized brick, and weighs exactly a pound, and measures about eight and one-half inches long, five and one-fourth inches wide, and one and one-fourth inches thick; it is what the London spawn makers call a 9x6x2 inch brick, but it shrinks in drying. In retailing brick spawn in this country it is sold by weight and not by measure.

Mill-track mushroom spawn is advertised by some of our seedsmen, but what they sell under this name is only the ordinary English brick spawn. One of our prominent seed firms who advertise it write me: “Genuine mill-track spawn used to be the best in England, but it has been superseded, although European gardeners still call for English spawn under the name of ‘mill-track.’” The real mill-track spawn is the natural spawn that has spread through the thoroughly amalgamated horse droppings in mill-tracks or the cleanings from mill-tracks. It is usually sold in large, irregular, somewhat soft lumps, and is much esteemed by spawn makers for impregnating their bricks, but nowadays, that horses have given place to steam as a motive power in mills, we have no further supply of mill-track spawn for use in spawning our mushroom beds. We do not feel this loss, however, as the spawn now manufactured by our best makers will produce as good a crop of mushrooms as the old mill-track natural spawn used to do.

The flake spawn is what is generally known as French spawn, and is imported into this country from France. But the manufacture of “French” spawn for sale, however, is not strictly confined to France. It is put up in two ways, namely, nicely packed in thin wooden boxes, each containing two or three pounds of spawn, and also loose in bulk when it is sold by weight or measure.

Virgin spawn is what we call natural spawn or wild spawn; that is, the spawn that occurs naturally in the fields, in manure piles, or elsewhere, and without any artificial aid. It is supposed to be produced directly from the mushroom spores, and is not a new growth of surviving parts of old spawn that may have lived over in the ground. It is far more vigorous than “made” spawn, and spawn makers always endeavor to get it to use in spawning the artificial spawn. It is seldom used for spawning mushroom beds because not easy to obtain. Now and again we come upon a lot of it in a manure pile; it looks like a netted mass of white strings traversing the manure. As soon as discovered secure all you can find, bring it indoors to a loft, shed, or room, and spread it out to dry; after drying it thoroughly keep it dry and preserve and use it as you would French spawn, for it is the best kind of flake spawn. In using virgin spawn for spawning beds I have obtained larger and heavier mushrooms than from “made” spawn, and the beds lasted longer in good bearing, but the weight of the whole crop has not been more than from artificial spawn.

How to Keep Spawn.- Spawn should be kept in a dry, airy place, somewhat dark, if convenient, and in a temperature between 35 deg. and 65 deg.. Wherever things will “must,” as in a cellar, cupboard against a wall, or in a close, damp building, is a very poor place for keeping spawn. If the spawn is perfectly dry and kept in a dry, airy place, and not in large bulk, and covered, it will bear a high temperature with apparent impunity, but whenever dampness, even of the atmosphere, is coupled with heat, the mycelium begins to grow, and this, in the storeroom, is ruinous to the spawn. Judging from our natural mushroom crops, the spawn for which must be alive in the ground in winter, one concludes that frost should not be injurious to the artificial spawn, still my experience is that hard frost destroys the vitality of both brick and flake spawn. And this is one reason why I get our full supply of spawn in the fall and keep it myself rather than submit it to the mercy of the seed store.

New Versus Old Spawn.- How long spawn may be kept without its vitality becoming impaired is an unsettled question, but there is no doubt, if properly kept, it will remain good for several years. But I can not impress too strongly upon the reader the importance of using fresh spawn. Do not use any old spawn at any price; do not accept it gratis and ruin your prospect of success by using it. It takes three months from the time when the manure is gathered for the beds until the mushrooms are harvested. Can you, therefore, afford to spend this time, and undergo the care and trouble and expense, and court a failure by using old spawn? We have risks enough with new spawn, let alone old spawn. I do not use any more old spawn, but I have used it often and long enough to be convinced of its general worthlessness, unless preserved with the greatest care.

