Once the bulk substrate has fully colonized and hyphal knots begin to form, it’s time to get the monotub into fruiting conditions. Start by sanitising the lid and base. Wear nitrile or latex gloves and put on a face mask.
Fill the longer holes in the monotub with polyfill, a common stuffing material used for pillows and cushions. This will block contaminants and increase humidity.
1. Substrate
While not typically thought of as such, substrate is a crucial component in any growing system, you can try the kits on Gro Magik. It’s the material on which plants, microbes, reptiles, and mushrooms grow and thrive. It is a medium through which they absorb water and minerals, provides energy in the form of sunlight or electricity, and provides a platform on which organisms can interact with their environment.
A good substrate provides the foundation for the growth of your crop and determines the quality of your final product. It can be a mix of manure, grain, or wood shavings, and is best prepared in advance for optimum results. A good substrate can make the difference between a bumper harvest and a disappointing one, so it’s important to spend the time and effort necessary to prepare the right materials.
The first step to successful monotub cultivation is to ensure you have the correct substrate, and the proper liner if using one (recommended). If you’re growing a common edible mushroom species like oyster or portobellos you should be able to purchase fully colonized grain spawn that is suitable for use with your chosen substrate in any grocery store. If you’re growing a more rare or difficult to find species of mushroom you may need to make your own grain spawn or create a custom inoculation mixture.
To prepare your monotub, sterilize it and then fill it with about an inch of bulk substrate to field capacity. Then sprinkle a thin layer of colonized spawn over the surface, and continue to layer the spawn and substrate in this manner until you reach the desired depth of your monotub.
After you’ve inoculated your monotub, put the lid on and place it in a warm, indirect light location until you see mycelium spreading throughout the entire substrate mixture. This should take about two weeks for most manure-based species, and up to three or more for grain- or wood-based substrates. Around this time you will also start to see dense knots of white mycelium forming on the substrate surface, which is known as hyphae formation and indicates full colonization.
To avoid contamination while you’re inoculating your monotub, put a few drops of rubbing alcohol into a spray bottle and sterilize the work surface, your hands, your monotub’s liner if you’re using one, your spawn bag, your bulk substrate bags, and any tools you might use to cut these bags open. This will help prevent unwanted contaminant from entering your fresh new growing environment.
2. Humidity
Keeping up with the proper ambient humidity levels is vitally important for a monotub grow. The bulk substrate will absorb water and mycelium during colonization, but it’s important to have a humid environment as well to encourage the growth of hyphal knots and primordial pins (additional mycelial growth that will eventually form fruiting bodies).
When the monotub is inoculated with mycelium, it’s best to keep it undisturbed for up to ten days to speed up colonization and avoid contamination. Be sure to keep it in a warm room, but not in direct sunlight. A temperature between 77 and 80 degrees Fahrenheit will provide the best conditions.
A hygrometer is a great tool for monitoring moisture levels. It will help you gauge the amount of humidity in your space, and it can be placed inside the tub to monitor mycelial growth directly as it happens. Depending on your ambient humidity levels and the species you are cultivating, your hygrometer may indicate that it’s time to mist your monotub or introduce other methods for increasing humidity.
Once mycelium has fully engulfed the bulk substrate, it will begin to elongate into long, thin filaments known as hyphal knots. These are the first stages of a fruiting body, and if they continue to develop, you will eventually end up with a mature mushroom crop.
In order to prevent side-pinning, which can happen when mycelium reaches the edges and bottom of the bulk substrate, block light from reaching those areas by lining your monotub with black spray paint or a plastic garbage bag. Cultivators often use a black contractor-type trash bag, cut so that it only covers the top half of the tub. Our friends at North Spore recommend this method for monotubs, as it is the easiest way to discourage side-pinning and block light from reaching the sides of the tub.
A fan is a great way to create a constant flow of air, which will ensure that your mushrooms have adequate oxygen for healthy development. You can mount a small computer fan on a cycle timer in front of the monotub to do this, or simply cut an additional hole for this purpose.
Older directions for the monotub technique often instruct cultivators to take off the lid to mist and fan the mushrooms/substrate multiple times a day. This can lead to contamination, and is generally unnecessary. Be sure to only open the monotub in the event that it appears to be very dirty, or if you smell a rancid, foul odor. This indicates that contamination has occurred. Be sure to wash your hands before and after handling the monotub, as this will help to prevent contamination as well. It’s also a good idea to wear latex or nitrile gloves, as they will be more resistant to mycelial contaminants than other gloves.
3. Light
A monotub fruiting chamber is a popular option for growers of all skill levels who prefer a minimalist setup. These simple mushroom cultivation methods require minimal space and can produce large yields. The basic monotub setup can be easily modified to suit a variety of different mushroom species and cultivation requirements. For example, an easy-to-use fresh air exchange fan can be installed to prevent CO2 buildup in the monotub. This allows you to cultivate a wider range of mushrooms, including those that thrive in high levels of fresh air.
The traditional monotub is made from a large clear plastic tub that has been drilled with holes for air flow. A cover is then placed over the top and a lid is screwed on. This simple, yet effective, mushroom growth method is popular among growers because it requires less work and equipment than the all-in-one bag fruiting chamber and PF Tek cake method.
Mushrooms need light in order to fully develop and mature into fruiting. During the early stages of colonization, light helps the mycelium spread and grow throughout the substrate. Once the mycelium has spread through the bulk substrate, hyphal knots begin to form. Hyphal knots are the first signs of a mushroom fruiting body forming. The hyphal knots then begin to grow into mushroom pins.
Light is also important for directing the mushroom pins in a certain direction. When the mushroom pins are oriented in a certain way, they are ready to be harvested. Most psilocybe species of mushrooms need to be harvested before the pins flatten out and lose their color.
The final step of the monotub fruiting chamber technique is to spray the top layer of the casing, sidewalls and lid with sanitized water one to three times daily. The spraying helps keep the monotub moist and promotes healthy pinning. It’s best to store the monotub in a dark area that isn’t directly exposed to sunlight, as excessive heat can dry out the mycelium and encourage contamination.
To keep the monotub moist and prevent contamination, it is helpful to use a fresh air exchange fan that is connected to a cycle timer. This allows you to regulate the fan’s cycle duration and frequency, tailored to the specific needs of your mushroom species.
A fan is an essential addition to the monotub if you want to grow more advanced and hardy mushroom species like lion’s mane, enoki or blue oyster. This modification also allows you to grow other types of edible mushrooms that enjoy high levels of fresh air. The classic monotub setup uses passive air exchange through filtered holes, which can lead to carbon dioxide buildup in the monotub and limit your options to species that tolerate this. By using a fresh air exchange fan, you can avoid this issue and create a more diverse and successful monotub fruiting chamber.