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How to Grow Mushrooms Using the Monotub Method

How to Grow Mushrooms Using the Monotub Method

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Here on the Growing Organic farm, we have a dedication to eco-conscious self-sufficiency. Several years ago, we made a commitment to transform our home into a homestead by adopting sustainable growing practices and incorporating the principles of permaculture to reduce waste. We have thoroughly enjoyed learning to grow a variety of fruits, vegetables, and herbs, as well as raising chickens for fresh eggs.

Since transitioning into a more holistic lifestyle, we have also begun to grow a variety of plants for their therapeutic benefits. Cannabis is the most popular such crop, but medicinal mushrooms are a vital part of our homestead, as well. We have recently shared a number of blogs that explain the benefits of several different strains of medicinal mushrooms, including our most recent post, which details how to grow your own medicinal mushrooms at home!

If you are not interested in growing your own mushrooms at home, we understand! Though much less time-consuming than foraging for wild mushrooms, growing your own medicinal mushrooms still may not be the project for you, and that’s okay! We are proud to offer a variety of medicinal mushroom tinctures in our shop. These tinctures may be helpful if you want to experiment with different varieties of mushrooms before choosing which kind to grow if you want to try blends of numerous mushrooms besides those you choose to grow, or if you don’t want to grow your own mushrooms at all.

This blog post aims to help our friends who have expressed a desire to begin growing their own medicinal mushrooms at home to do so in the most efficient way, by using the monotub method. We hope to simplify this process so that anyone can feel comfortable and successful in their mushroom-growing endeavors, but if you have any questions or useful tips that you think we should include, please let us know!

How to Grow Medicinal Mushrooms at Home Using the Monotub Method

Cultivation Overview

The monotub method is not a new technique. On the contrary, many (if not most) professional indoor mushroom cultivators actually begin by using this method. The benefits of a monotub setup are many, but it’s valued primarily for its relative simplicity for newcomers, and minimal space and equipment requirements. The monotub method is designed to utilize easily accessible components, allowing anyone to begin cultivating their own mushrooms at home.

The monotub technique is most frequently considered for varieties of mushrooms that thrive in manure, including psilocybe species. However, by switching out your substrate, you can also use this method to grow other varieties of mushrooms that thrive on wood mediums. A monotub setup is ideal for a wide range of mushroom species and is widely considered the simplest and most affordable choice, especially for beginners.

Cultivation Considerations

Type of mushrooms

Mushrooms are curious organisms. Surprisingly, mushrooms actually have much in common with animals and are often thought of as a hybrid creature: neither plant nor animal, but sharing characteristics with both. Growing mushrooms at home is not a terribly difficult process, but it does require an understanding of the mushroom’s biology, including not just how mushrooms grow, but when and why they thrive in certain conditions. More often than not, these details will be dependent upon the particular species of mushroom that you intend to grow, so a good first step is to make that determination. Check out our How To Grow Mushrooms post for a thorough explanation of the mushroom’s life cycle.

Preferred Growing Medium

One of the ways that growing mushrooms differ from growing herbs, fruits, or vegetables is in its preferred growing medium. Though you have likely discovered varieties of mushrooms growing in soil, perhaps even in your own backyard, growing a full crop of mushrooms on purpose often involves cultivating a manure or wood medium, such as a cut log or a bucket or container of sawdust or manure substrate. Different varieties of mushrooms will thrive on different mediums.

Importance of Sterile Technique

Whatever method you choose, it is vital to remember the importance of working in as clean an environment as you possibly can. Microscopic contaminants are every mushroom cultivator’s biggest enemy, as these various bacteria and molds can and will overtake your mycelium, destroying your entire cultivation. This does not mean that you should expect to eliminate 100% of contaminants, as that would be an impossible goal. But we can not overstate the importance of sanitizing not just your workspace, but ALL tools, including yourself.