How to Distinguish Good from Poor Spawn.- This is a very difficult matter, notwithstanding what people may say to the contrary. If we could positively tell good from bad spawn, we would never use bad spawn, and, therefore, with ordinary care, have very few failures in mushroom-growing; for good spawn is the root of success in this business. Spawn differs very much in its appearance; sometimes the bricks show very little appearance of the presence of spawn, and still are perfectly good; and again, we may get bricks that are pretty well interlaced and clouded with bluish white mold or fine threads, and this, too, is good. When the bricks are freely pervaded with pronounced white threads this is no sign that the spawn is bad. Bricks dried as hard as a board may be perfectly good; so, too, may be those that are comparatively soft. Mushroom spawn should have a decided smell of mushrooms, and whatever cobweb-like mold may be apparent should be of a fresh bluish white color, and the fine threads clear white. Prominent yellowish threads or veins are a sign that the mycelium had started to grow and been killed. Distinct white mold patches on the surface of the bricks indicate the presence of some other fungous parasite on the mushroom mycelium; the absence of any mushroom smell in the spawn indicates its worthlessness and that the mycelium is dead. One familiar with mushroom spawn can tell with considerable certainty “very living” spawn and “very dead” spawn, but I am far from convinced that any one can decide unhesitatingly in the case of middling or weak spawn.

Mr. S. Henshaw, in Henderson’s Handbook of Plants, tells us: “The quality of the spawn may be very easily detected by the mushroom-like smell, ... and I should have no hesitation in picking out good spawn in the dark.” Sanguine, surely, but I have tried it and found the test wanting. M. Lachaume says that good spawn shows “an abundance of bluish-white filaments well fitted together, and giving off a strongly marked odor of mushrooms. All those portions which show traces of white or yellow mold or have a floury appearance, should be rejected and destroyed.” Mr. Wright says: “A brick may be a mass of moldiness, and yet be quite worthless; and if the mold has a spotted appearance, as if fine white sand had been dredged on and through the mass, it is certain there is no mushroom-growing power there.... If thick threads pass through the mass and there are signs of miniature tubercles on them, then the spawn may be regarded as too far gone.... Clusters of white specks on the spawn denote sterility.”

Mr. A. D. Cowan, of New York, who has the reputation of being an excellent judge of mushroom spawn, writes me: “To correctly judge the quality of brick spawn by its appearance requires experience in handling it, and a trained eye which enables one quickly to detect good from bad, fair to middling. As two lots seldom come exactly or nearly alike in appearance, it is hardly possible to give precise rules to follow, excepting the never-failing requisite which the spawn must possess to be good, namely, the moldy appearance on the surface, the more the better, without showing threads. Too many of these to a given space are a sure indication of exhausted vitality, arising generally from the bricks being heaped together when in process of manufacture, before they are sufficiently dried. Healthy bricks are usually of a dusty brown color, and of light weight. Black colored spawn is to be avoided, as a rule, and when the black appearance is very prevalent in a cargo of bricks it is a strong indication that the spawn has not run its course; and as it is not expected to do so after it has reached the hands of the retailer it is economy to cast it aside. Some persons break a brick into several pieces to see how it looks inside. To the experienced eye this is not necessary, or even to lay hands upon it, as the outward moldy appearance is the best of all evidence of its healthy vitality, and this never exists if the bricks have lost their germinating power, excepting, of course, where they have been kept damp, and the spawn has spent its power, which is detected by the white threads appearing in great quantity.”

American-made Spawn.- So far as I have been able to find out by diligent inquiry, mushroom spawn is not made for sale in this country. But I am informed that a few growers do save and use their own flake spawn. Some of our principal growers, Van Siclen, Gardner, and Henshaw, for instance, in time past attempted to make their own spawn, but with only partial success, and now they confine themselves to the imported article. But this state of affairs can not long continue. The demand here for fresh mushrooms is so great, the industry of mushroom-growing so important, the price of imported spawn so high, and the quantity of foreign spawn imported annually into this country is so large, that, before long, we hope some one will find it to his advantage to make a specialty of growing mushroom spawn in this country to supply the American market. There is no practical operation in connection with the cultivation of mushrooms so little known or understood by the general grower as the growing (or “making,” as it is commonly called) and preserving of mushroom spawn. General cultivators in England and France (outside of the Paris caves) do not make their own spawn; it is a distinct branch of the business, and carried on by specialists who grow mushrooms for sale in winter, and spawn in summer.

