The interest in all things fungi, and in particular, a curiosity about their medicinal benefits, has been rapidly growing in the past few years. This curiosity has led more people to take an interest in mushroom cultivation, an odd but equally consuming hobby quite unlike gardening, and in many ways more akin to cooking or, even more so, fermenting. From spore print to spore syringe to agar cultures, the process of growing mushrooms is a journey with its own language and skill set; the end goal being food, medicine, transformation, or even decoration.
For those new to mushroom cultivation, one of the immediately confusing aspects is the terminology. There is a whole new language around strains to learn – maybe you are just looking for Golden Teachers, but you encounter a variety of APEs, TATs, PEs, and Enigmas — which can be confusing, let alone the plethora of methods, techniques (teks), and equipment, all of which can be overwhelming. Hopefully, some of these DoubleBlind articles are helping you familiarize yourself with the space.
Despite the confusing terminology, growing mushrooms is actually quite easy. You can read numerous HowTo’s online, buy books, buy kits, join courses, or use a Mushroom Cultivation Journal. If you are new to growing mushrooms, one of the easiest and most reliable methods is to grow them in a monotub. In recent times, Monotubs have become somewhat of an essential item in indoor mushroom cultivation.
What is a Monotub
If you are new to mushroom cultivation, you might be wondering: What is a “monotub”? At its most simple, a monotube is a plastic storage container. With a few modifications, some micropore tape (or Tyvek), the storage container can be used in a growing technique where the whole container is used to house the mushroom “grow” – the term used to describe the substrate and developing mushrooms. The container is typically lined with black plastic containing a layer of substrate (about 5 to 10 cm thick), the plastic trimmed to just above the level of the substrate, and a series of holes to help with airflow. The mushrooms are allowed to grow freely within the container, requiring little more than an occasional misting if needed.
Monotubs have become so ubiquitous that in addition to prepared tubs being available as part of mushroom growing kits, people are also now selling inflatable kits! You can also be really guerrilla with your tub, recycling your old storage tubs, or even the ones you find at your local recycling depot — a great way to upcycle some of those plastic containers!
READ: Mushroom Gummies 101: Here’s Everything You Need to Know
What type of fungi do you want to cultivate? Monotubs don’t work for all types of mushroom cultivation, and are best suited to fungi that grow upwards, such as white button mushrooms i.e., Agaricus, king oysters, Ganoderma, Psilocybe cubensis, and a variety of other species. Species that grow from the sides of trees, such as lion’s mane or turkey tail, won’t work in a monotub – oyster mushrooms being the exception due to how versatile they are.
How many fungi do you want to grow? Monotubs are for bulk grows. Depending on various factors, including species or strain, you may get a couple of ounces to half a pound.
A History of Monotub Cultivation
The cultivation of Psilocybe cubensis was first popularised in the 1970s. Dennis and Terrance McKenna, writing under the nom de plumes O. T. Oss and O. N. Oeric, with illustrations by ethnobotanist Kathleen Harrison, published the Psilocybin: Magic Mushroom Grower’s Guide in 1976. The book explained how important sterile techniques were to mushroom cultivation, introducing aseptic inoculation and describing their methods for controlled indoor mushroom cultivation. It is notable that most books during this period described growing from jars.
Amateur Mycology grew into its own throughout the remainder of the 1970s, into the ‘80s, and the psychedelic renaissance of the 1990s. The appearance of online mycology forums during the late ‘90s and early ‘00s encouraged the exchange of information and cultivation techniques. Early mushroom cultivation guides mentioned growing from jars and trays, so using containers for fruiting was a natural evolution.
At the beginning of the 1990s, the main technique being spruiked was the PF-Tek, which involved growing mushrooms from cakes of substrate in terrariums with regular misting and manual fanning when possible.
Many who used the PF-Tek eventually graduated to ShotGun Fruiting Chambers, invented by Marc R. Keith (aka RogerRabbit). This type of fruiting chamber is now ubiquitous and widely used as small fruiting chambers. The moistened perlite in the bottom provides constant humidity and airflow. The large surface area of the perlite allows for constant evaporation. Because moist air is lighter and less dense than dry air, it rises, creating natural air currents.
The first documented reference to monotubs as a cultivation technique was in 2006 when Shroomery member Ohmatic described their method. Monotubs quickly gained popularity due to their simplicity and effectiveness; they were a simple, straightforward, and cost-effective method that streamlined cultivation for many.
There are now many online instructions on how to make monotubs, with people selling kits of premade monotubs of their own design and even a blow-up monotub!
Before You Build — Prep and Things to Consider
Key points: Go for clear plastic tubs and consider the size of the tub you need.
You are looking for clear plastic storage tubs; they are sold cheaply and come in various sizes with clip-on lids, and commoly found at hardware or homeware stores. They are easy to sanitize and designed to be stackable, the clear plastic allows light, and the soft plastic means they are easy to modify as long as appropriate care is taken.
