During the bud-acceleration period of Shiitake, certain temperature difference, scattered light and air fit for the differentiation of primordium, hence Shiitake farmer should uncover the film on top of ridge, control the fruiting temperature to a range of 10-22 degrees and diurnal temperature difference to a range of 5-10 degrees. Besides, in case of small natural temperature difference, you could also artificially widen it with the help of ventilation in daytime and nighttime. On condition of 90% of superior relative air humidity, mushroom buds occur after 3-4 days or so.
During this phase, you should also eliminate too low space humidity and strain hydropenia, which may affect the formation of primordium. When the two mentioned phenomenons happen, you could increase the amount of water-spraying, each time after you spray water, be sure to air till the surface of strain is not slimy, then cover plastic film to preserve moisture. And lastly, once high-temperature and high-humidity circumstance arise, you should also immediately strengthen the ventilation.