Phase 3, also called the spawn-run process, is the last phase of the substrate creation. As for infection sensitivity the point between phase 2 and 3 is the most critical one.
. After phase 2 we have a completely sterile product. However the substrate has to leave the tunnels to be inoculated. So it is vital to keep the production facility in which this takes place sterile. In this process the spawn is being added to the compost. This spawn is already inoculated and grown on a pre-sterilized grain of corn. This grain of corn is the first nutrition of the [mycelium] so it can survive until it is being added to the substrate. These grains of corn are called spawn and is proved to Walkro by specialized companies. This spawn carries the genetic attributes of the mushrooms.
After this procedure the substrate is put back into the same tunnel as the phase 2 tunnel. At a temperature of 25 to 26° Celsius the mycelium will slowly grow from the grain of corn and colonise itself on the substrate. After 15 to 18 days this process is being stopped and the substrate reloaded for transport to the customer. In the case of Pilzhof Wallhausen GmbH, it is relocated to the culture spaces for phase 4. Special supplement is being added again during reloading. This supplement is nitrogen rich and is an extra nutrition for the mushroom. This supplement is mostly based on soya and provides an extra 15% gain to the mushrooms growth.