We recommend you begin by practicing good personal hygiene. Take a shower or bath, brush your teeth, and put on freshly laundered clothing. Vacuum all floors, and disinfect and sanitize all surfaces. Immediately before and after use, we like to use 70% isopropyl alcohol to sterilize all of our worksurfaces, tools, and containers. Additionally, 3% hydrogen peroxide (H2O2) can also be a useful tool in sterilizing.

Also, remember to thoroughly wash your hands and wear latex or nitrile laboratory or surgeon’s gloves. For people who would prefer to cover the length of their forearms, agricultural insemination gloves are another popular and affordable option. Finally, put on a face mask to protect yourself from inhaling dust, and to protect the mushroom growing environment from your own exhalation particles.

Light direction for mushroom primordia

When setting up your monotub, think about the direction of any light that enters the room. While mushrooms do not use light for photosynthesis as plants do, some mushroom species use light to direct growth. For these species, when the mushroom primordia begin pinning, you will notice that the pins will grow towards the direction of the source of light.

How to Set Up A Monotub

Supplies Needed for One Monotub

  • Mushroom Spores, Cultures on Agar or Liquid Culture (not necessary if purchasing pre-inoculated grain spawn)
  • Sterilized Grain Spawn (either pre-inoculated or with an injection port)
  • Bulk Sterile Substrate (manure or wood)
  • Large Tub for Cultivating Mushrooms (or you can make your own using a large Tupperware, contractor bag as a liner, and drilling holes in the lid for airflow)
  • Microspore tape
  • 70% Isopropyl Alcohol
  • Two Spray Bottles
  • Latex Gloves (or equivalent material medical-grade gloves) & Dust Mask

Optional additional supplies:

  • Flowhood
  • Fan for airflow
  • Painters tape or similar, to secure filter disc or micropore tape
  • Cycle Timer
  • Humidifier & Humidity Regulator
    • Maintenance of ideal ambient humidity can greatly improve the success of your cultivation. We recommend setting up a humidifier with a flexible hose to direct towards your monotub, as well as a humidity regulator (humidistat) to ensure your ambient humidity level remains constant. Ink Bird is popular for this.
  • LED Light Bar
    • An LED light bar can be a wonderfully efficient and convenient option to bring light into your workspace. An LED light bar is especially well-suited to a monotub setup, because it does not emit heat and will not raise temperatures, and you can place it directly above your tub to encourage proper pinning (for mushroom species that grow towards light).

How to Prepare Your Monotub for Fruiting Mushrooms

Before we start fruiting mushrooms, there are a few preparatory steps that must be taken to ensure a successful mushroom grow.

sterilized grain bag with injection port for growing mushrooms at homePrep Step One: Spores or Cultures

Prior to beginning any method of mushroom cultivation, your very first step will be to acquire spores (or cultures), which you will use to inoculate and colonize grain spawn. Alternatively, you can choose to purchase pre-inoculated grain spawn, in which case you can move on to “Step Three: Purchase or Prepare Bulk Substrate”.

When buying mushroom spores for home cultivation, it is vital to make sure that you are purchasing from a reputable retailer. If your spores are contaminated before you begin, it will be impossible to run a successful cultivation no matter what else you do right.

Reputable retailers will guarantee their product for a length of time from purchase, typically around thirty days. When you receive your package of spore or liquid culture syringes, spore prints, or pre-inoculated spawn, you should inspect the package to ensure it is free from contamination. If you observe any signs of damage or contamination, contact the retailer to receive a replacement.

When first starting out inoculating your own spawn, you should expect to make mistakes. This means you should order more spores than you think you will need so that you increase your chances of success. Everyone messes up at least a few syringes on their first couple cultivations, so give yourself some room for error. Having more spores than you need will ensure that you can afford at least a few mistakes.

