Growing mushrooms indoors on blocks is a great method to grow wood-loving species of mushrooms, with a quicker yield and more consistency than outdoor log cultivation, which can take a year or more to produce a crop and depends on the whims of the weather conditions at the time. Whereas blocks can begin fruiting in as little as a few weeks. Block cultivation is the primary method of production used by small to large-scale commercial growers of gourmet and medicinal mushrooms asides from button mushrooms that grow on compost.
The goal of block cultivation is to provide a good substrate for the mycelium to grow on. This is generally comprised of sawdust or fine wood chip, mixed with an additional (optional) nutrient supplement like wheat bran or soy hulls. The substrate mixture is hydrated, sterilized, and then inoculated with grain spawn or liquid culture of the desired mushroom species, before being incubated until it is fully colonized, at which point the sawdust can be put into fruiting conditions to grow mushrooms.
1) Sawdust or fine woodchip or Hey/ Straw. This can be purchased, or ‘homemade’. The key thing about the wood material is that it is clean, fresh, and free of excess bark and leaves. As a rule of thumb, hardwoods are preferred, although success has been had on pine as well. A common choice of substrate is compressed firewood pellets or blocks.
2) Nutrient supplements. Nutrient supplements are optional. They increase yield by boosting nutrients, but these extra nutrients also increase the risks of contamination.
Once your blocks are fully colonized with mycelium, they're ready to fruit. Fruiting areas can vary massively in their size and level of complexity.