The time and attention required to produce a small quantity of first-class spawn are worth more than the cost of the spawn at the seed store. In order to make spawn profitably we must make it in large quantity, and we need not attempt to make it unless we have good materials and conditions for its proper preparation, and will give it every attention possible for its best development.

Because spawn may be made in America is no reason whatever why the American people will buy it. We must produce, at least, as good an article as the best in Europe before we can find countenance in our home market. It is not the shape of the manure brick, its size, fine finish, hardness, softness, or freshness, that counts in this case; it is the fullness and vitality of the mass of mycelium or mushroom plant that is contained within it.

HOW TO MAKE BRICK SPAWN

As the making of brick spawn for sale is not yet an American industry, but almost entirely confined to England, I think it best to restrict myself to describing how it is made in England. Mr. John F. Barter, of Lancefield street, London, is one of the most successful mushroom growers and spawn makers in Great Britain. He writes me that he confines himself entirely to the mushroom business; he makes his living by it. He grows mushrooms in the winter months and makes spawn in the summer months; he employs men for mushroom bed making from August until March, then, to keep on the same hands during summer, he makes spawn for sale. He grows for and sells in the London market about 21,000 pounds of mushrooms a year, and in summer makes some 10,000 bushels, equal to 160,000 pounds, of brick spawn for sale. The amount of spawn made in a year by this one manufacturer is about three times as much as the total annual importation of mushroom spawn of all kinds into this country. And he is only one maker among several. This fact alone must convince us that mushroom-growing is carried on to a vastly greater extent in European countries than it is here, where we have as good facilities as they have, and an immensely better market.

The manner of making the spawn differs a little with the different manufacturers, and no one can become proficient in it without practical knowledge. I asked Mr. Barter if he thought spawn could be made profitably in this country, paying, as we do, $1.50 a day for laborers, and without any certainty of the same men staying with us permanently. He writes me: “Uncertain labor would be of no use. Of course the wages you pay would not affect it much, as I pay nearly as much as that for my leading men. But to begin with, you must have a man that has had some experience.”

About the simplest and best way of making brick spawn that I find described is the following from The Gardeners’ Assistant. I may here state that Robert Thompson, the author of this work, was for many years the superintendent of the Royal Horticultural Society’s gardens at Chiswick, near London, and, in his day, was regarded as without a peer in practical horticulture, and lived in the midst of the market gardens of London and the principal mushroom-growing district.

“Fresh horse droppings, cow dung, and a little loam mixed and beaten up with as much stable drainings as may be necessary to reduce the whole to the consistence of mortar. It may then be spread on the floor of an open shed, and when somewhat firm it may be cut into cakes of six inches square. These should be placed on edge in a dry, airy place, and must be frequently turned and protected from rain. When half dry make a hole in the broadside of each, large enough to admit of about an inch square of good old spawn being inserted so deep as to be a little below the surface; close it with some moist material the same as used in making the bricks. When the bricks are nearly dry make, on a dry bottom, a layer nine inches thick of horse dung prepared as for a hotbed, and on this pile the bricks rather openly. Cover with litter so that the steam and heat of the layer of dung may circulate among the bricks. The temperature, however, should not rise above 60 deg.; therefore, if it is likely to do so, the covering must be reduced accordingly. The spawn will soon begin to run through the bricks, which should be frequently examined whilst the process of spawning is going on, and when, on breaking, the spawn appears throughout pretty abundantly, like a white mold, the process has gone far enough. If allowed to proceed the spawn would form threads and small tubercles, which is a stage too far advanced for the retention of its vegetative powers. Therefore, when the spawn is observed to pervade the bricks throughout like a white mold, and before it assumes the thread-like form, it should be removed and allowed to dry in order to arrest the further progress of vegetation till required for use. It ought to be kept in a dark and perfectly dry place.” I would add, do not keep it where it is apt to become musty or moldy in summer; also keep it in as cool a dry place as possible in summer, and always above 35 deg. in winter.

These other recipes are also given:

“1. Horse droppings one part, cow dung one-fourth, loam one twentieth.

“2. Fresh horse droppings mixed with short litter one part, cow dung one-third, and a small portion of loam.

“3. Equal parts of horse dung, cow dung, and sheep’s dung, with the addition of some rotten leaves or old hotbed dung.