Bear in mind that laws regarding the legality of certain mushroom species vary across states and regions, with some species in certain areas only considered legal for microscopy research, not cultivation. Check local laws carefully before deciding which spores or culture to purchase.

sterilized grain bag with injection port for growing mushrooms at homePrep Step Two: Fully Colonize your Grain Spawn

You can choose to either purchase grain spawn that has already been inoculated and fully colonized (in which case you do not need to purchase spores or cultures), or you can inoculate and colonize your own spawn. The simplest way to colonize your own spawn is by injecting mushroom spores or culture into an Injection Port Bag, which is a bag of sterilized grain equipped with a self-healing port that you inoculate using a spore syringe. Once inoculated with spores, your grain spawn will need to fully colonize before it can be added to the sterile substrate (cultivation medium) in your monotub.

Instructions for Inoculating Grain Spawn using an Injection Bag

PREP STEP 2a: Inspect Materials / Sterilize Workspace / Inoculate Spawn

If you choose to inoculate sterile grain spawn using an injection syringe, you will want to follow the directions that come with your bag. As always, sterile technique is critical for success with these applications, so inspect any bags, syringes, or other materials carefully before use to check for signs of damage or contamination. Wipe down all surfaces, including the bag, syringe, and gloves with 70% isopropyl alcohol.

mushroom grain bag being injectedMany mushroom cultivators advise allowing any bags or other purchased materials to sit for one or two weeks prior to use. This allows time for any contaminants to generate mold, which should become visible during your inspection. If you have received a contaminated or damaged product, contact the manufacturer for a replacement before moving on.

If you are just starting out, we recommend purchasing your spawn. When first beginning, you may even want to purchase fully colonized grain spawn to simplify your cultivation process while you become comfortable with the rest of the monotub setup technique. But if you want to grow mushrooms that are less readily available in fully colonized spawn, you will eventually need to learn to make and colonize your own grain spawn. For this process, Shroomology provides an excellent guide to making your own grain spawn, using easily acquired ingredients such as wild bird seed and mason jars.

PREP STEP 2b: Wait for Colonization

If you are inoculating your own spawn, after introducing the spores or culture, you will need to leave the bag or jar undisturbed for a couple of weeks to become colonized. Colonization happens best away from direct sunlight, in a cooler location, between 55-75 degrees Fahrenheit. You will know your spawn is starting to become colonized when you see mycelium beginning to cover the grain.

Once the mycelium has spread three or four inches across, without opening or damaging the bag, carefully break up the mycelium-covered grain using your fingers and mix it throughout the rest of the uncolonized grain. This will spread the mycelium and speed up the colonization process. After a few more weeks, you should see the contents of the bag (or jar) are fully covered with fluffy white mycelium, meaning the colonization step is complete.

After you have made (or purchased) your fully-inoculated grain spawn, it will need to be mixed with the sterile substrate in your monotub. That means that sometime after inoculation, while your spawn is colonizing (or while you are waiting to receive your fully colonized spawn), you will need to prepare the rest of your monotub setup and bulk sterile substrate.

bulk substrate for mushroom growingPrep Step Three: Purchase or Prepare Bulk Substrate

Depending upon the species of mushroom you plan to cultivate, you will need either wood chips or manure-based growing substrate in your monotub. In the beginning, we recommend purchasing bulk sterile substrate, at least until you feel comfortable with the rest of the monotub setup technique.

If you are planning to cultivate a manure-loving species of mushroom, the Boom’r Bag is a great option that will save you the hassle of sterilizing your own manure. For mushrooms that prefer wood, you’ll need to sterilize your own wood chips or mulch. You could also choose to innoculate logs in the garden instead of growing them indoors.

When you’re ready, if you would like a bit more of a challenge and if it fits your application, you can choose to make your own manure-based bulk sterile substrate at home. Our friends at North Spore have provided a relatively simple method for making your own manure-based bulk sterile substrate from horse manure and coco coir, which we have included at the end of this article. Making your own spawn and substrate can be quite cost-effective in the long run, especially as you start to cultivate more mushrooms, but if you are just starting out it may be less frustrating to stick to purchasing prepared spawn and/or sterile substrate.

