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How to grow mushrooms

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Generally speaking, the first step in growing mushrooms is to create grain spawn.  This can be done several ways, by adding tissue from a petri dish or slant to sterilized grain, or by squirting 2 to 6 ml of liquid culture onto sterilized grain.  You can even add spores to sterilized grain to start growing a unique strain of a particular culture.

Let's take one step back and understand some basics about mushrooms.  Mushrooms are classified as their own Kingdom, Kingdom Fungi.  Fungi “breathe” oxygen and "exhale" carbon dioxide similar to animals. Mushrooms are the fruiting bodies of a fungus.  The mushroom fruiting body is how some fungi reproduce.  The actual being of the mushroom consists of a network of tiny strands collectively called mycelium.  Mycelium of gourmet mushroom fungus tends to live in dead or dying hardwood trees.  There, the mycelium breaks down wood fibers into food, and grows until it encounters the boundary of its resources.  At this point, along with other factors such as temperature and humidity, the fungus will put energy into producing its fruiting bodies, mushrooms!  These mushrooms produce spores that will hopefully land on another food source, such as a freshly fallen tree, and start the entire cycle again. 

An analogy to understand mycelium or the living body of fungus and its fruiting bodies (mushrooms) is as follows.  Imagine that an apple tree, including its roots, trunk, branches, and leaves all grow underground just below the soil surface, and when this apple tree produces an apple, it pops out of the ground just like a mushroom.  Its apple seeds are so small and light that they can float in the wind to more suitable locations, just like spores do to start a new network of mycelium.


Please note that sterile technique should be used whenever necessary.  This is extremely important for growing sterile cultures successfully.  Books such as Growing Gourmet and Medicinal Mushrooms by Paul Stamets, Radical Mycology by Peter McCoy, and Organic Mushroom Farming, and Mycoremediation by Tradd Cotter are excellent resources to learn sterile technique and much more.

Also, we use distilled or reverse osmosis filtered water in our pressure cooker, for hydrating grain, for simmering grain, and for hydrating fruiting substrates.  Note that when we mention using water, we are referring to non-chlorinated water.  Distilled water can be purchased at grocery and department stores.  Reverse osmosis filtering systems can be purchased online or in stores.  Tap water can be left out for 24 to 48 hours to allow the chlorine to dissipate, but we don’t recommend using tap water in pressure cookers.  The minerals can interact with the cooker and degrade it over time. 

Grain Spawn 101

The basic idea behind grain spawn is that you are creating "the seeds" to plant mushrooms into their fruiting substrate, such as hardwood sawdust.  The mushrooms will grow on the sawdust.  The easiest way to create grain spawn is by adding liquid culture to grain.  Below are some grain spawn recipes that work for us. 

Grain Spawn Jar Recipe (The Soak and Simmer Method)

The most reliable method of creating grain spawn is the "soak and simmer" method.  The first thing you need to do is hydrate your grain.  You'll want a quality grain, such as rye berries, to cultivate your mushroom fungus.  We soak our grain  for 24 hours before draining, rinsing, and simmering on the stove for 10 to 20 min.

Here is what you do.  Start with pint or quart sized jars such as Ball Mason jars, and fill them with rye grain, 1/3 full. Repeat this step as needed to prepare the desired amount of grain.  For example, if your pressure cooker can fit 6 jars and you want to inoculate that much grain, repeat this step 6 times. 

Ultimately, when the grain is hydrated, it will expand to double its volume, so your jars will be 2/3 full. Pour the grain from the jars into one container and soak it in non-chlorinated water for 24 hours.  Make sure the water level is 3 or 4 inches higher than the dry grain so there is extra water for the grain to absorb; you don’t want to end up with dry grain at the top. If you soak the grain too long, the rye grain will begin to sprout.  Somewhat sprouted grain can still be used, but is undesirable due to the increased risk of contamination.  After the 24 hr. soaking, drain and strain your grain.  Also, rinse your grain until the water runs clear.  Put your clean soaked grain into a pot and simmer it for 10 to 20 minutes.  Ideally, you want your grain to swell to its full capacity without bursting.  If you start to see burst grain, take your grain off the stove immediately.  They will work fine at this point, but you cooked them a little too long.  The next time you prepare grain spawn, cook it for a few minutes less and you'll have perfect grain!  After you perform this step a few times, you’ll get good at knowing what fully hydrated grain looks like.  Easy peasy!

