Soil.
—The soil best suited for the growth of mushrooms is one rich in decayed or decaying vegetable matter. Mushrooms are often found growing in localities where a log or stump has decayed or where the inorganic matter from the manure of cattle or horses has been distributed on the soil. Artificial beds for the growth of mushrooms are made up largely of organic manurial substances.
Spores.
—Mushrooms are grown from spores. The mushroom produces a brown powdery material which consists of almost innumerable simple cells of ovate shape to which the term “spore” has been applied. A spore is not in the strict sense of the word a seed, but simply a cell which by proliferation produces the new fungus. Generally growers do not use these spores directly in seeding mushroom beds. Each complete spore, however, is, under favorable conditions, capable of proliferation or germination, producing a thread-like growth of a spider-web character which penetrates through the soil, prepared and manured, upon which a spore is germinated. This spider-web-like growth, in the common language of mushroom growers, is called the spawn, more properly called the mycelium of the mushroom. When the conditions are favorable, there are formed on the threads of this mycelium small nodules, which are the earlier stages of the complete fungus itself. From the beginning of this growth until the final production of the mushroom two or three days or even a week may elapse. The earlier periods of this growth take place under ordinary circumstances, but the advent of a warm rain or other extremely favorable conditions causes the budding mushroom to grow at an enormously rapid rate. The mushroom may not be said to have a root, stem, and leaf, as is the case with an ordinary green plant, but is practically a single organism, assuming different shapes which are represented by the different varieties and species of growth.
Differing Varieties of Edible Mushrooms.
—There is a very large variety of edible mushrooms differing in form, size, and shape from the Agaricus campestris. In the Washington markets there are four principal kinds of mushrooms which are found growing wild in the vicinity of the city. These comprise the common mushroom—Agaricus campestris, the horse + mushroom—Agaricus arvensis, shaggy mushroom—Coprinus comatus, and the puff-ball—Lycoperdon cyathiforme.
Conditions of Growth.
—The proper shed or cellars having been selected, the first thing to do is to see that the temperature is favorable to the growth of the fungi. Temperatures above 60 degrees F., or below 50 degrees F., are not favorable to the growth. The best temperatures are from 55 to 58 degrees. The locality where the mushrooms are grown should be kept very damp and the air highly saturated with aqueous vapor. The reason that mushrooms grow best in covered places, such as has been mentioned, is due to the particularly favorable influence which the even temperature mentioned and a practically saturated atmosphere have upon the growth. In localities where the changes of temperature are not very severe, mushrooms grow very well in the open. In the county of Kent, England, I have seen mushrooms growing in the open garden, where, by covering with straw, they flourish during the greater part of the year. In the winter time the temperature may be kept quite even by the covering to make abundant crops, while in the months of August, September, and October they grow in the open in great abundance.
Preparation of Seed Bed.
—The seed bed for the growth of mushrooms, as has already been indicated, is made principally of well decayed stable or stall manure. The manure must be well fermented, thoroughly disintegrated, and exposed for a sufficient length of time to be in the proper condition. Mushrooms cannot be obtained until the heat attending the fermentation of manure has entirely disappeared.