“4. Horse dung one part, cow dung two parts, sheep’s dung one part.

“5. Horse droppings from the roads one part, cow dung two parts, mixed with a little loam.

“6. Horse dung, cow dung, and loam, in equal parts.”

From the above it appears that horse dung and cow dung are the principals in spawn bricks; the loam is added for the purpose of making the other materials hold together; it also absorbs the ammonia, which otherwise would pass off.

J. Burton’s Method.- From The Kitchen and Market Garden. Make the spawn in early spring. As cow manure is the principal ingredient used in making the bricks this should be secured before the animals get any green food. Store it on the floor of an open, dry, airy shed, and turn it every few days for a week or two. Then add an equal part of the following: Fresh horse droppings, a little loam, and chopped straw, mixed together. “The whole should then be worked well together and then trodden down, after which it may be allowed to remain for a few days, when it will be required to be turned two or three times a week. If the weather be fine and dry the mass will soon be in a fit condition for molding into bricks, which process can be performed by using a mold in the same way as the brick makers, or, ... the manure may be spread evenly on the floor to a thickness of six inches, and then be firmly trodden and beaten down evenly with the back of the spade. It should then be lined out to the required size of the bricks, and be cut with a sharp spade or turfing iron. In a few days the bricks will be sufficiently dry to handle, when they should be set up edgeways to dry thoroughly, and if exposed to the sun for two or three days they will be ready to receive the spawn. In introducing the spawn two holes large enough to admit a piece of spawn as big as a pigeon’s egg should be cut in each brick at equal distances. This should be well beaten in and the surface made even with a little manure. The bricks should then be collected together in a heap and covered with enough short manure to cause a gentle heat, being careful that there is no rank heat or steam to kill the spawn. This must be carefully attended to until the spawn is found to have penetrated through the whole of the bricks, after which they should be stacked away in any convenient dry place.”

How to make French (flake) spawn.

I can not do better than to let a practical Frenchman engaged in the business tell this story. In Vol. XIII of the London Garden I find an English translation of M. Lachaume’s book, “The Cave Mushroom,” and this comment by the editor: “The most complete account of the cave culture of mushrooms which has been published by any cultivator on the spot well acquainted with the subject is that recently published by M. Lachaume.”

Lachaume says: “The best spawn to use is what is called ‘virgin spawn’; that is to say, which has not yet produced mushrooms. In this country this kind of spawn may be procured of any respectable nurseryman, under the name of ‘French spawn.’ It differs from English spawn by being in the form of small tufty cakes, instead of in compact blocks. Large mushroom growers, however, always provide themselves with their own spawn by taking it from a bed which is just about to produce its crop, or which has already produced a few small mushrooms.... It is true that by thus ‘breeding in and in,’ as it were, the mushrooms show a tendency to deteriorate after a time; new spawn must therefore be obtained as soon as any signs of deterioration begin to manifest themselves.”

Making French Virgin Spawn.- Condensed from Lachaume’s book on mushrooms. Take five or six barrow loads of horse droppings that have lain in a heap for some time, and lost their heat, and mix them with one-fourth of their bulk of short stable litter. Then, in April, open a trench two feet wide, twenty inches deep, and length to suit, at the foot of, but eight inches distant from, a wall facing north. In the bottom of the trench spread a layer three to four inches deep of chopped straw, then an equally thick layer of the prepared manure, all pressed firmly by treading it down. The two layers must now be gently watered, and then another double layer of chopped straw and droppings must be laid, trodden down and watered, and so on until the top of the trench is reached. The bed ought to rise above the level of the ground and be rounded off like the top of a trunk. To prevent excessive dampness from heavy rain cover the mound with a thick layer of stable litter. Three months after filling the trench it should be opened at the side or end. If the pieces of manure are well covered with masses of bluish-white filaments, giving off the odor of mushrooms, the operation has succeeded, and the spawn is fit for use or for drying to preserve for future use. But if the threads are only sparingly scattered through the mass, the trench should be covered up again and left for another month. In saving the spawn the flakes of manure containing the largest amount of spawn filaments should be retained, and those showing a brown appearance rejected. In order to facilitate the drying of the spawn the flakes should be broken into pieces, weighing from one to two pounds; they are then placed in a well ventilated shed, but they must not be piled upon each other. Properly prepared and dried this spawn keeps good for ten years.