Now that your grain is simmered, take it off the stove and strain it while hot.  We spread our grain out in trays or on a table, so they can dry through evaporation.  Stir your grain around periodically until it is fairly dry on the outside.  Pick up a handful when you think your grain is dry enough and drop it.  It shouldn't leave very much water behind, if any. 

At this point, your grain is almost ready!  The final step before sterilizing your grain is to add some gypsum powder and mix it in thoroughly.  Add 1 teaspoon per quart jar of grain spawn, or 2-8% gypsum by dry weight of grain.  Mix the gypsum in thoroughly so the grain is covered evenly.  Gypsum adds minerals (calcium sulfate) that help your fungus grow, and keeps your grain from sticking together after sterilizing it.

Load your grain into pint or quart sized jars a little over half way full.  Screw on a cultivation lid that has a built in air filter or a lid with an air filter and injection port.  Cover the lid with tinfoil to protect your grain from excess moisture that can penetrate through the air filter during sterilization.  Too much water is not good for growing fungus.  Extra water tends to pool on the bottom of jars and create an anaerobic space where fungus can't colonize, but contamination such as bacteria can.  Put your jars on a rack in a pressure cooker and add a couple inches of distilled water to the bottom.  Cook your grain jars for 3 hrs at 15 psi, typically 250° F.  A three hour cook time is a little longer than absolutely necessary, but we like to be 100% sure our grain is sterile.  After your grain has cooled to room temperature, or at least under 95° F in the center of your jar, you can inoculate your grain with mushroom liquid culture, colonized agar (petri dish or slant tissue), or spores from a spore print.

How to Inoculate Grain Spawn with Mushroom Culture

  • Liquid culture inoculation of grain spawn- 
    If you are using a lid with an injection port, inoculations can be done in open air, but we always recommend using a still air box or laminar flow hood whenever possible.  If that last sentence went over your head, learn sterile technique!  Shake up the liquid culture in the syringe to get the mycelium pieces floating around in the liquid.  Spray the injection port of the grain spawn jar and the liquid culture syringe with 70% rubbing alcohol and let it clean any potential contaminants for a minute or so.  Push the needle through the injection port on the grain jar and inject 2 to 6 ml of liquid culture onto the grain.  It helps to spray some on grain next to the glass so it can easily be seen colonizing. If you are using a lid without an injection port, you can simply twist off the grain jar lid and squirt a few ml of liquid culture onto the grain.  Be extra clean and follow sterile technique if you are taking the lid off your grain spawn jars.  Contaminants like to eat grain too.  Typically, it will take 2 to 4 weeks for your grain to be fully colonized by mycelium, but this is dependent on which mushroom species you are trying to grow.  When the grain is about 1/3 colonized, you can shake the jar to break up the colonized grain and redistribute it evenly throughout the jar.  This will speed up colonization significantly for most species.  Be careful not to break your jar!  We smack our jars against dual density foam designed for car seats, that we stacked in three layers.  It’s also very helpful to break up the colonized grain in your jars before inoculating fruiting substrates.  We’ll add more on this later.
  • Agar inoculation of grain spawn- Agar inoculations require a still air box or laminar flow hood to have consistent high levels of success.  In front of a flow hood, grain spawn jar lids can be taken off, and pieces of colonized agar from a petri dish or slant can be placed in the jar to inoculate it.  Sterile technique should be followed during the procedure. 
  • Spore inoculation of grain spawn- Spores are the true “seeds” of mushrooms and can be used by placing a small amount directly on sterilized grain.  This should be done in a sterile environment.  Grain is highly nutritious and can contaminate easily if not handled using sterile technique.  When inoculating grain with spores, you’ll produce unique strains of the fungus that have very young genetics.  Mating spores on grain is like mushrooms having children.  The “kids” are genetically different from the parent(s), but can be very similar too.  One disadvantage of using spores is you may have several unique fungal “kids” growing in the same grain jar, competing for resources.  Ideally, you would isolate one strain to continue propagating, so you aren’t growing multiple strains together.  Growing an isolated strain will produce much better mushroom yields.  Isolating a strain can be as easy as taking a small tissue sample from an area of mycelium that appears uniform and healthy.  Put this tissue sample on a petri dish or in another grain jar to let it continue growing.  As it grows, check for contamination and see if it's growing uniformly.  Eventually use this isolated strain to grow your mushrooms. 

