Mushroom Colonization: A Step-By-Step Guide To Success

Mushroom cultivation is an exciting and rewarding process, but it requires patience and attention to detail. The colonization phase, in particular, is critical to the success of mushroom growth. Colonization refers to the period when mushroom spores grow and expand, forming a mycelial network that eventually produces mushroom fruits. This phase typically takes 7 to 30 days, depending on various factors such as the mushroom species, environmental conditions, and cultivation practices. Before beginning the colonization process, it is crucial to determine the preferred growing method and the type of mushroom you want to cultivate. Additionally, sterilization and contamination prevention are key aspects of successful mushroom colonization.

Choosing a growing method and mushroom type

For beginners, it is recommended to start with faster-growing mushroom species, such as oyster mushrooms, which can colonize in as little as 7-14 days. Other mushroom types that are commonly cultivated include shiitake, lion's mane, and various hybrids used in the United States, including smooth white, off-white, and brown mushrooms.

Once the mushroom type is selected, the growing method can be determined. There are several options available, each with its own advantages and disadvantages. Low-tech methods, such as using straw or logs, are suitable for oyster mushrooms and shiitake mushrooms, respectively. These methods are generally slower but require fewer resources. On the other hand, higher-tech methods utilize sterilization techniques and nutrient-rich materials to increase the speed of colonization and yield. Examples of high-tech methods include the use of sawdust, hardwood fuel pellets, and nitrogen supplements.

Additionally, there are specific growing methods designed for different levels of convenience and expertise. The All-in-One-Bag method is a popular option for beginners as it is user-friendly and contamination-resistant. It allows for fruiting directly in the bag or by cutting off the top. Another method is the Mono-tub/Dub-tub method, which involves breaking up the colonized grain, mixing it with the fruiting substrate, and then introducing it to fruiting conditions.

Furthermore, the ShroomTek method provides an all-in-one solution for growing mushrooms in bags, reducing the hassle of mixing substrates and sterilization. It offers a controlled environment with minimal maintenance, making it suitable for beginners. For those seeking a more advanced approach, the use of specialized facilities and techniques, such as pasteurization and Phase III and Phase IV composting, can enhance the quality and quantity of mushroom crops.

Preparing the substrate

There are various materials that can be used as substrates, each with its own advantages and suitability for different mushroom species. Straw, for example, is a popular choice as it is inexpensive and effective. It can be purchased at farm stores or places that sell animal feed or bedding. Coffee grounds are another good option as the brewing process pasteurizes them, reducing the preparation steps. They are also easy to obtain for free from local coffee shops. Wood logs are often used for growing shiitake mushrooms and other varieties outdoors. When using wood-based substrates, it is best to inoculate them within a month of cutting, as it takes time for native fungi to get established.

The preparation process will depend on the chosen substrate. For straw, some people use chemicals like peroxide or calcium hydroxide, while others prefer to ferment the straw for a week or more. A heating method can also be used, which is both quick and organic. This involves cutting the straw into three to four-inch pieces. For coffee grounds, simply blend a kilogram of grounds with 100 grams of mushroom spawn. You can add 20% straw to this mixture for improved air exchange and faster colonization.

Regardless of the substrate chosen, there are some general guidelines to follow. The substrate should be slightly acidic, with a pH between 5 and 6.5. It should also have a moisture content of at least 50-70% and a nitrogen content of 1-2%. It is important to ensure that the substrate is damp but not wet. Contamination is a common issue, so it is crucial to sterilize the substrate properly and maintain a clean and sterile work environment. Always allow the substrate to cool completely before inoculation to avoid cooking the mycelium.

The choice of substrate depends on the species of mushrooms being grown. Wood-based substrates are optimal for certain mushrooms like reishi, lion's mane, and maitake, while oysters can grow on almost any substrate. It is important to match the substrate to the mushroom species and consider factors such as availability and ease of preparation.

Sterilization and inoculation

To sterilize the substrate, choose a suitable sterilization technique such as pressure cooking or pasteurization. When using a pressure cooker, ensure the substrate is properly sealed in containers with tight-fitting lids. Place the containers in the pressure cooker with water, following the manufacturer's instructions for secure closure. After sterilization, carefully remove the containers and allow them to cool to room temperature.

For pasteurization, you can hydrate the fruiting medium and cook the hydrated substrate at 180°F for 1-2 hours. Then, remove it from the heat, let it cool, and proceed with inoculation. Natural substrates like wood logs can be pasteurized by inoculating them outdoors, as the natural environment provides a form of pasteurization.

