The largest living organism in the world is a fungus - a Honey Fungus (Armillaria Ostoyae) found in Oregon. It covers more than two thousand acres and weighs over 30,000 tonnes. Most of this specimen - known as the “Humongous fungus” lives underground, as mycelium. 

Mycelium is a complex interwoven web of strands of cells that are the nutrient-absorbing sponge for the fungus. A square inch of mycelium can contain millions of miles of these strands. Trees are even known to communicate with each other using mycelial networks. 

Mycelium creates a thread-like structure that spreads through and colonises the grow bag substrate. It is from this network that mushrooms eventually sprout. So, the key to high mushroom yields and quality is dependent on the health of your mycelium. In this article, we want to walk you through the essentials - temperature, humidity, incubation time, and substrate - of how to achieve a healthy mycelium.

Temperature: Keeping Things Warm (But Not Too Warm)

Mycelium thrives within a specific temperature range - 21-26°C, depending on the type of mushroom. Temperatures outside of this range can slow down growth or even damage the mycelium. For most beginners, maintaining this consistent warmth can be a challenge, especially if you don’t have a controlled environment.

With the Mentis Toolbox, this aspect is simplified. The Toolbox acts as both an incubator and a grow kit, helping maintain the right temperature without the need for constant monitoring. By keeping the mycelium warm but stable, you’re setting up the foundation for a successful grow.

Humidity: Why Dampness Matters

Humidity is another key factor. Mycelium needs a humid environment to grow, ideally around 90% humidity during the incubation stage. High humidity provides the mycelium with the moisture it needs to absorb nutrients expand through the substrate.

The Mentis Grow Bags have a unique recipe that optimises for moisture content and therefore humidity. It has been designed so that you should not have to cut open your grow bag until you are ready to harvest your first mushrooms. Once the bag is open, we recommend misting inside the bag daily with 15-20 sprays. By keeping the bag closed during colonisation you also maintain a high CO2 level, which is optimal for mycelium growth.

Incubation Time: Being Patient

Incubation time, the period in which mycelium grows through and fully colonises the substrate, can vary quite a lot. We have experienced it taking anywhere from three to ten weeks for full colonisation from the time of injection of the spore syringe. 

This part of the process often requires patience, as mycelium grows at its own pace, influenced by the stability and quality of the conditions around it. With the Toolbox, we have optimised for temperature and humidity. Just let the mycelium do its work. We recommend breaking up the mycelium part way through its colonisation journey because this promotes the quicker growth of a stronger and healthier mycelial network.

Choosing the Right Substrate

The substrate you choose is just as important as temperature and humidity. Substrates act as a food source, providing nutrients and water to fuel mycelium growth. Importantly, it also acts as a moisture regulator. The right substrate will support optimal colonisation, with options like coco coir and vermiculite often recommended for their moisture-retaining and -releasing properties. 

The Mentis grow bags come with a specially formulated substrate, comprising a mix of rye grain, coco coir, vermiculite and gypsum. With most grow bags, you will need to perform a soak step between full mycelial colonisation and fruiting. At Mentis, we have designed a grow bag that does not require this step, simplifying the process further.

From Mycelium to Mushroom Time: The Final Steps

Once your substrate is fully colonised, you’re ready for the final stage - fruiting, or "to mushroom time." This transition can take an additional 2-3 weeks, depending on your setup. By providing a slight drop in temperature and a bit more airflow, you can encourage mushrooms to start sprouting from the mycelium.