Gas Exchange Lids

Mushrooms, like humans, “breathe” oxygen and "exhale" carbon dioxide.  It's important for mycelium health to have it in a container that is sterile, but one that can also breathe. Without gas exchange, eventually mycelium will die in a jar or other container from suffocation.

  • Gas exchange lid for liquid culture-  We make, use, and sell metal wide-mouth Mason jar lids that have been upgraded with super heavy-duty injection ports and syringe filters for gas exchange.  It's by far the easiest option for making liquid culture with a very high probability of success.  Purchase a lid from us at Cloud Culture Mushrooms by clicking on the link.

Cloud Culture Liquid Lid


  • Gas exchange lid for grain spawn-  This is the easiest, cheapest, and most effective DIY method for making your own grain spawn lids.  Gather a Mason jar lid, a trim nail, and a hammer. Pound two holes in the lid, spaced out toward the edges.  Hammer down any sharp edges.  Take Tyvek sheets and cut out squares that are an inch wider than the top your jar.  105g Tyvek sheets are easy to find on  The Tyvek acts as the air filter.  After your prepped grain is in the jar, put your Tyvek square over the top of the jar, put the lid with 2 holes on top of the Tyvek, and press down to seat the Tyvek.  Then add the Mason jar ring and screw it down.  Having Tyvek on the bottom of the lid makes shaking the grain much easier after sterilization. 

Cloud Culture Grain Spawn lids are coming soon!  Expected availability is early 2021.   

Incubating/Colonizing Grain spawn

You've made grain spawn!  Now all you need to do is wait for it to colonize.  This can take one week to several depending on the species you are growing and the incubating conditions.  Optimal colonizing conditions for many gourmet and medicinal mushrooms species is 70°-75° F and 60-70% humidity.  The temperature is more important than humidity, but you'll get more mushrooms if your blocks don't dry out too much while colonizing.  Shake your jars to evenly distribute the colonized grain when you can see that the mycelium has colonized 1/3 of it.  This will accelerate colonizing significantly.  Your grain spawn will be ready when it's fully colonized.  Also, over colonized grain can be extremely difficult to break up, so don't let your grain jars sit too long before using them.  Immediately before using your grain spawn to inoculate fruiting substrate, shake and break up all the grain one final time to create as many inoculation points as possible.  This grain will be mixed in with fruiting substrate or used to make more grain spawn. It also adds nutrition to the final fruiting block allowing the mycelium to quickly colonize the substrate.

Making Fruiting Substrate for Wood Loving Species

Many gourmet mushroom species live on hardwood. To grow mushrooms indoors, we mimic this by using hardwood sawdust. 

  • Sterilized fruiting substrate-  A great substrate mix to use is known as "masters mix," consisting of 50% soy hulls and 50% hardwood sawdust. Hydrate your chosen substrate to approximately 60% and place it in jars with filter patch lids or autoclave-able filter patch bags.  Pressure sterilize at 15 psi for 3 hours to ensure full sterilization.  Now your fruiting substrate is ready to be inoculated by grain spawn!  Hard wood fuel pellets (HWFP) are often used as a source of sawdust.  Presoaking your HWFP helps to break it up evenly and turn it back into sawdust.  Here are four fruiting block recipes that work well.
    • HWFP, wheat bran, and gypsum (wheat bran @ 20% dry weight of HWFP, gypsum @ 2% dry weight total)

    • HWFP, soy hulls, and gypsum (50% HWFP & 50% soy hulls, gypsum @ 2% dry weight total)

    • Hardwood sawdust, wheat bran, gypsum (wheat bran @ 20% dry weight of HWFP, gypsum @ 2% dry weight total)

    • Hardwood sawdust, wood chips, wheat bran, gypsum  (wood chips @ 15% dry weight of hardwood sawdust, wheat bran @ 20% of combined wood chips and sawdust dry weight, gypsum at 2% dry weight total)

  • Pasteurized fruiting substrate-  Pasteurizing substrates doesn't completely sterilize it, but provides a window of time for fast colonizing mushroom cultures.  To pasteurize substrate, heat the substrate submerged in water to 160-180° F for 60 minutes.  Don't allow the temperature to rise above 180 degrees.  Doing this will kill the good bacteria and potentially allow the bad to thrive.  Pasteurizing works great for growing mushrooms outside, and takes less time, effort, and equipment than full sterilization.  We’ve had much success growing several species of mushrooms using pasteurized substrates, but oyster mushrooms and lion's mane are probably the easiest. 

