Richters InfoSheet D8655  

Shiitake Mushroom Kit Growing Instructions

The shiitake mushroom (Lentinus edodes) prefers cool temperatures (45-70 degrees Fahrenheit, 7-21 degrees Celsius), and a high humidity (75-85% relative humidity). It requires light – direct sunlight is too strong, but “skylight”, or light from a fluorescent lamp up to about 15 ft. away, is fine. It requires fresh air, but, a lot of air movement will tend to be too drying and may sweep away too much of the carbon dioxide produced by the growing mycelium.

In a less than perfect environment, it is beneficial to keep the bag on the substrate block as much as possible, to minimize the drying and maintain slightly elevated carbon dioxide levels. Open the top of the bag a little, to allow for increased ventilation which helps to induce fruiting (“pinning”) but minimize drying. The substrate surface should be moist at the times when flushes of mushrooms are wanted. When small mushrooms are evident, open the op of the bag a little more. As the mushrooms develop a little more, slit the bag down the sides of the substrate block to provide room for the expanding mushrooms and to provide more ventilation. If mushrooms appear down the sides of the block under the plastic, then slit the bag at that point, but do not cut the surface of any developing mushrooms or the surface of the block.

During damp, cool weather they will grow well outdoors, if protected from direct sunlight, hard freezing, slugs, snails and crawling insects. Forced air heating or a drafty location indoors may cause excessive drying. Constructing a “tent”, in the form of a large, clear plastic bag placed loosely over the top, or poly supported by wire or sticks may be necessary. When dry conditions prevail, you may need to mist the inside of the tent (remember that cold weather outside may result in low humidity indoors). As a method of keeping your mushrooms humid, frequent misting directly onto them is not a very satisfactory approach and often leads to bacterial problems.

Although they may benefit from an occasional drenching, mushrooms must not remain continuously wet, or they will rot. Often, drenching the pack by holding it under a tepid shower for a minute or two at the start is beneficial. Mushrooms should be ready to harvest in 2-3 weeks. After a heavy harvest the block will have lost much moisture. The water may be replenished by immersing the block in cold (35-50 degrees F) water for 4-8 hours. The soaking water should be as cold as possible. Immersion in warm water for more than a short time may damage your mushroom plant. Warm water does not carry as much dissolved oxygen as cold water and at the same time the mushroom’s need for oxygen is greater in warm water. Drain the block well, and place it in a clear poly bag with about ten 1/4" holes in it, so that it will have a little fresh air and slowly dry out. More mushrooms should appear within 2-4 weeks. If none appear, fruiting may be encouraged by thumping the block down 3 or 4 times on a table. The open the bag for increased ventilation. The reactivation cycle may be repeated 3 or 4 times or more.

Soaking or thumping is sometimes necessary to start the mushrooms initially, if the block has dried out too much before you start to fruit it. Soak in very cold water (a long soak in warm water will damage your mushroom plant) for 4-8 hours. If the surface of your mushroom block is mostly white coloured when you receive it, then it may need to “mature” for a few weeks before it will be ready to brown. Maturing occurs under normal fruiting conditions (55 to 75 degrees F). Some light is essential for maturation. Shiitake mushroom mycelium will be killed at a temperature of about 100 degrees F (just above body temperature), so be careful during hot weather and do not place your plant in direct mid-day sun. Freezing temperature should not damage your shiitake plant unless it is very wet – such as when we ship it to you. If the block has lost a lot of moisture while it matures, it will likely be necessary to soak it.

The Shiitake has an excellent flavour and texture, reminiscent of meat. It makes an excellent addition to soups, stews, stir fries, etc. Dried shiitake chips are a real treat, although strong flavoured. Harvest when white, cottony veil beneath the cap has fully broken away from the stem or, if you want really large mushrooms just let them grow. The substrate on which your mushrooms are growing is made of hardwood dust supplemented with millet grain, rye grain, wheat bran and crushed limestone. No pesticides or chemicals have been added to the medium.

During warm weather, mushroom flies can be a problem. Scraping off any patches in which the larvae are observed will help to control them.

Please Note

This shiitake spawn requires a pre-incubation period of approximately 3 weeks at a temperature of 60-75 degrees F, with some exposure to (low level) light, in as clean a place, prior to fruiting. Humidity is not usually a problem at this stage as the poly bag protects the clock of substrate from drying. However, damp dirty environments often have populations of mites and insects which may infest your fit. During this period the block of sawdust-wood chip substrate will develop patches of brown as it matures. Towards the end of pre-incubation, the sides of the clock will also develop bumps and cracks.

If mushrooms have not started to develop by about 5 weeks, then give the bag a light thumping on a counter top and handle for fruiting as described in the instructions. Temperature changes within the range of about 50-65 degrees F will help to promote “pinning” at this stage. The optimum temperature for colonization and maturing (65-75 degrees F) is a little high for “pinning: (initiation of the fruiting process), and the block should be placed in an environment with a temperature in the range of 45-65 degrees F for pinning and fruiting. high humidity (65-85% relative humidity) is necessary at this stage. Giving the substrate block a thump on the table top will also promote pinning. If mushrooms start to form under the bag, then slit the bag down to that point to allow the mushrooms to expand. Be careful not to cut the developing mushrooms.


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D8655   ©2000 Otto Richter and Sons Limited


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