Fruiting Mushrooms Using The Monotub Technique:

Alright, now with a fully colonized grain spawn bag and sterilized substrate ready to go, it is time to fruit your mushrooms using the monotub method.

monotub system for mushroom growingSTEP ONE – Purchase your tub

We recommend purchasing a tub already made for cultivating mushrooms like the MaxYield Bins, or you can choose to buy a large plastic tub similar to styles made by Tupperware or Sterilite.

If you choose to make your own, you will need to line the tub and create holes for airflow.

If you purchase your mushroom cultivation bin from us, the tub is already blacked out and has pre-cut holes for airflow, so you can skip to step 4 where you will cover the holes with micropore tape or filterdiscs.

STEP TWO – Line your tub

*This step is only for those making their own monotub!

Older directions for the monotub technique frequently instruct cultivators to use black spray paint to cover the bottom of their tubs (if using a clear or transparent tub). However, over time our friends at North Spore discovered that this step – which was typically done to block light and prevent side-pinning, was not the best method. Instead, they recommend lining your tub with an opaque black contractor-type trash bag, but folded so that it only comes about half-way up the sides of the tub. This is the best method for discouraging pinning to the sides of the tub.

STEP THREE – Create holes in a tub for airflow

*This step is only for those making their own tub!

You need to make sure that your tub has air circulation, so drill holes around the outside of the tub using your hand drill fitted with a two-inch hole saw. You want at least one hole on each side of your tub, with no more than about eight inches between holes. Drill your holes just above where the top of your bulk substrate and liner will sit, or just above halfway up the sides of the tub.

STEP FOUR – Cover holes with micropore tape to prevent contamination

Use the micropore tape to cover the holes in the sides of your tub. This will protect the content of the tub from contamination while still allowing for adequate airflow. If desired, you can secure the micropore tape by placing painter’s tape around the edges of the holes on the outside of the tub. Just make sure not to cover your holes completely, as this will impede airflow.

STEP FIVE – Sanitize all materials

Next, it is imperative that you sanitize all of your work surfaces, including the entire monotub, liner, lid, and any tools. For sanitization of all surfaces and tools, we use 70% isopropyl alcohol. For proper sanitization, it is important not to use alcohol with a higher percentage than 70. Even though 90 and 99 percent isopropyl alcohol is widely available, the reduced water content of these formulations means that the alcohol evaporates much more quickly from treated surfaces, which does not allow sufficient contact time for effective sanitization.

Fill one of your spray bottles with alcohol and the other with freshly sanitized water. Alcohol may degrade plastics and other materials over time, so it may be worthwhile to invest in an industrial-grade, chemical-safe spray bottle for the alcohol. Spray down both the inside and outside of your tub, all working surfaces and tools, and your own gloves. Make sure not to forget to sanitize the entirety of the outside of all spawn and substrate bags, along with any scissors you use to cut them open! Make sure the room where you’re working has been vacuumed recently (but not too recently, as the air turbulence created by vacuuming can introduce contaminants). Close all doors and windows, and take care to keep any pets, children, or visitors out of your sterile environment.

STEP SIX

Get excited…It is finally time to add your bulk sterile substrate to your monotub, and begin inoculating it with your fully colonized spawn!

After sterilization, cut open your bag of bulk substrate and fill your monotub evenly so that the substrate is about one inch deep throughout the tub to start. Make sure that your substrate is at “field capacity”, meaning that if you squeeze a clump in your fist, you should only be able to get out a drop or two of water. If your substrate is too dry, add a small amount of sterilized water to the mix when you add it to the tub.

Follow by sprinkling a thin layer of fully colonized spawn over the base of sterile substrate. Then add another inch of substrate, and top with another thin layer of spawn. Keep repeating this process until you have reached the desired substrate depth, usually around three to five inches deep throughout the tub.