Inoculating Fruiting Substrate

Inoculating your fruiting substrate is easy once you’ve determined a method to use and have learned the basics of sterile technique.  Generally, you need to get colonized grain mixed into your final fruiting material, such as masters mix.  This needs to be done in an extremely clean way, ending with a good seal of the final fruiting substrate container if you’re growing mushrooms indoors.  Make sure your lid or bag has a filter patch to allow your fungus to breathe.  Mix grain spawn into your fruiting material at 10 to 20% wet block weight.  Again, this needs to be done using a sterile technique method.  Here are a couple of ways you can do this.

  • Laminar flow hood-  Inoculating in front of a laminar flow hood is the most ideal method.  Flow hoods create a sterile, even, steady stream of air, preventing contaminants from settling on your cultures, grains, fruiting blocks, petri dishes, slants, spore prints, etc.  Follow sterile technique best practices when using a flow hood, for best results.  The downside is that building or buying a flow hood is costly.  Typically, from $300 to $1,000 or more depending on the size of the HEPA filter.  Use 99.99% HEPA filters that filter down to 0.3 microns.
  • Glove box/still air box-  Much success can be achieved with a simple glove box or still air box.  Glove boxes are a sealed environment and may have a positive pressure filtration system installed.  To use a glove box, you place your hands into gloves that are installed through holes in the side of the box.  This seals outside air from entering the box, but allows you to use your gloved hands to work with mushroom cultures.  The downside to using a glove box is that you sacrifice mobility and dexterity, which are important when working with mushroom cultures.  We prefer to use a still air box with open holes in the sides where you stick your hands through.  Wear nitrile gloves and sterilize the inside of the box and your gloves with a disinfectant spray (70% rubbing alcohol).  Also, adding a clear plastic flap right above the hand holes that covers the holes after your hands are removed is a  nice addition.  It keeps contaminants from drifting into the box while you aren't using it, and while you are waiting for the disinfectant spray to settle inside the box.  You can easily make your own still air box by buying a clear tote and cutting 2 large holes in the sides that you can stick your hands and forearms through.  Use sterile technique to minimize contamination while using your still air box. 
  • Flame method-  It’s possible to achieve a small sterile/mostly sterile space using a candle, torch, or other flame.  The heat of the flame creates an updraft, thus creating an umbrella shaped, mostly sterile, space just below the height of the flame.  The updraft created by the flame prevents contaminants from settling on your work.  Much mushroom culture success can be had with this method, especially with fast colonizing species such as oyster mushrooms.  We recommend using a still air box or flow hood rather than this method.  The main advantage of this method is the low cost and ease of setup.
  • Open air inoculations indoors or outdoors-  Believe it or not, indoor air, including the air in our homes, is much more "dirty" than outdoor air.  For this reason, inoculating pasteurized substrates can be done outside without worry and with great success.  If you choose to do any open-air inoculating in your home, turn off the HVAC system and spray a disinfectant in the air space twenty minutes prior to inoculating.  This will allow for suspended contamination-causing particles to settle and be cleaned by the spray.   We also follow this air cleaning practice when using a still air box or the flame method.  It’s not preferred over a laminar flow hood, but will increase your odds of success.

Incubation/Colonizing Fruiting Substrates

Maintaining humidity in your substrate colonizing space will help boost yields.  As your grain, sawdust, or other materials colonize in their containers, they slowly loose moisture through the filter patch or air exchange filter.  Generally, this isn’t a problem for grain spawn, but for longer colonizing species, or for over-colonized fruiting substrates, this can decrease mushroom yields.  Try to keep your colonizing area humidity level around 60 to 70%. 

Some mushroom growers like to shake up their fruiting blocks part way through colonization in an attempt to speed up the process.  We've found that fruiting blocks preform well by simply letting them colonize on their own after being inoculated by grain spawn.

Many gourmet mushroom species only take 1 to 3 weeks to colonize fruiting substrates. This is dependent on many variables including colonizing temperature, species, genetics, substrate formulas, humidity, and inoculation rate.