When choosing a monotub, consider the space you need for the type of mushrooms you are growing and the expected size of the mushrooms. Short squat containers will likely not have enough height unless you grow Cubensis varieties that grow as “squats” or are heavily mutated, like Enigma. Alternatively, if you are trying to grow Ganoderma antlers, you may want a really tall container! It is also a good idea to consider where to store your Monotub(s) during myceliation, as 50-litre tubs can take up a bit of room. It is not uncommon for growers to have dedicated spaces with room for shelving to store various tubs.
This brings us to another factor: light. Stories about mushrooms needing to grow in the dark are myths. In reality, mushrooms need light as a fruiting trigger and also to help color their caps. Choose a tub made of clear plastic–many of the cheaper variations are typically made from clear plastic, but some of the more sturdy tubs can be almost opaque.
Before You Grow
Growing mushrooms is generally a stepwise process – a process in which Monotubs come somewhere near the end. As alluded to in the introduction the process is; spores to agar to liquid culture to spawn to monotub. Given all the options available now to beginner growers, a key point in the decision making process is at what part of the cultivation journey you are and how you are accessing your “spawn.” “Spawn” is a descriptive term that describes mycelium when it has been grown on grains – these grains allow a little bit of magic by contributing nutrients to the overall grow… a lot of nutrients! There are a few points along the journey to consider depending on your experience level:
- Purchasing pre-inoculated bags. All you need to do is mix the spawn with a bulk substrate and fruit it – this could be oyster mushrooms, reishi, agaricus, the list goes on. Sourcing Psilocybe like this may be a little harder, hence:
- Purchasing pre-steralized bags of grain and bulk substrate. All you need to do is inoculate the grain with a liquid culture syringe, or (a bit more risky due to contamination risks) a spore syringe, and let it myceliate. You can then mix the contents of both bags together in your monotub setup.
- Otherwise, you may have bought a kit, with pre-sterilized bags of grain and bulk substrate, the monotub, casing, etc. pretty much as in (B) but all the additional equipment and consumables are typically provided.
- Or, you may be working your way up from spores to agar to spawn, or maybe spores to PF-Tek, and ready to try your hand at a monotub.
Generally, you will want your bulk substrate to be 5 to 10 cm thick, with 20 cm to 30 cm for mushroom growth, leaving space for airflow above the mushrooms. A Minimum height of 30 cm would be best.
How to Make Monotubs
Part of the appeal to monotubs is that they are a fully enclosed fruiting environment; there is a certain element of set and forget, allowing the grower to check in at various points to ensure everything is going ok. There is also a lot of flexibility, with growers mixing their spawn with their chosen bulk substrate in the monotub, leaving it to myceliate, then casing (or not case!), then it becomes the fruiting chamber.
READ: Liquid Culture Guide: Everything You Need to Know About Mushroom Cultivation
Fungi are their own kingdom and more closely related to animals than plants; as a result, fungi like similar conditions as humans – they like warmth, and fresh air. So, while Monotubs may vaguely resemble terrariums as self-contained growing environments, a big difference is that fungi need airflow. Monotubs, therefore, typically have air holes for air exchange accompanied by filters either made of Tyvek or micropore tape that helps prevent contamination from airborne fungi and limiting insects such as fungus gnats while still allowing airflow. It used to be typical practice to use polyfill as filters till it was discovered that fungus gnats could squeeze their way between the polyfill fibers.
While there are various designs, the typical monotub has six holes, two holes on each long side, and a hole at each end. A variation on the typical design is to include a few extra holes on each long side placed just above the level of the substrate to allow airflow below the canopy of the mushrooms. The holes should be made with care, as the plastic in most tubs is brittle and can crack easily. Holes should be made using either a circular drill, a hot plastic blade to cut the plastic, or a heated tin can to melt through the plastic – care should be taken not to burn yourself or breathe in fumes.
Setting Up Your Grow
Key points: prepare your substrate, inoculate your substrate, incubate, introduce fruiting triggers
Regularly check on your spawn, whether it’s PF-Tek style cakes, a purchased spawn bag, or an inoculated kit. Once it’s fully myceliated, it will look white and fluffy, it is time to prepare your monotub. Before you can begin, you need to prepare your substrate.
If you bought a kit, a sterile bag of grain and a sterile bag of substrate, or a 2-in-1 bag where the two are combined, once the grain is fully myceliated, you empty the bag(s) into the prepared monotub. By pre-prepared, we mean lining the monotub with a large black plastic bag into which you place your spawn plus substrate, then pat down, and leave to myceliate, covering the substrate with the black plastic to minimize light. Light can be a fruiting trigger, and to control fruiting, it is best to minimize light till you are ready.
READ: How to use Agar in Mushroom Cultivation
If you have a bag of spawn, you will need to create your bulk substrate. The most common substrate people use is coco coir, pasteurized (cooked at 65-80 degrees Celsius or 149-176 degrees Fahrenheit) for an hour in water, then drained and squeezed until no water drips out — this is called field capacity. When cool, this can be mixed and placed in the plastic bag within the monotub. As above cover the substrate by folding over the plastic. There are numerous recipes for substrates that include variations on coco coir, straw, manure, and vermiculite.
While myceliating, cover all the holes with plain tape. The holes should not be breathable; this will minimize any moisture loss and allow CO2 to build up. The lids on most boxes do not fit well so will allow some air exchange during myceliation.
