The next important step is to properly carry out the so-called. thermal shock, consisting in a quick reduction of the temperature in the compost from 24…27°C do 17…18° C by introducing, by means of mechanical ventilation, a large mass of fresh air, which also causes the necessary reduction of CO2 concentration in the hall air. The shock is then carried out, when the hyphae are approx. 0,5 cm below the casing surface. If the shock is applied too early, the mushrooms set deep under the casing surface, and hence – they are heavily soiled and difficult to harvest. A shock carried out too late may cause the mycelium to "spill" onto the casing surface and the so-called. woolen, then mushroom fruiting bodies do not set up or set very poorly.