Indoor Fruiting Space

Indoor fruiting spaces can vary widely, depending on how much area is available and how many mushrooms are desired.  They can be as small as a 32-quart tote or as large as entire buildings.  We recommend starting with a tote if it's your first time growing mushrooms.  If you desire more mushrooms, upgrade to a small grow tent.  There are many different sizes of grow tents that work very well.  These are usually constructed out of a metal or plastic frame covered with heavy fabric.  The inside is usually covered in a reflective coating.  Another grow space option is a small greenhouse.  They can be purchased on Amazon for under $100 and are basically wire shelving with a plastic cover.  With a few modifications, they can work great.  Beyond this, entire rooms, your garage, an outbuilding, etc. can be converted into a mushroom fruiting space.

Totes are great for growing mushrooms, and are inexpensive to set up.  There are many YouTube videos about how to construct monotubs which are essentially a big tote (30-120 quart size) with 1 inch holes drilled in the sides.  We usually drill 4 holes on the two long sides with 2 holes toward the top and 2 holes 6 inches from the bottom.  We also drill one on each end in the middle.  These holes can be taped over with 3M Micropore Tape™ or stuffed with poly fill to allow for gas exchange.  It will also keep humidity in and contaminants out.  An easy way to maintain humidity is by putting 4 inches of perlite on the bottom of the tote and hydrating it to holding capacity.  You want it to be completely saturated without puddles forming on the bottom of the tote.  The perlite will slowly allow the water to evaporate over several weeks, allowing your mushrooms to grow. 

The design of larger fruiting spaces should allow for the floor to be continuously wet.  Since the humidity is often approaching 98%, water can build up on the floor.  Make sure you account for lots of water in your design.  You’ll also need the ability to vent air into and out of your fruiting space.  For room-sized fruiting spaces, you need to allow the air to be exchanged many times per hour, either scheduled by a timer or activated by a C02 sensor.  Ideally, you’ll be able to blow the heavy C02 and spore laden air outside.  Also, investing in a C02 sensor is a good idea for managing your fruiting space and keeping your home healthy if you grow mushrooms in hour house. 

The majority of gourmet and medicinal mushroom species like to grow in temperatures ranging from 40° to 85° F.  For best results, know your mushroom species, and plan on fruiting them when you know that you can maintain the specific temperature in your fruiting space over a given period of time.  Keep in mind that some species need a couple of months to produce multiple flushes of mushrooms. 

Controlling and maintaining proper humidity is also key to getting your fungus to fruit.

Fruiting Your Mushrooms 

Once full colonization of your fruiting substrate is complete, your fruiting blocks can be stimulated to fruit by controlling 5 main variables; temperature, humidity, air exchanges, light, and timing. 

Temperature- Most mushrooms fruit within a specific temperature range.  Knowing this range allows the grower to manipulate the temperature in their fruiting space to produce mushrooms.  Simply, maintaining the temperature in the middle of your mushroom's ideal fruiting temperature range can yield great results, but different species may prefer variations in temperature over time for best results.  Some species even require a cold shock in order to fruit.  Learn what works for the specific mushroom culture you’re growing.

Humidity- Many mushroom species need high humidity (95-98%) to begin fruiting.  When small mushroom fruit bodies start to form (pinning) and grow larger, humidity can be decreased steadily until it's time to harvest.  Usually this is done one or two days before harvesting your mushrooms.  Harvesting at a lower humidity level (70-90%) helps mushrooms stay fresh longer in the refrigerator, they have better texture, and cook more easily.  Also, like temperature, many species prefer variations in humidity at different times.  Shiitake are known for this, preferring daily oscillations. 

Air exchange- C02 concentrations in your fruiting space will change the way your mushrooms look, and how much weight in mushrooms you can grow.  Again, this is species specific, so know your mushroom culture and adjust air exchanges accordingly.  For example, oyster mushrooms notoriously need more fresh air than most gourmet or medicinal species.  We exchange the air for our oyster mushrooms 8 times per hour to grow short stemmed and large capped oysters that are the desired form.  Try and keep your CO2 levels between 450 & 800 ppm for most mushroom species.

Light-  Light is necessary for growing the majority of gourmet and medicinal mushrooms species.  The exact light requirements are species specific.  Most mushrooms grow well with simple led rope lights that produce 6000k light.  Put your lights on a timer with at least several hours of light per day.   

Timing- Timing makes a big difference when fruiting your mushrooms.  Letting your colonized fruiting blocks sit too long can lead to drying out, decreasing your mushroom yields.  If you put them into your fruiting space too early, they will keep colonizing the substrate until full colonization takes place, before fruiting mushrooms.  This can lead to contamination, depending on your fruiting space and how much time it takes to colonize before fruiting begins.

