Porcini mushrooms are a favorite in Italy, so much so that they are strictly regulated. They are considered a very fine variety of mushroom and are used in many delicious recipes. They are large in size and have a delicate, earthy flavor similar to hazelnut. Porcini mushrooms are hard to come by in the wild but can be grown at home with the help of porcini spores. As long as they are in a moist, humid environment, they will grow into mushrooms you can harvest and enjoy.
Cut a piece of corrugated cardboard so it is at least 2 feet in height and 3 feet in width. Corrugated board is thicker than regular cardboard. You should be able to see the layer of ribbed paper inside, providing air pockets.
Coat the ribbed side of the cardboard in the sawdust inoculated with porcini mushroom spores. Make sure the entire piece is covered in the substance. The mushrooms will use the cardboard and spores to grow.
Roll up the cardboard so it is in the shape of a folded soft taco. The sawdust-brushed side should be in the inside, protected by the rest of the cardboard. Duct tape or staple the ends together to keep the cardboard from unfolding.
Put the spores in a cool spot between 60 and 64 degrees Fahrenheit. Porcini mushrooms thrive in a humid environment, with about 95 percent relative humidity. If it's mild outside, and between 60 and 64 degrees F, you can put the cardboard rolls in a shaded part of your garden. The corner of a greenhouse is also preferable.
Spray the rolls every day to keep them moist. Porcini mushrooms need moisture to grow.
Wait for the mushrooms to achieve the desired size, then harvest them.