Growing Shiitakes is a simple process in a cold climate, and with some guidance you will be well on your way to fresh mushrooms. This process requires a shady spot, a few tools, freshly cut tree logs (not more than 3 months old), and Shiitake spawn. What is mushroom spawn you ask? Mushroom spawn is essentially any substance like saw dust or wood chips that has been inoculated with the mycelium of that specific mushroom.