Now that you have a space where you can control these factors, it’s time to fruit your mushrooms.  Put your fruiting blocks in the fruiting room and cut the plastic to expose the mushroom tissue to the humidity, fresh air, light, and the temperature of your fruiting space.  Allowing more of the fruiting block to be exposed, leads to more, but smaller mushrooms.  It can also lead to the fruiting substrate drying out too quickly.  Experiment with different shaped cuts and locations to determine what will work the best for your mushroom culture and fruiting room conditions.  A simple 5’’ x cut across the front of an oyster mushroom fruiting block usually does the trick. A diagonal 5’’ cut with a 2.5 inch cut going diagonally the other way from the top corner to the original cut (3/4 of an x cut) works very well too, and helps maintain humidity.

Store harvested mushrooms in a paper bag in the refrigerator.  You may be wondering how long will fresh mushrooms stay good in your refrigerator?  It's species specific, but generally you'll have a week or more to enjoy your mushrooms.

The Cloud Culture Monotub     

Growing mushrooms in monotubs is probably the least expensive option you can choose for growing indoors with great success.  They can save time and money, but become expensive if growing large amounts of mushrooms.  Most home hobby growers would be satisfied with 1 to 6 monotubs.  The monotub we’ll describe here can hold two 5 pound oyster mushroom blocks, which can potentially produce a couple pounds of fresh oyster mushrooms in 2 to 6 weeks.   Don’t feel obligated to grow oyster mushrooms, as monotubs work great for many different species of fungi.


  • Clear Plastic storage bin (66 qt/62 L).  Larger bins work well too.
  • Hole saw, 1.5 inches
  • Polyfill or 3M micropore™ tape (paper tape)
  • Perlite
  • Fluker’s Repta-clamp Lamp or similar light fixture
  • LED 6000K – 6500K light (60 watt equivalent) 
  • Light timer

Pick a storage bin that is clear (lid and bin), doesn’t have a gasket, and is large enough to provide space for your growing mushrooms.  Use the hole saw to cut 10 holes in the storage bin.  Cut 4 holes on the long sides (front and back), and one on each end.  The holes on the long sides of the tub should be cut so there are two holes that are 2 inches above the perlite spaced 5 inches in from the corner of the bin on both sides.  Also, there should be 2 holes spaced inward 5 inches from the corner of the bin and 3 inches below the top edge of the bin on both sides.  The short ends of the storage bin should each have one hole drilled directly in the center. 

Stuff each hole with polyfill or cover the holes with paper tape.  This will allow for gas exchange without letting in contamination.  Spray down the inside with 70% rubbing alcohol and wipe it out with a paper towel.  Make sure you get it really clean!  Add 3 inches of perlite to the bottom of your monotube.  Hydrate the perlite to carrying capacity and spray it with hydrogen peroxide to keep bacterial contamination at a minimum.  You want to hydrate the perlite so it’s 100% hydrated without letting very much water form a puddle on the bottom.  Puddles can harbor bacteria.  Ideally, after several hours you’ll see small droplets of water form on the inside surfaces of your monotube once it’s all set up.  If it’s so humid that you see drips of water falling from the lid, take the lid off once per day, hold the lid vertically, and let the excess water drain off into a separate container.  Do this each day until it stops dripping.

Here is the trick to keep contamination down and make an environment that your mushrooms will love.  Choose a light that will create some evaporation and make sure it’s spaced properly from the lid.  That’s the secret.  The monotub should have a dry spot directly under the light where the humidity has evaporated on the inside.  The dry spot indicates that the evaporation rate is right.  Positioning the light takes a little practice.  You’ll know that it’s too close if mushrooms won’t grow directly in the center of your monotub under the hottest part of the light.  Next time, move it up a little higher.  For reference, the light should be about 4-6 inches above the lid of the monotub to achieve proper evaporation with a 60 watt equivalent LED bulb.  Put your light on a timer set to 10 hours of light each day.

Put your fruiting container/block inside the monotube on top of the perlite.  Place your container/block so there will be room for your mushrooms to grow inside the tub without hitting the sides.  Expose some mycelium and be patient.  Cutting an x in the front or top of a fruiting block works well for exposing mycelium.   If using jars or trays, just remove their lids/covering inside the tub.  It can take 5 days to several weeks before your mushrooms start to fruit.  Put your monotub in a location with ambient light if you aren’t using a light on a timer.  Also, place your monotub where the temperature can be maintained within the ideal range for the species of fungi you’re growing.  Room temperature will work for several species of gourmet mushrooms.  Lion’ s mane works well in a monotube and good strains are very resistant to contamination.  Check out our Commercial Lion’s Mane Liquid Culture.

