Porcini mushrooms have a nutty flavor, and are a staple of gourmet cooking. There are several different species of porcini mushrooms, but the most common is called the king bolete. These mushrooms can grow to 12 inches, have a large cap and are brownish in color. Porcini mushrooms sprout naturally in hardwood forests near pine, chestnut and spruce trees, and are located throughout the world, including the United States, Italy, Europe, South Africa and New Zealand. Although these mushrooms are expensive to purchase from stores, you can grow your own at home with some planning and the right growing environment.
Soak the cardboard in water. The cardboard is ready when it is pliable enough to bend or roll.
Separate the cardboard. When wet, the cardboard will peel apart into two equal pieces.
Coat the ribbed side of the wet cardboard with the sawdust inoculated with porcini mushroom spores, using a putty knife.
Roll the cardboard into the shape of a tube and fold the ends toward the middle of the tube.
Secure the rolled cardboard with duct tape to prevent the tube from unraveling.
Place the mushroom spores in a location with an average temperature between 60 and 64 degrees Fahrenheit, and a 95-percent humidity level.
Keep the cardboard moist by spritzing it with water in a spray bottle.
Harvest the mushrooms when they have reached your ideal size. The mushrooms will begin to grow in three to four weeks.