Probable causes:
1. Unfit temperature: After spawns become fully-grown in compost, they quickly form buds under suitable room temperature, too high or too low temperature inhibits the formation of primordia.
Handling methods:
A. Moderately sow in accordance with different requirements on mushroom varieties.
B. Enhance the pressure: When spawns have grown to certain degrees, put several dry pebbles on the surface of fungus bed, then mushrooms would grow between the gaps.
C. Exposure: You could utilize the luminous effect of mushroom to moderately provide illumination, which facilitates the formation of sporocarps.
D. Too high humidity on fungus bed, poor ventilation or improper dosage of Nitrogen causes vain growth of mushroom. Under that circumstance, you could utilize iron wares to harrow on the surface of compost and remove old spawns,finally press tightly. Meanwhile, be sure to keep heat and moisturize so that you stimulate the formation of sporocarps.