Outdated monotub directions often describe taking off the lid to mist and fan your mushrooms/substrate multiple times per day.  DO NOT TAKE OFF THE LID TO MIST AND FAN.  For many species, this isn’t necessary and will lead to contamination.  If you’ve done your prep work properly with lighting, humidity (perlite), temperature, and gas exchange, you will have a space that is perfect for growing mushrooms.  All you have to do is be patient and wait for them to grow.  Hydrated perlite will maintain the humidity for at least a month.  Depending on ambient conditions it may last much longer without needing to be replaced.

Keep an eye on the exposed portions of your fruiting substrate/mycelium.  Some species change colors a little as they mature, so know your mushrooms and don’t mistake this for contamination.  The two types of contamination you’re most likely to encounter are Trichoderma and bacteria.  Bacteria likes standing water and overly wet conditions, often causing the substrate/mycelium to appear brownish.  Trichoderma is a fungal parasite that is more prevalent during the summer or in warmer weather.  It looks white at first, but quickly turns green.  Contamination in general prefers warmer conditions, especially above 80° F.

Use sterile technique as much as possible while preparing your monotube for fruiting mushrooms.  To keep air contaminants at a minimum, spray a general disinfectant, such as Lysol® spray, into the air and let it settle for 5 minutes.  Also, turn off fans, your furnace, etc. so the air is calm in your work space.  Wear a face mask and keep hands clean with rubbing alcohol, or wear nitrile gloves sanitized with rubbing alcohol.  Also, wear a face mask.  These simple steps will help keep contamination at a minimum and boost your odds of success significantly.

Have fun with your monotub!  Try different species and enjoy the fruits of your labor.  Mushrooms grow quickly, are fascinating to watch, taste delicious, and are incredibly healthy.

Pictured is a Reishi experiment in a tall monotub, with a 600K rope light, and paper tape over the air exchange holes.  There are 5 x 5 reishi blocks that are top fruiting beautiful antlers.

Did you like this article?  Share it on your favorite social media and help support Cloud Culture Mushrooms.   Want to try growing mushrooms?  Try growing lion’s mane!  Lion’s mane is very hardy and resistant to contaminants.  Plus, they are delicious and healthy!  Click here to buy commercial lion’s mane liquid culture.   Need mushroom grow bags?  Check out our supply!

Enjoy, and “always grow culture.”  


Considerations for Specific Species

Shiitake- Shiitake mushrooms require a unique procedure and fruiting substrate compared to other gourmet mushroom species.  Many strains of shiitake prefer oak sawdust and won’t fruit on other hardwoods.  Also, Shiitake mushrooms are best grown on logs or blocks made in poly bags.  They take 8 to 12 weeks to fully colonize, popcorn, and brown or blister all over when growing them in poly bags.  Make sure your colonizing shiitake blocks have some ambient light on all sides to mature properly.  When the block if fully brown, you need to soak it and slap it.  Yes, folks.  It’s weird, but here is what’s going on.  Long colonizing blocks, such as shiitake, loose moisture through the filter patch over time.  Soaking the block replenishes its moisture and the cold of the water triggers the mushroom to think it’s fall or springtime.  Make sure you use non chlorinated water to soak your shiitake logs.  Use your hand to smack each surface of the block hard enough to give it a good thump, but not so hard that you crack through the whole block.  After that, all you need is a very high humidity space, with a little fresh air flow and some light, to stimulate your mushrooms to grow.  In about 5 days your blocks will begin to pin and within a week you should have full grown mushrooms to harvest.  Lower the humidity as the mushrooms start to grow, and even more during the last 12 hrs. prior to harvesting.  Harvesting shiitake involves cutting the mushrooms off individually as close to the block as you can without damaging it.  It’s possible to get multiple flushes from shiitake blocks, but you’ll get diminishing returns on your effort.  That said; a second flush is worth it, so put your harvested blocks in a cool dry space for 8 to 10 days.  During this time, flip them once or twice so moisture doesn’t get trapped below the block which can cause contamination to flourish.  On the last day of your resting period, soak your shiitake blocks in distilled water or chlorine free water for 24 to 36 hrs.  Remove the blocks and rinse them off with clean water, smack them on every surface and put them back in your fruiting space.  Five days later you’ll have pins, with mushrooms maturing over the next week.

