The Fascinating Process of Growing Mushrooms: A Step-by-Step Guide
Mushroom cultivation is a rewarding and sustainable way to produce food. Whether you're interested in growing them for personal use or as part of a larger farming operation, the process can be incredibly fulfilling. At Wild Plum Growers, we specialize in oyster, shiitake, and lion's mane mushrooms, and we want to share the general process of growing mushrooms—from substrate preparation to harvesting.
Let’s dive into the essentials of growing mushrooms at home or on a farm, starting with understanding the key components and steps involved in this fascinating process.
1. Understanding the Mushroom Lifecycle
Mushrooms are fungi, and their growth cycle is unique compared to other plants. Instead of seeds, mushrooms grow from tiny “spores” that are similar to seeds but much smaller. These spores grow into mycelium, a web-like root system that spreads through the substrate (the material in which the mushrooms grow). The mycelium breaks down the organic matter in the substrate, providing nutrients for the developing mushrooms. Once the mycelium has colonized the substrate, it produces fruiting bodies—what we recognize as mushrooms.
2. Choosing the Right Substrate
The substrate serves as both the food and the medium for the mushrooms to grow. It’s essential to select the right substrate depending on the type of mushroom you want to grow. Here’s a breakdown of what works best for different varieties:
Oyster Mushrooms: These are very versatile and can grow on a variety of substrates, including straw, sawdust, coffee grounds, and even cardboard.
Shiitake Mushrooms: Shiitakes are typically grown on hardwood sawdust, logs, or wood chips, as they naturally grow on dead trees in the wild.
Lion’s Mane Mushrooms: These require hardwood sawdust or supplemented sawdust to thrive.
The quality and preparation of the substrate are vital for success. The substrate must be nutrient-rich to support the growth of the mycelium and provide a proper environment for the mushrooms to fruit.
3. Sterilizing the Substrate
Sterilizing the substrate is a crucial step in mushroom cultivation. The sterilization process helps eliminate any unwanted bacteria, molds, or competing fungi that could hinder the growth of your mushrooms. There are several methods to sterilize the substrate, with the most common being pasteurization and sterilization.
Pasteurization: This method involves heating the substrate to a temperature of around 60–80°C for a set period of time. It’s a gentler process and is ideal for substrates like straw or sawdust. Pasteurization kills most harmful microorganisms without destroying the nutrients needed by the mycelium.
Sterilization: Sterilization involves heating the substrate to a higher temperature (121°C or 250°F) under pressure, typically in a pressure cooker or autoclave. This method is most effective for substrates that may have higher contamination risks, such as wood chips or certain organic materials.
Once sterilized, the substrate must be cooled before inoculating with mushroom spawn. Make sure the substrate is at room temperature before proceeding to the next step.
4. Inoculation with Mushroom Spawn
After sterilizing the substrate, the next step is inoculating it with mushroom spawn—the material that contains the mushroom mycelium. You can purchase mushroom spawn, which is usually sold as grains (like rye or millet) or sawdust inoculated with mycelium. There are different ways to inoculate the substrate, but the most common methods are:
Grain Spawn Inoculation: Grain spawn is mixed directly into the cooled substrate. The mycelium will then colonize the substrate, breaking down the organic material and providing nutrients for fruiting.
Plug Spawn Inoculation: For log-based mushroom cultivation (such as shiitake), plug spawn is inserted into pre-drilled holes in logs. The mycelium spreads throughout the wood over time.
When inoculating, it’s essential to work in a clean environment to avoid contamination. Wearing gloves and sterilizing your tools is highly recommended.
5. Incubation and Mycelium Growth
Once the substrate is inoculated, it’s time for the mycelium to colonize the substrate. This is called the incubation phase. The inoculated substrate should be kept in a warm, dark place with temperatures typically between 20–24°C (68–75°F) for most mushroom species.
During this period, the mycelium will begin to grow and spread throughout the substrate. Depending on the mushroom species, this process can take anywhere from a few weeks to several months. It's crucial to monitor the substrate and ensure that the temperature and humidity are stable during this time.
Signs of successful colonization include:
The substrate will turn white as the mycelium spreads.
There will be a slight earthy or mushroom-like smell.
The substrate will feel firm and dense when squeezed, indicating that the mycelium has fully colonized it.
6. Fruiting Conditions and Initiating Pinning
Once the substrate is fully colonized by the mycelium, it’s time to trigger the fruiting stage, where the mushrooms will begin to form. This is called pinning, where tiny mushroom primordia (pinheads) appear.
To initiate fruiting, the substrate should be moved to a cooler, more humid environment with access to light. Ideal fruiting temperatures vary by species but generally range from 15°C to 24°C (59°F to 75°F).
You should also increase the humidity levels to around 85–90%, which can be done by misting the substrate regularly or using a humidity tent. Adequate airflow is essential to prevent excess moisture buildup, which could lead to mold.
7. Harvesting Your Mushrooms
Once the mushrooms begin to grow, you’ll see them expand rapidly, and after about 3–7 days (depending on the variety), they will be ready for harvest. Mushrooms should be harvested when the caps are fully expanded but not yet flattened.
To harvest, gently twist or cut the mushrooms at the base of the stem. Be careful not to damage the substrate, as it may continue producing multiple flushes of mushrooms. After harvesting, you may need to mist the substrate again to encourage another round of growth.
8. Post-Harvest Care
After harvesting your mushrooms, you may want to continue using the substrate for subsequent flushes of mushrooms. It’s essential to continue maintaining the correct humidity and temperature conditions, and you can often get several flushes of mushrooms from the same substrate.
Once the substrate has stopped producing mushrooms, you can compost it to enrich your garden soil.
Final Thoughts
Growing mushrooms can be an incredibly fulfilling process that connects you with nature and provides fresh, sustainable food right at your fingertips. Whether you’re growing a small batch at home or starting a larger-scale cultivation operation, understanding the steps from substrate preparation to harvesting is key to a successful mushroom harvest.
At Wild Plum Growers, we’re passionate about making mushroom cultivation accessible to everyone, and we hope this guide helps you start your own mushroom-growing adventure. Ready to get started? Grab one of our Mushroom Grow Kits and let us guide you every step of the way!
