MUSHROOM: How to Grow It Successfully Outdoors and Indoors
The cultivated Mushroom (Agaricus campestris) may be grown indoors in sheds, cellars, or properly designed Mushroom houses, almost all the year round, and outdoors in beds or in lawns or meadows during summer.
Indoors, the chief essentials are: scrupulous cleanliness, excellent ventilation, 80 per cent humidity, a temperature of 50-65 degrees F., but never below 40 degrees or above 70 degrees at any time. Darkness is not vital, but it is desirable. A bed begins to yield 6-8 weeks after spawning and casing, and will crop 3-4 months, giving 8 to 12 oz. per sq. ft.
Mushroom House. The properly designed Mushroom house or cellar is dark, well ventilated and insulated to give even temperatures, with a central pathway and space for the beds on each side. A site sheltered from cold winds is desirable. A level floor of earth, dusted with lime, is best. Adapted buildings should be rain-, draft- and vermin-proof. Some artificial heat is necessary in the colder parts of North America for winter crops.
Propagation is effected by spawning or impregnating beds of fermenting manure or organic compost with a pure culture containing the spores of the fungus. Pure culture spawn has superseded the old-fashioned brick spawn and is supplied in the forms of small blocks or cylinders or powdery particles, with the maker’s instructions.
Materials for a Mushroom Bed. The best material is fresh stable manure from horses fed on corn or oats, and bedded on straw, preferably wheat. Manure from sick, medically treated horses is not desirable, and that of horses fed on grass, hay or roofs will not give the best results. Ideally, the manure should be half droppings, half short straw. Long straw should be shaken out.
To prepare, stack the manure on a clean disinfected site in a heap 4-5 ft. square and 5 ft. high, watering each foot layer with a fine spray, adding 1 teaspoonful of Lysol to each 2 gallons of water. The heap will heat up. When it begins to sink after 7-8 days, turn top to bottom and sides to middle and remake, shaking and breaking any caked lumps with a fork. The heap should be moist, but not wet. Any burnt or dry portions should be watered. Turn again after 3-4 days, and repeat turning up to 4-5 times until the whole heap is free from obnoxious smell, is rich-brown in color, and yields hardly any moisture when squeezed.
Mushroom Bed Compost. When stable manure cannot be obtained, mushroom-bed compost may be made from organic materials such as straw decomposed by a special chemical activator. The manufacturer’s instructions should be strictly followed.
Making the Beds. When ready, the compost may be made into beds, either flat or of ridge type, or on shelves. Flat beds are most suitable for indoors. They should be 4 ft. wide, 9-10 in. deep in summer, 12-15 in. deep in winter; on shelves, they may be 8 in. deep. The shelves are arranged in tiers, and are made of hardwood, treated with wood preservative. They usually consist of 1-1 1/2-in.-thick planks on suitable supports and 4 in. by 2 in. uprights, readily dismantled for cleaning purposes.
Ridge beds are essential outdoors, and may be used indoors, being 30 in. wide at the base, tapering to 6 in. at a height of 24 in., and as long as necessary. If desired, smaller ridge beds can be used indoors.
The compost is shaken and stacked evenly when the bed is made, and firmed evenly and smoothly by treading on a board and pounding down with a block of wood to the finished depth. A ton of compost gives 50-60 sq. ft. of bed. The bed will heat up, and the temperature should be checked with a hotbed thermometer. Ventilate well to counteract sweating. When, in a few days, the temperature falls to 70 to 75 degrees F., the bed is ready for spawning.
Spawning consists of inserting pieces of spawn, about walnut size, 1 in. deep, 10 in. apart, in the prepared bed with a trowel, and firming the compost around the spawn afterwards. The bed may then be covered with straw, especially if the weather is cold.
Soiling or Casing. In 7-9 days, when the spawn is sending tiny threads of mycelium out, the bed must be cased with soil. A sandy soil is best, and it should be pure subsoil. If topsoil is used, it should be sterilized, and free from chemical fertilizers or vegetable matter. The soil, whatever its source, is mixed with an equal bulk of moist sifted peat. It is applied 1 in. thick to indoor beds, 1 1/2-2 in. thick to outdoor ridge beds, and finished smooth but not beaten hard to form a crust.
After casing, cover with straw, 4 to 12 in. thick, according to the weather. Out-of-doors, the straw needs to be 9 to 18 in. thick, and covered with burlap.
Management. At first, it is wise to keep the beds rather dry. In watering, the aim must be to damp the soil without wetting the manure compost. The beds need watering every 7 to 10 days, using a salt solution (2 teaspoonfuls per gallon of water), and a fine spray. Paths and walls should be damped down in warm weather.
The first Mushrooms may be expected in 6 to 8 weeks, appearing first in groups at the point of spawning, and later over the whole bed. The crop should be gathered frequently, the Mushrooms being twisted and then pulled free. They should not be cut to leave remains that would decay in the soil.
When a bed ceases to yield profitably, the old compost should be cleared out, the station disinfected or sterilized, and a fresh bed made up. The old compost is excellent for enriching the garden or for use in potting soil compost.
When to Start. The most favorable time to make up Mushroom beds is in June-July for late summer or autumn cropping. For a succession, beds can be made monthly until the spring.
The Outdoor Mushroom Bed. This should be made on a sheltered, well-drained site, preferably in June-July. If necessary, the bed may be made on a plank base, raised above the ground. The ridge type of bed is made, spawned, cased and strawed as for an indoor bed. The straw may be thicker, especially in the cooler weather months, and a tarpaulin cover or semicircular sheets of corrugated iron may be used to give increased shelter from wind and rain. One ton of manure gives a ridge bed three yards long. After cropping, the site should not be used again for mushrooms for two years.
Mushrooms in Turf. Growing Mushrooms in a lawn or meadow is a gamble, as so much depends on weather conditions. The simplest method is to take out small squares of turf, 1 1/2 in. thick; then remove 3 in. of soil and replace it with tightly packed lawn mowings or freshly made Mushroom manure compost. Water and insert pieces of spawn, then replace the turf. Late May, June and July are the times to do this, and Mushrooms may appear 8-12 weeks later. In a meadow, it is often sufficient to lift the turf in late May, insert spawn 1 1/2 to 2 in. deep, and replace the turf. A few pieces of spawn may always be inserted in old hotbeds or beds used for Melons or Cucumbers, or any soil or bed which has been kept liberally mulched with organic material.