The amount of bulk substrate and spawn you will need will be dependent upon the size of your tub, but generally, one three-pound bag of spawn can be expected to colonize one or two monotubs, when combined with ten pounds of sterilized substrate.

STEP SEVEN – The “Spawn Run”

For extra protection against contaminants, spray a paper towel with alcohol and wipe down the inside of your monotub above the liner and substrate. Wipe down the lid (or a second tub turned upside down) and cover the monotub.

Leave the monotub undisturbed in a warm (but not hot) environment, away from direct sunlight but not in total darkness – inoculation will happen faster with moderate exposure to ambient light. Aim for a room temperature of 77-80 degrees Fahrenheit, and do not disturb or check on the monotub contents for any reason whatsoever for at least six to ten full days, as doing so will allow carbon dioxide to escape the tub, increasing colonization time, and potentially introducing contaminants. The only reason to open the tub during this time is if you smell a very rancid or foul odor coming from the monotub.

After this initial period, you should begin checking the tub once daily, expecting to see white spots of mycelium extending out from each piece of grain spawn. Eventually, these spots will expand and connect to take over the entire surface of the bulk substrate, and you may see small droplets of mushroom exudate, which is a sign of proper hydration and successful colonization.

Manure-based substrate species will take two to three weeks for the mycelium to “run” (or colonize) the entirety of the substrate, while grain- and wood-based substrate times will vary. Around this time, you should begin looking for the formation of hyphae – this is what is called mushroom “pinning”, and will look like dense knots of white mycelium extending vertically from the surface of the substrate. Hyphae knots or “pins” are the sign that your substrate is fully colonized, and it is time to move on to casing your monotub.

STEP EIGHT – Casing, Fruiting & Harvesting your Monotub

Once you begin seeing the formation of primordia, you have the option to case your tub, which means covering the entirety of the substrate with a very thin layer of 100% coco coir. However, this step is completely optional. Additionally, you can also remove the lid from your tub at this time.

Add a one-half inch to one-inch thick layer of 100% coco coir to your tub, and then spray the layer with sanitized water until the coco coir appears fully hydrated.

Some mushroom cultivators use vermiculite instead of coco coir for casing, but recent research has shown a connection between vermiculite casing and asbestos contamination, so we highly recommend avoiding vermiculite in favor of coco coir.

Check the monotub daily, leaving the lid slightly offset on the tub, allowing for increased oxygen flow and reduced CO2 within the tub. Spray the top layer of casing, sidewalls, and lid of monotub with sanitized water one to three times daily. About 7-14 days after casing, you should begin to notice hyphae poking up through the casing layer. Make sure to allow minimal to moderate light to reach the tub to encourage these pins to grow in the proper direction, but do not expose the tub to excess light or heat.

Eventually, you will notice your hyphae pins will begin fruiting or turning into mushrooms that are ready for harvest. You can harvest your mushrooms according to your own preferences, but for most edible capped species, the best time to harvest will be just before the mushroom caps have flattened.

Fruiting only happens if a few environmental conditions are present. The temperature of the tub should remain between 68-72 degrees Fahrenheit for the best quality mushroom formation. Additionally, it is imperative that you check your monotub daily and maintain hydration, as decreased CO2 and moisture evaporation from the surface of the substrate are key to fruiting conditions.

Harvesting Mushrooms & Spore Printing

As mushrooms mature, they will begin to drop spores from their caps (for capped species). Mushroom caps have a veil underneath the cap, which breaks to release these spores, propagating the next generation of mushrooms. Most cultivators prefer to harvest their mushrooms immediately before or after the veil breaks.

To cause the least damage while harvesting your mushrooms, grab each one by the base of its stem and gently but firmly twist each direction until you feel it separate from the substrate and casing. Do not just rip out your mushrooms. Bring a flat receptacle to place the mushrooms upon, such as a clean plate or lid.

