Cultivating Mushrooms at Home

-Jesse Cerrato-

Interest in growing edible mushrooms at home is on the rise. Folks with foodie appetites looking for a different kind of hobby and a way to practice economical consumption are joining the movement. Not everyone is sure where to start, but we are here to help!

Just like with other aspects of gardening, it’s important to understand the needs and requirements of the species you want to grow. As an introduction, I will specifically cover how to grow Oyster mushrooms in an appropriate (indoor) environment.

First let’s cover a few key terms:

• Mycelium: Vegetative structure of fungus; similar in appearance to the root structure of a plant.
• Substrate: What mushrooms eat; substance acted on by fungal enzymes.
• Spawn bag: A substrate inoculated with mycelium, in this case sawdust in a filter bag.
• Inoculation: The act of adding healthy mycelium to a freshly sterilized substrate.
• Incubation: Process in which an inoculated substrate is allowed to grow at ideal growth conditions (temperature regulation to encourage fungal enzymatic activity).
• Colonization: Mycelial growth on a substrate over time.
• Enzyme: A protein that accelerates specific chemical reactions.
• Fruiting body: A fungal conglomeration also know as a mushroom; a dense network of fungal tissue capable of reproduction through spores.
• Flush: A group of fruiting bodies ready for harvest. Typically 3-4 rounds of harvesting per bag.
• Field Capacity: The maximum capacity that a substrate can hold water before it becomes oversaturated. (One or two drops of water fall out when a handful is squeezed) 

For folks wanting to get started, we recommend purchasing a pre-inoculated spawn bag. The spawn bags we produce at Resting Point Farms are made from locally sourced hardwood sawdust and organic wheat bran (plus a dash of gypsum for calcium and sulfur). In this case, sawdust provides the carbon, which consists mostly of glucose polymers called cellulose, and the fibrous parts of wood/bark, known as lignin. Nitrogen is obtained through the digestion of wheat bran, which is high in amino acids (important building blocks for all life). Sawdust and wheat bran are combined, hydrated to field capacity, then steam sterilized for 24 hours to kill off any competitor microbes. Once the substrate has cooled, it’s brought into the lab where myceliated grain spawn is added (inoculated) to the fresh sawdust and heat sealed to close the filter bag. Oyster mushrooms take about a month to fully colonize (healthy, white mycelium covering the entire substrate).

Now that you know what Oyster mushrooms like to eat, let’s go over how they are cared for:

Transforming a block of mycelium into a glorious cluster of fruiting mushrooms requires a basic understanding of how they fruit and what environment your particular strain of mushrooms does best in. So what are the variables here?

• Temperature: Different strains prefer different temperature ranges. This is a function of where the mushroom originally grew. Over time, strains of mycelium can be acculturated to growing in different temperature ranges, but this requires the cultivation of spores from successful fruiting bodies. It’s much easier to grow your mushrooms at their ideal range, or purchase a species that’s better suited to your environment. Conveniently, the variety of spawn bags we provide at Fifth Season are capable of growing at room temperature (Approx. 65-75°F). It is important to keep the temperature stable, otherwise mycelium can overheat resulting in the death of the mushroom. 
• Humidity: Mushrooms need constant, high humidity to develop properly. This requires a humidifier and a means of keeping a constant Relative Humidity (RH) between 80-90%. When a bag is first cut and placed into a fruiting chamber, the initial development of pins (tiny mushroom heads that form a fruiting body), requires a slightly higher RH (up to 95% RH). After a day or two this humidity should be adjusted to a approx. 80%. A higher RH results in faster mushroom growth while less humidity should give a more flavorful, slower growing mushroom.
• Frequent Air Exchange: Or FAE, is the act of blowing clean air across the growing mushrooms to encourage evaporation of excess moisture. I recommend using a small mounted fan on a recycle timer to allow for fine adjustments in the amount of time the fan is on vs. off. I’ve had the best results with setting my fan timer to 3-5 minutes ON for every 25-30 minutes of OFF time.Mushrooms breathe oxygen like us and exhale carbon dioxide. Abnormal development can result if CO2 levels get too high. Mushroom stems become too long and covered with hair like mycelium if they don’t get adequate oxygen. Caps become small and cup-like as well, so monitor growth and take notes!

Note-taking is one of the most critical aspects of mushroom cultivation. Keep a notebook by your fruiting chamber and write down the Temp., RH, and FAE every time you check on your mushrooms. When you log your observations, make sure you include a time and date so you can decide if your system needs adjustment.

Setting up your fruiting chamber: Every fruiting chamber is going to be slightly different, but the most important factor is that you keep your mushrooms out of direct sunlight. Mushrooms can be observed growing almost by the hour, so be patient if you make an adjustment to humidity or air flow, and wait a day before making any additional changes.

DIY fruiting chamber

• Gardman 4 Tier Mini Greenhouse $72.99
• 6” Hurricane Clip Fan$19.99
• Spartan Series Repeat Cycle Timer$44.99
• Basic Humidifier

Troubleshooting

One visual indicator of excess moisture is a constant dripping or streaming of droplets down the inside of your chamber. Ideally, the humidity inside should leave tiny little droplets that evaporate before they then collect into a drop.

Some people prefer to mist by hand (spray bottle) and fan with a piece of cardboard. You might have great success doing it that way, but having more control over your variables could give you greater insight into how the system works as a whole.

Watch out for mold! Other organisms compete for the same substrate as the mushroom species you are trying to grow. Some infections can be overcome by Oyster mycelium, but watch out for contaminations that take over too much of the bag. If this happens it’s not the end of the world, you can add spent blocks to your compost pile. This inoculation of fungus can speed up the time it takes for hardy fibers (lignin and cellulose) to breakdown.

Having the right equipment allows you to grow harder to cultivate varieties like Lion’s Mane, Shiitake, Maitake, and Reishi. Automating your grow reduces the amount of time involved in cultivation so you can focus on the most enjoyable part of harvesting fresh mushrooms- cooking with them!

For more information and expert advice on growing your own mushrooms at home, visit your local Fifth Season store!