How to make a Monotub

Mastering Monotubs: A Comprehensive Guide to Building Your Own

Monotubs have become the go-to solution for home cultivators aiming to grow mushrooms efficiently and cost-effectively. These setups offer a controlled environment that fosters optimal mycelium colonization and fruiting, resulting in impressive yields. While acquiring grain spawn and bulk substrate is a critical step, knowing how to construct a monotub properly is equally essential for success. In this guide, we’ll delve deep into the construction process, assuming you already have your grain spawn and bulk substrate ready to go.

Before we jump into the construction process, let’s briefly review what a monotub is and why it’s an excellent choice for mushroom cultivation. A monotub is essentially a large plastic container equipped with ventilation holes, designed to create an environment conducive to mushroom growth indoors. It consists of several key components:

1.Container: Typically, a large clear plastic storage tub with a lid. The size may vary based on your space and the scale of your operation.

2.Substrate: The pasteurised substrate in which the mushroom mycelium will grow and receive water. This commonly includes Coco coir, vermiculite, gypsum and calcium carbonate.

3.Spawn: The colonised grain spawn culture that you’ll introduce to the substrate to initiate growth.

4.Liner: The protective barrier between the substrate and the tub itself, helping to maintain a clean environment. Typically a bin bag thats opened, cut into a single sheet and laid inside the tub.

5.Filter patch: A breathable patch or tape that covers the holes allowing gas exchange whilst maintaining humidity and resisting contamination.

Now that we have a basic understanding, let’s dive into the step-by-step process of building a monotub assuming you have your grain spawn and bulk substrate ready.
Need grain spawn and bulk substrate? this is available in Gaia Mushrooms Store.
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Step 1: Choose the Right Container.

Select a sturdy clear plastic container with a lid to maintain humidity. Ensure it’s large enough to accommodate your substrate and fruiting. Gaia Mushrooms 6LB bulk substrate and 4LB Grain Spawn will fill one 60L tall sided tub or two 30L tall sided tubs at an ideal substrate depth of 3-5 inches.

Step 2: Drill Ventilation Holes.

Using a drill with a 2-inch hole bit, carefully drill 6 holes around the perimeter of the container. 2 evenly spaced on the long sides of the tub 5 inches from the bottom and 1 central towards the top on each of the short sides. These holes are crucial for maintaining proper gas exchange within the monotub, preventing the build-up of carbon dioxide.

Step 3: Prepare the Liner.

In a monotub, the liner serves as a protective barrier between the substrate and the tub itself, helping to maintain a clean environment and aiding in the harvesting process. To create one, you’d typically use a large, sturdy plastic bin bag cut down the sides and opened into a single sheet. Simply insert the bag into the tub and ensure it covers the entire inner surface, you trim off excess after filling and mixing the spawn and substrate. The liner makes it easier to remove the substrate after harvesting and helps prevent contamination.

Step 4: Adding your spawn and substrate.

To fill a monotub with bulk substrate and spawn, start by filling the bottom of the tub with your chosen substrate mixture, keep 10% substrate behind in the bag, we will use this as a pseudo-casing layer later. Break up your colonised grain spawn in the bag, cut the top corner of the bag to make a pour spout. Evenly spread your colonized spawn over the substrate. Gently mix the spawn into the substrate using a clean tool or your gloved hands, ensuring thorough distribution. Spread the mix evenly across the bottom of the lined tub so you have a consistent depth. Gently flatten down your substrate mix pressing into the edges of the tub against the liner. Sprinkle the remaining substrate evenly over your mix covering any exposed grains and gently press the pseudo casing flat. Trim the excess liner with a clean pair of scissors so its about level with the substrate.

Step 5: Add your filters.

Using micropore tape as a filter patch for monotubs involves covering holes in the tub with the tape to allow for gas exchange while resisting contaminants from entering. Cut pieces of micropore tape slightly larger than the holes and firmly apply them over each hole, ensuring a tight seal. This allows for proper gas exchange throughout colonisation and fruiting while maintaining humidity within the monotub.

Step 6: Set Up Fruiting Conditions:

Place the lid securely on the container and transfer it to a suitable fruiting environment out of direct sunlight. Maintain optimal conditions by monitoring temperature, humidity, and airflow. Aim for a constant temperature, ideally 24ºC, maintaining cleanliness in the space. 

Step 7: Monitor Growth and Harvest:

Over the next few weeks, monitor the tub regularly for signs of mycelial growth. Mycelium will appear as white, fluffy patches spreading throughout the substrate. Allow the mycelium to fully colonize the substrate, which may take anywhere from 2 to 4 weeks depending on the species and conditions. Once the substrate is fully colonized, give it some additional time for consolidation. This helps ensure that the mycelium has fully permeated the substrate and is ready for fruiting. As the mycelium matures, mushrooms will begin to emerge, first appearing as tiny white balls called Primodia which will eventually become pins. At this stage, they become visibly distinguishable, resembling tiny protrusions on the surface of the substrate. Monitor closely over the next several days as the mushrooms grow at an astonishing rate, your hard work has paid off and you’re the proud owner of a mushroom family. Harvest mushrooms by gently pinching at the base of the stem, twisting and pulling upwards. The ideal time to harvest is just before the thin veil between the cap and the stem splits.

Building a monotub is a rewarding and straightforward process, especially when you have your grain spawn and bulk substrate ready to go. By following these steps and paying attention to detail, you can create an ideal environment for mushroom cultivation and enjoy a bountiful harvest. With patience and practice, you’ll soon be growing spectacular mushrooms in your own home. Gaia Mushrooms is an online store catering to beginners and advanced mycologists alike. Consider them for your journey in mycology, they offer top quality substrates at great value prices.

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