Mushroom Blocks
Most medicinal and gourmet mushrooms are grown on mushroom blocks. Nowadays more and more people are realizing the power of mushrooms. That means there are more people than ever growing these mushrooms. Dope, I know! The medicinal and gourmet mushroom industry has more than doubled in the past 5 years.

What are mushroom blocks?
Mushrooms blocks are made from a form of carbon rich substrate that the mushroom mycelium can feed on and colonize.The most common substrate mix is known as the “Master’s Mix”, created by TR Davis from Earth Angel Mushrooms. You combine hardwood pellets and soybean hulls in a specific ratio. You could also use things like straw, wheat, oat husks, coffee grounds.
After sourcing your carbon source, you sterilize it, to kill off any pathogens. Next, you add mycelium to the blocks and allow it time to grow or colonize. When the mycelium has had time to colonize these blocks, you introduce them to proper conditions and then they fruit or produce mushrooms.
Often time growers will dispose of the blocks after one growing period, even though you can fruit the same block multiple times. This is because you usually get your biggest harvest on the first flush. After that, the spent mushroom blocks are thrown away.
This spent mushroom substrate is gold. If you can get your hands on some you should. This substrate is a blend of natural products that work wonders on a garden. There are still nutrients in this substrate even though it is being thrown away. What’s funny is most urban mushroom farmers do not have the necessary space to properly compost the spent mushroom blocks and are looking to get rid of it. They will often give it to you for free. It’s crazy you’re doing them a favor by taking it.That’s because if left unattended it can attract fungus gnat and Trichoderma, which is an enemy of mushroom growing. These things have the potential to contaminate an entire operation.
Here are some potential ways to use mushroom blocks in an urban garden:
Compost. Mushroom substrate is a top tier fungal dominated compost. Since mushrooms are fungus and we are inoculating and growing this fungus on these blocks. When composted these blocks produce a high quality fungal dominated compost. And we all known the benefits of fungal compost vs bacterial compost, right?
Mulch. By simply placing the spent blocks on the top of the soil they can act as a mulch, like compost. They can help keep weeds at bay and will continue to breakdown and feed the soil
Animal feed. Some of the potential substrate components are already being used as forms of animal feed. Whether straw, oat husks, or soybean, the ingredients can already be fed to livestock. So, the added fungi will have no harm on the animals
Biogas and energy. I have no firsthand experience with this. I have read stories about people using the spent substrate as an energy source for anaerobic fermenter. Bacteria could be propagated with the purpose of ingesting the SMS and converting it into methane gas. In theory, this sounds dope.
Bioremediation. There are many polluted sites and areas in the world. The way process of removing the toxins and revitalizing the land is called bioremediation. The SMS has the ability of absorbing pollutants. Then the microbes that inhabit the SMS could breakdown the absorbed pollutants as they work through the substrate.