Growing Mushrooms 101

Growing Mushrooms 101

How We Prepare Our Kits. 

I hear from lots of people who are fascinated about the process of growing mushrooms, and want to learn even more, especially after trying our grow kits. Our grow kits are a great way to start but we’ve done all the work for you :) They’re designed that way so that you can go on with your busy lives while your mushrooms do their thing in the background. But for some of you that are curious, I wanted to make this blog post and go over some of the basics of cultivating mushrooms, with the focus on oyster mushrooms of course. 

My hope is to provide a window into the process, which should hopefully be both educational and inspirational. Many friends have made the comparison to it being like a science experiment, and we agree. Growing mushrooms is a giant experiment, and we’re always learning! 

Preparing our mushroom grow kits involves four key steps: spores, spawn, substrate, packing, and fruiting. 



Mushrooms grow from spores (not seeds). Spores are so tiny that you can’t see them individually with the naked eye. If you’ve tried one of our grow kits, you’ve probably noticed the fine dust that ends up accumulating around your grow kit once the fruits have matured. That dust is comprised of thousands of spores. Spores contain genetic material, cytoplasm, enzymes, acids, and ribosomes. Just like trees reproduce through seeds in their fruit, fungi reproduce through the spores that emit from the gills of mature mushrooms. Fungi spores get dispersed through wind or rainwater.


You can buy spore prints or spore syringes for many different species of mushrooms, but not all mushrooms can be cultivated at home. Those spores are used to create what we call spawn. Spawn can be myceliated grain, sawdust, and wooden dowels (plugs and pegs). Grain spawn is made from a variety of grains depending on the strain of mushroom you’re trying to grow. Sawdust spawn consists of mycelium grown into hardwood sawdust. Plug spawn is wooden doweling colonized with mycelium of a specific mushroom that grows on logs. Once you have the spores for the type of mushroom that you want to grow, you will need to create spawn. For oyster mushrooms, we make our grain spawn with whole oats and proso millet that have been soaked in water to retain the maximum amount of moisture and then sterilized in jars. We then inject the jars with the spores using the spore syringe (the lids of the jars usually have a hole drilled into them for air exchange and also give us access for the syringe). Of course this is all done in a 100% sterile environment to avoid any kind of bacterial contamination. 

Fully colonized pink oyster grain jar:

pink oyster mushroom grain spawn jar


Once the jars have been inoculated, they are stored in a dark room to allow the spores to germinate and become mycelium, and to start colonizing the grains. Mycelium is the root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Taken together, myecelium composes what's called a “mycorrhizal network,” which connects individual plants together to transfer water, nitrogen, carbon, and other minerals. This underground web connects plants and trees, and even serves as a mode for communication. The worlds largest organism is the mycelium network of the honey mushroom in Oregon’s Blue Mountains. These mushrooms would stretch to almost four square miles if laid flat, and they cover more than 2,300 acres. 

In about 1-2 weeks (depending on the strain), the jars are completely colonized and ready to introduce to our substrate. In our case, we use pasteurized straw but sawdust is also a popular choice amongst growers. Our straw is cut into small pieces and then pasteurized. Why pasteurized and not sterilized? Pasteurization eliminates the bad microbes like insects, other fungi, mold, and bacteria. We do not completely sterilize the straw, which allows us to selectively kill pests that will compete for food or directly attack the mushroom while minimizing the loss of good microbes.

Mycelium on straw:

Pink oyster mushroom mycelium and straw


Once the substrate is pasteurized, it’s mixed together with our colonized jars of grain spawn and packed into our grow bags, which are then placed into the grow box. The mixture is packed quite tightly to make it easier for the mycelium to colonize the entire bag. This is the final step of the process. Once these bags are colonized they will be ready to fruit and release their spores and start the whole process again and again.

sierra oyster mushroom grow kit



The final step in this process is for the fungus to begin it's fruiting cycle. The three factors that will take the substrate from a vegetative stage to a fruiting stage are temperature, oxygen level, and humidity. Controlling all of these at the right time will cause the substrate to fruit. Lucky for us, oyster mushrooms are quite tolerant when it comes to their fruiting conditions. They don’t require too much humidity and they love the fresh air, which is why you don’t really need a fruiting chamber for this strain. Unless you live in a particularly dry area, you can fruit these mushrooms right out in the open. If it’s too dry in your home, you will notice that the mushrooms will start to dry out a little and even start to crack, this is a good indicator that you should mist your mushrooms and try to bring the humidity up. 

In nature, when you see a mushroom anywhere, it means that there is whole mycelium network underneath it that has matured enough to start fruiting. That mycelium network knows to start fruiting once it reaches the surface because it starts receiving sunlight and fresh air. This is why our grow kits only fruit from the holes in our boxes where the substrate has access to air and not from random places. 

Nature is wild! The more you learn about it the more fascinating it is.

Hope you found this helpful :)

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