If you want to preserve a specific mushroom strain for future cultivation, you can “print” its spores after harvesting, and then use these spores to cultivate more mushrooms of the same strain in the future. Spore prints can also be used to help identify mushroom species, or sprayed with a fixative and displayed for their artistic value. If planning to use for cultivation, it is critical to maintaining sterile procedure while making spore prints in order to avoid contamination.

Making Spore Prints

To make spore prints, begin by fully sanitizing your entire work area, including any tools and yourself. Place a freshly picked mushroom cap (stem removed with a sterile blade) gills-down onto a piece of black or white paper, stiff plastic, or aluminum foil. (Aluminum foil is often preferred by cultivators, as it is inexpensive and can be sanitized with alcohol.)

Place something over the top of the mushroom cap to protect it from disturbance and contamination – sanitized cups and bowls work well. Leave the cap for six to twelve hours, then carefully remove the cover and the mushroom cap from the foil (or paper). Place the cover back over the new spore print for another six to twelve hours to allow it to dry completely.

Once the spore print is dry, remove the cover and carefully make an envelope out of the foil to protect the print. This can be done by folding up the bottom half of the foil, then folding in each of the sides to make a seal around the edges. Make sure to double-fold the edges of your envelope, and to make clean, crisp folds to prevent any mites from accessing the spores inside. These envelopes are best stored inside self-sealing bags with oxygen- and moisture-absorbing packets to prevent degradation. Even so, if hoping for successful cultivation, spore prints should be used within a year or two, at most.

Through our blog posts, we hope to encourage you to explore the wide variety of mushrooms that can be grown at home, including not only the many species that are prized for their culinary value but also those that have historically been associated with increased health and wellness. If you have questions about a specific species of mushroom or aspect of this technique, please send us a message.

*Growing Organic asks that you familiarize yourself with your local laws regarding mushroom cultivation. We do not condone, support, or encourage any unlawful activity. *

Making Your Own Manure-based Sterile Substrate

Directions from North Spore at https://northspore.com/pages/mono-tub-cultivation-method-walkthrough

Instead of purchasing bulk sterile substrate, you can make your own manure-based bulk sterile substrate at home. For this, you will need the following additional supplies:

  • Coco coir (sold at hydroponic or urban gardening grow shops)
  • Horse manure (best manure is composted at least six months)
  • OVEN METHOD:
    • baking pan
    • aluminum foil
  • STEAM METHOD
    • filter patch bags
    • pressure cooker (optional)

This recipe is for making bulk sterile substrate for mushrooms that thrive on a manure-based growing medium. For grain- or wood-loving species, you will need to use sterilized grain or hardwood chips, such as oak or maple.

The easiest recipe for making your own manure-based bulk sterile substrate is to combine 50% coco coir with 50% horse manure. Quality horse manure can be sourced from farms that board horses or offer riding lessons. For best outcomes, manure should be composted at least six months prior to use.

First, mix the coco coir and manure to “field capacity”, meaning when you squeeze a handful of the substrate as hard as possible, only one or two drops of moisture come out. If the mixture is too dry, add tiny amounts of water, testing frequently until the proper hydration level is reached. If the mixture is over-hydrated, add more coco coir until field capacity is achieved.

Next, the manure will need to be pasteurized either by cooking in an oven or steaming. If you wish to use the oven method, preheat your oven to 170 degrees Fahrenheit, then place the substrate onto baking pans and cover with aluminum foil. Once preheated, cook the covered substrate in the oven for at least two and a half hours.

If you would rather use the steam method of pasteurization, load the substrate into filter patch bags. Cook the bags in a pressure cooker or steam on the stovetop until it reaches 160-180 degrees Fahrenheit.

Allow the pasteurized substrate to cool completely before handling.

We hope you’ve found this helpful in your mycology journey. As always, don’t hesitate to ask any questions below in the comments and we will do our best to help you. We want everyone to enjoy the fruits mother nature has to offer us.

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