Lastly, enjoy your shiitake mushrooms.  They are absolutely delicious and a favorite of many.

Reishi-  One way reishi is consumed is by breaking up the fruiting body and simmering it for 1 to 2 hours to make a hot water extract tea.  Filter out the solids from the tea and it’s ready to go.  Reishi tea is bitter and not generally consumed for its flavor, but rather for its medicinal qualities.  Reishi grows well on masters mix.  We recommend giving your fully colonized reishi blocks some light each day so it will start to fruit in the container.  Keep your fruiting container sealed (except for the filter patch) until the red shiny fruit bodies start to form.  This also helps prevent contamination.  Depending on cultivation methods, fruiting can take several months from beginning to end, once the mushrooms begin to grow.  Harvest reishi close to the substrate using a seriated knife to saw them off.  Use fresh reishi within a couple of weeks or dry it in a dehydrator at 95° F for 48 to 96 hrs.  The red shine will turn to a mat red color when it is dried completely. 

Oyster Mushrooms- This is a big category to cover due to the number of oyster mushroom strains that have varying characteristics, so we’ll cover some generalities.  First, oyster mushrooms are fast colonizing and fruiting.  They require relatively high humidity (95-98%) to begin fruiting, but this can be lowered as the mushrooms grow, to 88-94%.  Decreasing the humidity 12 hrs. prior to harvesting, increases the shelf life of your oyster mushrooms, and improves their texture.  Oyster mushrooms are one of the heaviest spore producers of any of the gourmet and medicinal mushroom species.  Harvest your oysters before cap edges invert to form a cup.  Generally, the younger you harvest your oyster mushrooms, the longer the shelf life will be.  Also, if you harvest your oyster mushrooms before they begin to spore heavily, you’ll keep your fruiting space cleaner.  Make sure your fruiting space has plenty of air exchanges per hour to get the ideal oyster mushroom fruit body; typically around 500 ppm of CO2.  Make sure to vent your heavy C02 spore laden air outside to prevent breathing in excess mushroom spores.  In high CO2 environments oyster mushrooms become “leggy,” growing long stems and tiny caps. The caps are the most sought-after part of the mushroom, so keeping CO2 levels below 600 ppm will greatly increase the size of your caps.

Lion’s Mane- This mushroom is not what people think when they hear the word mushroom.  It appears as one or several white balls stuck together, which expand and eventually form shaggy looking “teeth.”  Teeth formation, along with possible browning on the top and base of the mushroom, signal that it is mature and ready to be harvested.  For best taste, try to harvest it before any browning occurs.  These mushrooms fruit easily and can do so in a wide range of humidity and temperature levels.  They are also the most contamination resistant of all the gourmet and medicinal species we’ve grown.

Chestnut- Chestnut mushrooms require patience and a clean fruiting space.  They are more prone to contamination than other gourmet mushroom species.  They also grow slowly.  They can take 2 weeks or more to completely form mature mushrooms from the onset of pins, depending on variables. That said, they are absolutely beautiful and taste fantastic.  Chestnut mushrooms also maintain their form through the cooking process and even keep a little crunch which is pretty unique.  Also, note that the substrate turns a bit orange as it matures and starts to begin to fruit; don’t mistake the color change for contamination.  

Cordyceps militaris-  This awesome looking club-shaped mushroom is highly medicinal.  Fresh fruit bodies can be cooked like regular mushrooms and added to dishes for increased health benefits.  Freshly fried cordyceps has almost no flavor, so add spices to your preference.  Fresh or dried cordyceps (dehydrator for 48 hrs. at 95 F) has a strong generic mushroom flavor when prepared as a tea.  To make tea, simmer fresh or dried fruit bodies for 1 to 2 hrs., or until the orange is bleached out of the mushroom.  This mushroom fruits directly from grain in its original container.  Cordyceps mycelium requires complete darkness while colonizing substrate before fruiting.  Once it is fully colonized, (approximately 3 weeks) place the fruiting container in indirect sunlight to initiate fruiting.  Keep your cordyceps between 60° and 70° F for colonizing and fruiting. In 4 weeks the substrate/mycelium will begin to turn orange and fruit.  They take a while to go through the fruiting process, so be patient and you will be rewarded with this wonderful mushroom.