Fresh Mushrooms: Sawdust Secrets For Success

Growing mushrooms on sawdust is a popular method among enthusiasts and commercial growers. It is a practical, cost-effective, and widely accessible approach that taps into the natural decomposition process mushrooms thrive on. To ensure a constant supply of fresh mushrooms, it is essential to maintain optimal growing conditions and properly care for your crop. This includes regular monitoring for moisture loss, contamination, and other issues, as well as humidity control and adequate air circulation to prevent carbon dioxide buildup. Proper sterilization of the sawdust substrate and equipment is crucial to prevent contamination, and overwatering should be avoided. With the right techniques, you can cultivate a thriving mushroom garden and enjoy fresh, delicious mushrooms with extended shelf life through proper storage methods.

The benefits of growing mushrooms on sawdust

Growing mushrooms on sawdust is a popular method among mushroom enthusiasts and commercial growers. This approach harnesses the natural decomposition process that mushrooms thrive on, using sawdust as a cost-effective and widely available substrate. Here are some key benefits of growing mushrooms on sawdust:

Versatility and Ease of Use

Sawdust is a versatile and straightforward growing medium. It can be easily sourced from local factories, sawmills, or woodworking processes, making it readily available to growers. Additionally, the sawdust method allows for customization with supplements, such as wheat bran or nitrogen-rich additives, to enhance mushroom growth and nutrition. This versatility makes it suitable for both beginners and experienced cultivators.

Quick and Consistent Harvests

Growing mushrooms on sawdust blocks is known for producing quick and consistent harvests. It is one of the fastest methods for obtaining fresh mushrooms and is used by many commercial growers for this reason. Sawdust blocks provide larger yields than other substrates when supplemented properly.

Space Efficiency

Mushrooms grown on sawdust blocks do not require a lot of space. They can be stacked vertically, making them suitable for indoor growing all year round. This space efficiency is especially advantageous for those with limited growing areas or for commercial growers aiming to maximize their crop yield in a confined space.

Low Contamination Risk

The sawdust method has a lower risk of contamination compared to other growing mediums. Sawdust blocks are pressure sterilized, reducing the chances of contamination and providing a clean and healthy environment for mushroom growth. This feature not only protects your crop but also reduces the time and effort spent on contamination management.

Wide Variety of Mushrooms

Sawdust blocks can be used to grow a broad range of gourmet and medicinal mushrooms. While some mushrooms, like oyster mushrooms, are versatile and can grow on various substrates, other species like shiitake and lion's mane, thrive specifically on sawdust blocks. Sawdust mimics the natural environment of these mushrooms, making it an ideal growing medium.

How to prepare sawdust for mushroom growth

Preparing sawdust for mushroom growth is a practical and popular method for cultivating mushrooms. This approach taps into the natural decomposition process that mushrooms thrive on, and it is a cost-effective and widely available method. Here is a detailed guide on how to prepare sawdust for mushroom growth:

Sourcing the Right Sawdust

Firstly, you need to source the right sawdust. Most gourmet mushrooms will only grow on sawdust from hardwood trees. You can use a wide range of hardwoods, but ensure it is fresh, clean, and does not contain any bits of bark or leaves. Make sure the sawdust comes from untreated wood, as mushrooms will not grow on treated wood. Hardwood pellets are a good option as they are readily available at local retail stores or online.

Mixing the Substrate

Next, you will need to mix your sawdust substrate. Combine your hardwood sawdust with supplements such as wheat bran or rice bran, which boost mushroom growth. A common ratio is 5 parts sawdust to 1 part bran. Add water at a rate of 1.5 to 1.7 times the weight of the dry substrate. The goal is to hydrate the mixture evenly to about 60-65% moisture, where the mix is moist but not dripping water.

Sterilization

Before inoculating your substrate, you must sterilize it to kill any unwanted bacteria or fungi. You can use a pressure cooker or autoclave to sterilize the mixture. Ensure your substrate has cooled down enough before inoculation, as high temperatures could kill the mycelium.

Inoculation

Inoculation is the process of adding mushroom grain spawn to your prepared substrate. Wipe down all work surfaces and clean your hands well with soap to avoid contamination. Add your mushroom spawn at the desired spawn rate to the wet substrate and mix them. Many people choose to mix them inside the bags, but it is easier to do this in a large box or container and then return the mixture to the bags.

Incubation

Store the inoculated substrate in a dark, clean space with a stable temperature suitable for your mushroom species. This is where the mycelium will colonize the sawdust. Maintain a stable environment, avoiding drastic temperature fluctuations and ensuring the incubation area is clean to prevent contamination. This process typically takes 2-4 weeks, depending on the mushroom species and environmental conditions.

Fruiting

Once the sawdust is fully colonized, it's time to encourage fruiting. Expose the substrate to fresh air, increased light, and a drop in temperature. Some growers make small cuts or holes in the bags to facilitate mushroom emergence. Aim to maintain the humidity around 85-95% for optimal growth.

The ideal humidity, temperature and ventilation conditions

Temperature, humidity, and ventilation are key factors in cultivating mushrooms. Mushrooms are highly sensitive to changes in their environment, so maintaining a consistent level of humidity and temperature is critical for their development.