Inoculation is the process of introducing mushroom spores or spawn to the sterilized substrate. It is essential to maintain a clean and sterile environment during inoculation to prevent contamination. You can purchase microscopy spore syringes or liquid cultures for inoculation. When using a syringe, ensure the needle is flame-treated or sterilized before penetrating the substrate. If you're using a scalpel, flame-treat it after each use.

For liquid cultures, you can prepare a mixture of ingredients such as honey, light malt extract, or Karo syrup with distilled or deionized water. After inoculation, monitor the substrate daily for any signs of contamination and maintain optimal environmental conditions, such as temperature and humidity, to promote healthy mycelium growth.

Incubation and colonization

Incubation

Incubation is the period when the mycelium colonizes the substrate or growing medium. During this phase, the mycelium, which is the vegetative part of the fungus, forms a network of fine, white threads called hyphae. This network is essential for mushroom growth and has various industrial applications. The incubation period can vary depending on the mushroom species and environmental conditions. For example, shiitake mushrooms may require an incubation period of about a year, while oyster mushrooms can colonize a substrate within a few weeks under optimal conditions.

To promote incubation and mycelium growth, several factors must be considered:

• Suitable Substrate: Choose a substrate that is compatible with the mushroom species. Popular options include straw, wood chips, coffee grounds, or grain spawn.
• Pasteurization or Sterilization: Eliminate unwanted microorganisms that can hinder mycelium growth through pasteurization or sterilization processes.
• Mixing the Substrate with Mycelium: Ensure thorough mixing of the substrate and mycelium for even colonization.
• Environmental Conditions: Maintain a dark, warm, and humid environment. Ideal temperatures range from 20-25°C (65-75°F) with high humidity levels of 85-100%. Keep the incubation area well-ventilated to promote growth and prevent contamination.
• Moisture: Regularly spray the substrate with water to keep it moist, as moisture is crucial for mushroom development.

Colonization

Colonization is the process by which the mycelium grows and expands, forming a mycelial network. This network is the actual fungal organism that later produces mushroom fruits. The colonization timeline can vary depending on the mushroom species, environmental conditions, and cultivation practices. Oyster mushrooms, for instance, can colonize in as little as 7-14 days, while Lion's Mane may take up to 21-30 days.

To ensure successful colonization:

• Monitor Conditions: Regularly check temperature, humidity, and mycelium growth. Adjust conditions as needed to optimize colonization speed and consistency.
• Substrate Preparation: Properly prepare the substrate by mixing it with the mycelium and ensuring it is free from contamination.
• Inoculation Techniques: Introduce spores to the substrate using spore syringes or liquid cultures. Ensure the inoculum is evenly distributed within the substrate.
• Sterile Practices: Maintain sterile practices to prevent contamination. Use clean equipment and work in a sterile environment, especially when working with high-nitrogen substrates like grain.
• Fresh Spawn and Nutrient-Rich Substrates: Using fresh spawn and nutrient-rich substrates can accelerate colonization.
• Environmental Triggers: Once the substrate is fully colonized, provide the proper environmental triggers to initiate mushroom formation. These triggers include fresh air, humidity, light, and temperature changes.

Fruiting and harvesting

Once the substrate is fully colonized, the mycelium forms a thick mat, and it's time to initiate the fruiting process. Move the substrate to an area with over 90% humidity and temperatures between 55°F and 80°F to encourage growth.

For the first few days, open the fruiting container and spray the block with water using a hand mister. Mist each side of the block to prevent it from drying out. In a few days, you'll see mushroom pins (baby mushrooms). Keep misting the blocks each day until the mushroom pins start to look like proper mushrooms. If you continue misting at this stage, they tend to stay wet and have a reduced shelf life after harvesting.

Mushrooms first appear as pins, growing into stems and caps. When the cap inverts and edges wave, they're ready for harvesting. Each flush lasts 3-5 days, and with ideal conditions, harvesting can continue for weeks or even months.

Harvesting mushrooms is a labor-intensive process. Stabilize each stalk with one hand and gently twist it off the base to preserve the developing mycelium. You can also use a knife or scissors. Be sure to remove all of the fruiting bodies remaining on the block down to the myceliated substrate to prepare for a second fruiting and prevent rotting and possible contamination.

Once harvested, mushrooms can be used fresh, refrigerated, packaged, dried, or even pickled for extended shelf life. After harvesting, the growth medium can be composted, and the cycle can begin anew.

Frequently asked questions