Once 100 percent myceliated, the substrate is ready for fruiting triggers. The tape is removed from the holes and replaced with micropore tape (or tyvek). Cut away the margins of the plastic bag to 1-2 cm above the substrate — this exposes the myceliated substrate to fresh air and light, both of which are fruiting triggers. This is also when you want to case the substrate with a layer of coco-coir.
Maintaining Your Monotub
Key points: humidity and moisture, temperature, and cleanliness.
A significant benefit of growing mushrooms using a monotub is that you can (mostly) set it up and forget about it for a while, as it is a self-sufficient environment. The mycelium has most of its moisture needs satisfied by the substrate, and the evaporation from the substrate helps maintain humidity.
You can upgrade your monotub somewhat by including a temperature and humidity sensor and tracking any changes. If your humidity is falling below 80 percent, it is advised to mist the sides of the monotub, or you can pipe in some humid air from an electric humidifier, or a humidibucket. Typically, you want humidity to be between 70-90 percent. If you live in a humid environment, this shouldn’t be a problem, but if your air is really dry, the humidity in the monotub may drop below 70 percent.
Other factors to keep in mind are that each species has its own environmental requirements, but all need a little airflow, some more than others.
Fresh Air Exchange (FAE) might be a factor for the species you are growing. Oyster mushrooms, for example, require a lot of Fresh Air Exchange (FAE), either lots of Fanning or a small 12v fan on a timer. Ganoderma require little FAE as they like humid environments with little air exchange, and cubensis sit somewhere in the middle where they appreciate some FAE, but the holes in the monotub allow enough air movement to satisfy their needs.
Maintaining Temperature may also be tricky. Fungi require temperatures between 59-64.4 to 95 degrees Fahrenheit (15-18 to 35 degrees Celsius). Fungi can survive in temperatures down to 32 degrees Fahrenheit (0 degrees Celsius), but their metabolism will decrease. Some people use horticultural or retile heating mats to maintain a constant temperature.
Lastly, keep an eye out for contamination. The appearance of green or blue spores is usually not a good sign for the fungi, or for you! Contaminated monotubs are best disposed of as soon as you find them. Ideally, dispose of the contents in a compost bin, yours or your community bin, or bag the substrate and dispose of it in a trash bin. Be careful not to breathe in spores.
Harvesting Your Mushrooms
One of the most commonly asked questions is when to harvest your mushrooms. This is dependent on the types of mushrooms you are growing in your monotub. Typically, it is best to pick mushrooms when they are mature and follow proper harvesting techniques according to the species.
Psilocybe species: Your mushroom is ready to harvest when the partial veil that protects the gills during development begins to tear or fall away from the cap, revealing the gills, and the cap fully opening. It is best to harvest before the cap fully turns upward.
Agaricus: This depends on how you want to consume the mushrooms. Either as button mushrooms, crimini, or as portobello – each name representing the mushroom at a different age, young, medium, or old. The best yield is when they are as portobello, but the margin of the cap is still rolled up
King Oyster: As the mushrooms grow, keep an eye on the margin of the cap. You will be able to see the caps gently unroll. King oyster cap are usually small as they are grown for their stem.
Harvesting is a little up to preference, but the common advice for most mushrooms is that the best time to harvest is just before the margin of the caps are fully unrolled. This is when they are commonly regarded as being at their best, but this is also up to personal preference — some people prefer them when they are smaller.
If your mushroom is part of a cluster, pick the whole cluster — pull gently from the base, twisting, to gently break the mycelium. Sometimes, there is a decision about when to harvest, as clusters can contain mushrooms that are not fully mature, so it may be best to let the larger ones mature a bit more so the small ones can grow more. There may also be a temptation to pick one or two from a cluster, but this usually stops growth, causing aborts (which are still ok to eat). Mushrooms are very sensitive to sudden changes in their microclimate and can stop growing if this change too much too quickly – such as rapid changes in temperature or humidity.
Once harvested, place the monotub somewhere dark, remove the micropore tape, and reseal the holes with ordinary tape. Leave for a couple of weeks to allow the mycelium to recover and build up a reserve of nutrients to allow a second and then a third flush.
If you have too many mushrooms, you can dry them. Drying is best done somewhere with warm air movement, such as in a dehydrator—the same kind used to dry fruit—or by leaving the mushrooms on a rack in a warm and dry part of the house. They need to be “cracker dry,” meaning they snap easily. With cubensis, you may want to vacuum pack them to limit air movement, then store them in a dark, dry location.
Once dry, store in a self-seal bag (or two, with one inside the other) with a satchel or two of desiccant in an airtight glass jar or plastic container in a cool, dark place. If not stored properly, they can absorb moisture and become moldy or attract mites and insects.
Conclusion
Montotubs are a practical and cost-efficient way to grow a variety of mushrooms. While monotubs don’t suit all types of fungi, the self-contained nature of this method makes them perfect for home growing and, given busy lives, allows for little ongoing maintenance. Keep your growing environment clean, keep an eye out for contamination, track your grows using a mushroom cultivation journal, and before you know it, you can be harvesting a variety of fresh homegrown fungi.
