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Monotub Substrate Refill – Manure & Millet


This Monotub substrate refill kit includes:

  • One 3lb. bag of Millet Grain
  • Three 5lb. bags of manure based substrate with gypsum, vermiculite, oyster shell and coco coir
  • One 5lb. Bag of coco coir for casing
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Need help choosing the right type of grain for spawn?

Read our article about choosing the best grain for mushroom spawn.

Inoculating a Mushroom Growing Kit injection port grain bag with a liquid culture syringe is a common method for growing mushrooms. The following is a brief description of the process:

  1. Start by sterilizing your work area, your hands, and all equipment you will be using. This will help prevent contamination.

  2. Shake the liquid culture syringe to distribute the mycelium evenly throughout the liquid.

  3. Locate the injection port on the grain bag. This is usually a small self-healing rubber port on the side of the bag.

  4. Wipe the injection port with an alcohol swab to sterilize it.

  5. Remove the cap from the syringe and insert the needle into the injection port at a slight angle. Be careful not to push the needle in too far, as this could damage the bag.

  6. Slowly depress the plunger on the syringe to inject the liquid culture into the bag. Try to distribute the culture evenly throughout the grain.

  7. Withdraw the needle and replace the cap on the syringe.

  8. Repeat this process with any other bags you want to inoculate. Be sure to sterilize the needle in between inoculating bags.

  9. Place the inoculated bags in a cool, dark place and wait for the mycelium to grow. If you have a still air box or flow hood, that would be optimal for minimizing contamination. Depending on the species of mushroom, colonization can take anywhere from a few days to a few weeks.

By following these steps, you should be able to successfully inoculate an injection port grain bag with a liquid culture syringe and begin growing your own mushrooms. For best results be sure your grain bag is fully colonized before transfer.

To cultivate a successful mycelium growth, it is crucial to provide an ideal environment for your bag. Find a cool and shaded area where the temperature ranges between 55 to 75 degrees Fahrenheit (depending on strain). Give the bag a few weeks to colonize and observe the emergence of mycelium on the grain.

As the mycelium grows from the injection point, it will gradually spread outwards, forming a white layer on the grain. Once the mycelium has extended three to four inches in length, it is time to carefully break up the colonized grain and blend it with the uncolonized grain. This will facilitate the colonization process and quicken its growth.

The colonization process can take a few weeks to a month or more, depending on the species and storage conditions. Keep an eye on the bag and watch for the complete white layer of mycelium to form, indicating that your spawn is ready to use. With patience and a good environment, you can produce a healthy and robust mycelium culture.

Once the grain bags are fully colonized, break up the mycelium and grain by massaging the bags. Open the bags and layer the inoculated grain and moistened subsrate in the monotub. Start with a layer of substrate, followed by a layer of moist coco coir, and continue alternating until all materials are used up. The top layer should be coco coir.

Place the lid on the monotub, ensuring the holes and filters are properly aligned. The filters will allow for proper air exchange, which is crucial for mushroom growth.

Move the monotub to a location with indirect sunlight or ambient room light, and maintain a temperature of 65-75°F (18-24°C) and a relative humidity of 80-95%. You can achieve the proper humidity by misting the inside of the tub with water and fanning for air exchange 2-3 times per day.

Within 7-14 days, you should start to see small mushroom pins forming. Continue misting and fanning as needed. Once the mushrooms have matured (usually when the veil under the cap begins to break), gently twist and pull them from the substrate to harvest.

After the first flush of mushrooms, you may get additional flushes. Allow the substrate to rest for a week, continue misting and fanning as before. You can expect 2-4 flushes of mushrooms before the substrate is exhausted.

Remember that growing mushrooms can be an art as much as a science. You may need to make adjustments to your process based on your specific environment and conditions. Don’t be discouraged if your first attempt isn’t perfect; practice and experimentation will lead to better results.

All of our injection port grain bags are sterilized and filled in a lab environment. We take great precautions to ensure your products are viable upon arrival. However, some contamination can occur with shipping damage.

When you receive any of our products, it’s best practice to set them aside for 4 to 7 days before using. Inspect the product regularly for signs of contamination and if you notice something, we’ve got you covered! 

All of our products come with our sterile guarantee. If something gets lost or damaged during shipping, we’ll replace it at our expense. Just contact us.

Monotub Substrate Refill Kit – a comprehensive set of components designed to facilitate the successful cultivation of mushrooms in a controlled environment. This kit offers an optimal balance of nutrients, moisture retention, and aeration, supporting vigorous mycelial growth and fruiting.

Included in the kit:

  1. One 3lb bag of sterilized millet grain – This sterilized millet grain, carefully selected for its nutrient content, provides an excellent substrate for mycelium colonization. The grain’s composition ensures an appropriate balance of essential nutrients required for the development of fungal species.
  2. Three 5lb bags of manure-based substrate – Each bag contains a carefully formulated blend of manure, gypsum, vermiculite, oyster shell, and coco coir. The blend offers an ideal combination of nutrients and moisture retention properties, promoting robust mycelial growth and an abundant harvest of mushrooms.
  3. One 5lb bag of additional coco coir – Specifically included for the creation of a casing layer, this high-quality coco coir aids in maintaining optimal humidity levels within the monotub. The casing layer is crucial for successful fruiting, as it prevents desiccation of the mycelium and fosters a more uniform and prolific flush of mushrooms.

The Monotub Substrate Refill Kit provides an all-inclusive solution for the replenishment and maintenance of a healthy environment for mushroom cultivation. This comprehensive bundle eliminates the need to source individual components, streamlining the process for both experienced cultivators and novices alike. With the Monotub Substrate Refill Kit, fungal enthusiasts can confidently support their mushroom-growing endeavors in a scientific and systematic manner.

Additional information

Weight 500 oz
Dimensions 17.25 × 13.25 × 13.25 in


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