A Second Method- (by Lachaume). “This is generally adopted by mushroom growers. The formation of the spawn is accelerated by adding pieces of old spawn here and there.... At the beginning of April we must choose a piece of ground situated at the foot of a wall facing north.... The soil ought to be very open and light rather than heavy, so as to avoid dampness. Taking advantage of a fine day, we open a trench sixteen inches wide and at about eight inches from the foot of the wall, and of a length adapted to the quantity of spawn we desire to produce. The earth is thrown out on the side opposite the wall. Manure which has been prepared for a mushroom bed, and has just come into condition is then filled into the trench, leaving, however, a space at one end of it about two feet and six inches in length for the formation of a mushroom bed, which is made by tossing the manure about and shaking it up with the hands, after which it is pressed down with the hands and knees. As soon as the layer of manure reaches six inches in thickness we place along the edge a number of lumps of spawn at about one foot apart. These lumps are placed level with the manure on the edge facing the wall. This portion of the surface of the manure ought to be raised vertically, and should lean against the earthen wall of the trench. The other half of the surface ought to slope gently toward the wall, leaving a space of three or four inches between it and the side of the trench, so that it may be trimmed. The lumps of spawn on this surface should be placed a little backward, so that they may not be broken when the bed is trimmed. The bed is then covered with more manure, until the first lumps of spawn are buried three or four inches deep. A second row of lumps of spawn is then inserted, as described in the directions for making the first row, and the bed is filled up level with the surface of the soil. It is finished by covering it up with a layer of fine, dry soil three or four inches thick. The spawn ought to be very dry, otherwise we shall get a premature crop of mushrooms instead of fresh spawn. At the end of six weeks or a couple of months the new spawn ought to make its appearance, a fact which we may learn by opening the bed. One sign, which will save us the trouble of opening up the beds, is the appearance of young mushrooms on the surface. The layer of earth is first removed, and then the cakes of spawn are treated as described in the directions given for the first method of making spawn.”

Third Method- (by Lachaume). “By filling in a trench like that described in the first method, by a series of layers of one-third of pigeon or fowl guano, and two-thirds of short manure, containing a large proportion of spent horse droppings, treading it down firmly, watering it if it is too dry, and finishing up with a layer of soil, as described already, we may, at the end of a couple of months, or even a little longer, procure a supply of well-formed cakes of spawn of excellent quality, which may be used in the ordinary manner.”

From Mr. Robinson’s “Mushroom Culture.” “This (French) spawn is obtained by preparing a little bed, as if for mushrooms, in the ordinary way, and spawning it with morsels of virgin spawn, if that is obtainable; and then when the spawn has spread through it, the bed is broken up and used for spawning beds in the caves, or dried and preserved for sale.”

From Mr. Wright’s book on mushrooms. “French spawn ... is contained in flakes of manure. Neither is it virgin spawn, nor derived immediately from it, ... but is spawn taken from one bed for impregnating another.”

Relative Merits of Flake and Brick Spawn.- The flake or French spawn costs about three times as much as the brick or English spawn, and, as it is so much whiter with mycelium than is the brick spawn, many believe that it is more potent and well worth the additional cost. In spawning the beds I use two pounds of flake spawn to plant the same space for which I would use five pounds of brick spawn, and this gives a capital crop, with number of mushrooms a little in favor of the flake spawn, but on account of the larger size of the mushrooms the weight of crop is considerably in favor of the brick spawn. And I find more certainty of a crop in the case of the brick spawn than in the other.

Regarding the respective merits of brick and flake spawn, Mr. Barter, in response to my inquiry, writes me: “I have tried them both, and know brick spawn to be far the best. You see, I do nothing but this mushroom business for a living, so, of course, would use the best kind of spawn for my crop. Generally the French spawn produces one-third less mushrooms than does the brick spawn from the same length of bed, besides, those from the brick spawn are by far the heaviest and fleshiest.”

I would here observe that Mr. Barter’s remarks apply more to ridge beds out of doors than beds in the cellar or mushroom house. And it is odd, but true, that the flake spawn does not produce as good results in outdoor beds as it does in those under cover.