The ideal humidity for mushroom cultivation is between 85% and 95%. Humidity is important because it affects the ability of mushrooms to absorb water through their cell walls. If the humidity is too low, the mushrooms may dry out and fail to develop properly. On the other hand, if the humidity is too high, it can promote the growth of harmful bacteria and fungi that can compete with the mushrooms for resources and cause disease. To maintain this level of humidity, growers may use various methods such as misting, watering, or using a humidifier in the growing area. It is important to monitor humidity levels regularly with a hygrometer and make adjustments as needed to ensure optimal growing conditions.

The ideal temperature for mushroom cultivation depends on the species of mushroom being grown. For example, some strains of blue oyster mushrooms thrive at temperatures between 70-72°F (21-22°C), while others prefer it colder or warmer. Generally, maintaining a steady temperature is important to keep condensation buildup inside the bags to a minimum.

Ventilation systems are essential for successful mushroom cultivation. They help maintain the right balance between the humidity of the mushroom bed and the air temperature, avoiding damage to the crop. Mechanical ventilation systems are often necessary for recycling and air changes in mushroom beds. Good air circulation is vital for providing fresh air and preventing the buildup of carbon dioxide, which can hinder mushroom development.

How to identify and respond to contamination

Growing mushrooms is a rewarding endeavour, but it requires a clean and sterile process for success. A single mould spore contaminating your substrate, jars, or equipment can ruin your entire mushroom culture. Therefore, it is important to identify and respond to contamination promptly to ensure a successful crop.

How to Identify Contamination

Contamination, or 'contam' in grower slang, refers to anything in your substrate or mycelium that negatively impacts your grow. This includes bacteria, moulds, and animal pests. Here are some common signs of contamination to look out for:

• Discolouration: Changes in colour, such as yellow or brown spots or streaks on the surface of the mushrooms or growing medium.
• Slime: Many common types of bacteria that can contaminate mushroom cultures can give the mycelium or grains a slimy appearance. This slime often occurs in areas where the substrate presses against glass, forming slimy rings around the grains.
• Foul Odour: If your kit is infected with bacteria, specifically the Bacillus genus, it will emit a significant sour foul stench.

How to Respond to Contamination

If you suspect contamination, it is important to act quickly as contaminated patches can quickly spread and endanger your entire crop. Here are some steps to respond to contamination:

• Sterilization: Proper sterilization of your substrate, equipment, and work area is crucial. Use a pressure cooker or a laminar flow hood to sterilize your substrate and eliminate unwanted contaminants like mould and bacteria. Ensure all your tools, such as scalpels, blades, and syringes, are also sterilized.
• Air Circulation: Good air circulation helps prevent the buildup of carbon dioxide, which can hinder mushroom development. Increase fresh air exchange by using fans to circulate air gently and prevent stunted growth and lower yields.
• Hydrogen Peroxide: If you detect mould, a 3% hydrogen peroxide solution can be sprayed on the infected area. After direct application, soak a paper towel in hydrogen peroxide and place it on the affected area to control future contamination.
• Cleanliness: Contaminants can be introduced through your clothes, skin, and hair. Ensure you are clean and wear freshly washed clothing before working on your mushrooms. Wash your hands thoroughly and consider using hand sanitizer to eliminate surface bacteria.

The best types of mushrooms to grow on sawdust

Growing mushrooms on sawdust is a practical and popular method for cultivating mushrooms. This approach mimics the natural environment in which mushrooms flourish, such as on forest floors and decomposing tree matter. Sawdust is also a cost-effective and widely available substrate.

Most gourmet mushrooms grow best on supplemented sawdust fruiting blocks. These blocks are typically composed of a ratio of 85% hardwood sawdust to 15% wheat bran. The sawdust should be inoculated with mushroom spawn and provided with the right conditions for growth. Here are some of the best types of mushrooms to grow on sawdust:

Oyster Mushrooms

Oyster mushrooms are one of the most popular varieties grown on sawdust. They fruit heavily and can be grown on straw logs or hardwood sawdust supplemented with nitrogen-rich wheat bran.

Shiitake Mushrooms

Shiitake mushrooms are another variety that thrives on sawdust. They are slow colonizers, taking around 3 months to fully colonize a sawdust block. To fruit shiitake, expose the colonized block to fresh air and place it in a humid area with temperatures between 50-85°F (10-29°C) and 60-85% humidity.

Lion's Mane Mushrooms

Lion's Mane mushrooms grow well on a range of hardwood sawdust types, including beech, elm, oak, maple, and birch. They also grow well on "Master's Mix." Lion's Mane mycelium is fine and wispy, and it can be challenging to determine when colonization is complete. However, a lion's mane fruiting block should be fully colonized within 2-3 weeks, after which you can expose the block to fresh air and high humidity to encourage fruiting.

Reishi Mushrooms

Reishi mushrooms can be grown in logs outdoors or in pans with sawdust. If growing outdoors, bury the logs to create a casing layer.

When growing mushrooms on sawdust, it is important to maintain high humidity levels (85-95% for most varieties), ensure good air circulation, and regularly monitor for moisture loss, contamination, or other issues.

Frequently asked questions