Growing shiitake mushrooms indoors is a simple alternative to growing them in your own garden.
You may start lowering your grocery bill and carbon footprint without ever going outside simply by using a bag of sawdust and a black room!
Growing shiitake mushrooms takes place either on logs or in bags of nutrient-enriched sawdust or other organic material, called bag culture.
Bag culture is a complex process requiring specific conditions of the controlled temperature, light, and moisture.
What You Need:
• 5 cups of hardwood sawdust pellets or fresh sawdust:
Shiitake mushrooms grow best on the oak substrate (the word “shiitake” means mushroom of the oak).
If you don't have access to oak sawdust, you can substitute it with other deciduous hardwoods like beech, ironwood, or maple.
• 5/8 pounds shiitake mushroom grain or sawdust spawn
• 1 ¼ cups wheat bran
• 5 lb grow bag with filter patch
• Cloth or paper filters
• Large tub
• Rubber gloves
• Pressure cooker (optional)
• Heat-proof gusseted plastic bags (optional)
• Jar lids (optional)
Step for Growing Your Shiitake Mushrooms:
1: Heat Sawdust to Pasteurize
The substrate needs to be pasteurized (exposed to high temperatures) before it is inoculated with mushroom spawn.
Pasteurizing eliminates any microorganisms like fungi or bacteria that could kill or otherwise harm your shiitake mushrooms.
This step is key for keeping mold from growing in what would otherwise be its ideal breeding environment (a cold, dark, damp bag).
Fill a large tub halfway with water and set outside (if you can). Place the grow bag in the tub. Fill the grow bag with as much sawdust as possible; it should not be spilling out of the top. DO NOT USE HOT WATER.
Hot temperatures may kill beneficial organisms and you could end up with a bag full of mold.
The manner in which you prepare your substrate, however, is determined by the type of material you're using.
If you're utilizing sawdust pellets, they've already been pasteurized and simply need to soak in 1.4 liters of water for 30 minutes to break down the pellets into usable sawdust. You may also pasteurize normal sawdust.
2. Sterilize The Substrate
Some shiitake growers suggest sterilizing your substrate in addition to pasteurizing. While this is not always necessary or possible if you are able to sterilize your sawdust it can only improve your shiitake mushroom growing conditions.
In addition to pasteurizing, some shiitake producers recommend sterilizing your substrate. If you can sterilize your sawdust, this is not always necessary, but it will only enhance your shiitake mushroom growing environment.
Fill a heat-proof plastic bag or bags with pasteurized sawdust to sterilize your substrate.
While the sawdust is cooling, insert a filter between the gussets to keep it safe from contamination.
Fold down the gussets after filling them with pasteurized sawdust. Filters can also be made out of Tyvek or scraps
Stack the bags in your pressure cooker, then place jars on top to raise the bags and fill.
Fill the pot only halfway with water, then put something heavy (a plate will work) on top of the last bag to keep it from clogging the relief valve.
You run a chance of damaging high levels of pressure building up if you don't add a weight
Leave the heat on high for at least an hour after pressure is reached in order to kill any harmful bacteria or fungi that may have survived pasteurization.
You can then dispense with the jars and just leave the bags in your sterilizing solution until it is time to inoculate them with mushroom spawn.
3. Inoculate Your Grow Bags
The process of introducing mushroom spawn to a substrate is called inoculation. Inoculation needs to happen in a clean area, so wipe down any surfaces you will be using, including a large plastic tub, with a disinfectant.
Wearing disposable rubber gloves is also recommended. Before you begin, check the water content of your pasteurized or sterilized substrate.
When you squeeze the sawdust, a few drops of water should come out, but not more.
If you are inoculating your substrate with sawdust spawn, you should find the sawdust pellets have already been inoculated prior to purchase.
If not, there are two methods of adding spawn to your substrate. There are two ways to introduce the spawn into your substrate.
First, you can use a large spoon or ladle to distribute it even throughout (make sure you sterilize your utensil first).
If that sounds like too much work, there's always the option of injecting your substrate with sawdust spawn using an injector bag or syringe.
While shiitake producers have differing opinions on the matter, research has shown that four holes bored into the bag with a drill is sufficient to inoculate your substrate.
Use an injector bag or syringe to introduce sawdust spawn at 1cm intervals into each hole.
If you are using pasteurized sawdust instead of sterilized, you should cover the top of your bag to keep-out contaminants that may be present in the sawdust
In the clean plastic tub, gently mix the substrate, wheat bran, and grain or sawdust spawn. Once incorporated, transfer the sawdust spawn mixture to your grow bag and close it with tape, a rubber, band, or a zip tie.
Place sawdust spawn bags into a plastic tub or other clean, disinfected surface. You can then open them and pour the substrate into your pasteurized/sterilized grow bags.
Hand squeeze as many pellets as possible to break up clumps, then let the inoculated bags sit for two to three weeks. You can mix or rotate them slightly once a week if you feel it is necessary, but this is not always necessary.
4. Prepare the Casing Layer
One of the most important steps in mushroom cultivation is covering the inoculated substrate with a "casing layer." The casing keeps the substrate moist, suppresses unwanted micro-organisms (molds), and may provide nutrients.
