Certain wood loving mushrooms need special substrates to grow on such as Lions Mane, Shiitake, King Oyster, Chestnut, Enoki, Reishi and Shimejji to name a few.
These mushrooms are saprotrophs and they get their nutrition from decomposing organic matter that’s high in woody, fibrous materials like lignin, cellulose and hemicellulose
As sawdust is pulverized wood, it contains the same organic material as logs or stumps, just in a different form. Sawdust is an excellent substrate for wood-loving mushrooms, but not just any sawdust. It’s important to use the right sawdust. Otherwise, your attempts to grow mushrooms may be unsuccessful.
Which types of sawdust can you use ?
Most gourmet mushrooms will only grow on sawdust from hardwood trees. But, you can also use softwood sawdust in certain instances to grow some mushroom species.
You can use a wide range of hardwoods, but some are not as easy to source and more expensive than others. We recommend using whichever hardwood sawdust you can source locally. You can buy hardwood sawdust, make some at home or collect sawdust from local factories and sawmills, but, wherever you source it, make sure it’s fresh and clean and does not contain any bits of bark or leaves.
Another thing to check, if you are sourcing your sawdust from a factory, is that all the sawdust comes from untreated wood. Mushrooms will not grow on sawdust from treated wood.
Can you use wood shavings?
Yes, you can use hardwood shavings as your source of sawdust.
People often mix finer sawdust with wood shaving or fine wood chips to improve aeration in their substrate. If your sawdust particles are too fine, they may compact, preventing airflow and creating anaerobic conditions in the middle of your sawdust block during incubation. These conditions will prevent the mushroom mycelium from fully colonising the substrate.
Types of hardwood block recipes:
Sawdust With Wheat or Oat Bran
Many mushroom growers use wheat or oat bran as the nitrogen-rich supplement in their sawdust block recipes. They’re a popular choice because they’re inexpensive and readily available. Small bags are available at grocery stores and supermarkets. But, a less expensive option is to buy larger quantities from animal feed stores. When using bran, add it at a rate of between 10 and 20 percent of the dry weight of the sawdust before adding water.
Master’s Mix is a popular nutrient-rich sawdust block recipe using 50 percent sawdust + 50 percent soybean hulls
How to make a hardwood fruiting block
Gather your supplies, you will need :
Hardwood sawdust + Bran Flour + gypsum
Mushroom grow bags with filters, the best bag for this is the Unicorn 14A bag
The goal when preparing your substrate is to mix the sawdust and supplement and hydrate it evenly to 60 percent.
First, measure out your sawdust and supplement and combine them in a large tote, bucket or similar container.Now add water at a rate of around 1.5 to 1.7 times the weight of the dry substrate and mix.
The easiest way to mix substrate is by mixing it up with your hands. Remember to wash your hands thoroughly before you begin, or consider wearing disposable gloves.
Alternatively, you can use a large spoon, sturdy plastic scoop or even a shovel if you’re mixing lots of substrate.
Before adding your mixed substrate to your bags or containers, you need to test it to ensure it has the right amount of moisture.
The easiest way to test is to pick up a handful of the mixed substrate and do a squeeze test.
Squeeze the handful of substrate lightly. If more than a drop or two of water comes out, it’s too wet, and you need to add some dry substrate to adjust it.
If no water comes out and the substrate isn’t staying together in your hand, it’s too dry, and you’ll need to add a little water.
When you have thoroughly mixed your substrate, and it’s suitably moist, put it into your grow bags.
Then, squeeze out as much air as possible and fold the bags according to instructions.
Now it’s necessary to sterilise your substrate in a pressure cooker to kill off unwanted contaminants like mold and bacteria.
Place the bags in a pressure cooker making sure to use jar lids or a rack of some kind to keep your grow bags from making direct contact with the bottom of the pressure cooker and burning.
Also, remember to weigh down the bags with a plate or something heavy to prevent them from blocking the pressure relief valve on the pressure cooker lid.
Pressure sterilise your bags for three hours at 15PSI.
Then turn off the heat and allow the sterilised substrate to cool in the pressure cooker for at least 8 hours.
Inoculation is the process of adding mushroom grain spawn to your prepared substrate.
Before you begin, wipe down all work surfaces and clean your hands well with soap to avoid contamination.
Ensure your substrate has cooled down enough as high temperatures could kill the mycelium. 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’s easier to do this in a large box or container and then return the mixture to the bags. It’s best to inoculate your sawdust block in front of a laminar flow hood, a workstation that helps prevent contamination.
Laminar flow hoods provide an uninterrupted steady flow of filtered clean air and are a good idea for a small-scale mushroom growing business.
But, if you’re new to mushroom growing, you can use a still air box.