Although at first glance it may seem that the casing layer is only there to help the shiitake mushrooms absorb more water and nutrients, this is untrue.
It's actually the opposite: The mycelium (the vegetative part of a fungus) needs moisture in order to survive; without proper hydration, mushroom growth will be stunted.
If the casing layer is too thick, however, it will act as a barrier to moisture and prevent water absorption. This can result in insufficient nutrients for mushroom growth (when nutrient-deficient mushrooms fruit).
So the proper thickness of the substrate casing layer must be determined by trial and error. Pand wax is two substances that can be used as a casing layer.
Petroleum jelly (Vaseline) and wax are two substances that can be used as a casing layer.
Here is how you make the Vaseline-cased substrate: Place your inoculated bag on some newspaper outside (it doesn't need to be pasteurized again petroleum jelly (Vaseline)to the top.
The wax-cased substrate is made by placing your inoculated bag in a pot or bucket full of water, then adding one part paraffin wax to ten parts water (by weight).
If you are concerned about bees and other beneficial insects like butterflies who might not appreciate the smell of petroleum jelly near their home, use wax instead.
5. Incubate The Shiitake Spawn
When gardening inside, the right location is everything. Luckily, shiitake mushrooms need just a few things while they’re incubating: nutrition, and a dark, humid environment.
One 5 pound bag equals approximately 5 inches wide by 8 inches deep, and around 18 inches tall. Choose a location off the ground that is slightly bigger than your bag.
The space should not get a lot of sunshine, but it should have a medium level of humidity (around 65%). Keep the bags in a cool or comfortable room like a bathroom or cellar.
6. Induce Fruiting
Mushrooms do not grow on their own; rather, they must be "shocked" to produce fruit, as is the case with shiitake mushrooms.
Shocking mimics natural environmental changes that a shiitake mushroom would encounter while growing outdoors. While a physical strike simulates the impact of a tree falling, a cold shock informs
Pick a spot that is consistently between 37 and 41 degrees Fahrenheit (3 and 5 degrees Celsius) to cold shock the incubated block.
This may be done outdoors in the winter, in a large cooler, or inside your fridge. The key to cold shocking is for the spawn to have a substantial temperature change.
so it's less important than the difference between daytime and nighttime temperatures.
You can also smack the bag of shiitake mushroom spawn with your hand on all sides before moving it into a cold shock.
After shocking the shiitakes, you may remove the substrate block from the bag and place it in a humid area with plenty of airflows. Mist the block with water several times a day, and after about a week, your block should begin fruiting.
7. Harvest Your Shiitake Mushrooms
Harvesting is done by cutting the stalks (called "logs") off of the mushrooms with a sharp knife or pruning shears. Take care not to damage the stalks, as this will result in mushroom rot.
After harvesting, you can cut the stems into little rounds and stir fry them up for some tasty shiitake mushrooms!
It is possible that you may find some other edible mushroom growing in the same area as your shiitake blocks.
If this is undesirable, you can spray the bags with a weak bleach solution (about 1 part bleach to 20 parts water) while they are hanging.
8. Storing Your Shiitakes
The time between spawning and fruiting is usually around three months, but it may take longer for some bags.
Shiitake mushrooms can be stored for several months without losing their quality and flavor but should be used within a year to ensure freshness and taste.
Keep your blocks in the same conditions as you would if they were fruiting: minimal sunlight, cool temperatures and high humidity levels.
The blocks will keep longer if kept in an unsealed, breathable bag rather than a plastic one.
This will allow the block to draw in just a little bit of moisture from the environment to keep itself alive. You can also lay your blocks on a sheet that is propped up slightly higher in all four corners at about a 60-degree angle.
The sheet should be slanted towards one side of the bag, and a fan should be set up to blow over the block from behind. This will ensure maximum airflow while still maintaining humidity levels.
To keep your blocks alive, seal them in a plastic bag. You can punch several small holes in it for ventilation. Store at about 60 degrees Fahrenheit for a few months, but try to use them within a year.
9. Maintaining Your Shiitake Growing Substrate
After you harvest shiitake mushrooms from your substrate, allow them to rest for at least three months before reusing the material. This allows residual mycelium to develop and absorb nutrients for future growth.
You can reuse your substrate to grow mushrooms again by placing it in a plastic bag, then storing it in a cool, dark location until you are ready to use it again.
If the substrate hasn't been used previously, however, you should add additional sawdust (fresh or sterilized) and water.
10. Maintaining Your Growing Area
Mushrooms require a high-humidity, moist environment to thrive. This prevents them from drying out and promotes optimal fruit body development.
Misting once or twice daily should be enough to keep your growing area wet and prevent fruiting bodies from drying out.
You may add a casing layer after the two-week mark if you like.
Growing Shiitake mushrooms at home - why not give it a try?
Shiitake mushrooms are easy to grow at home, and they can be used in a variety of different recipes.
Once you know what you're doing, it's easy to adapt this method for growing many other types of edible fungi!
If you want any more help or advice, leave us a comment below. We'd be glad to help!