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The Cloud Culture Monotub (a low Tek method for growing 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 6-pound mushroom blocks, which can potentially produce three pounds of fresh mushrooms in 2 to 6 weeks.  Monotubs work great for growing many different species of fungi.  We reccomend starting with a mushroom species that is eager to fruit such as blue oyster mushrooms or lion's mane mushrooms.


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)


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.  Hydrate the perlite so it’s 100% hydrated without letting very much water form a puddle on the bottom, because puddles can harbor bacteria which can lead to contamination.  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 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.  The combination of light, humidity, and evaporation will tell your mushrooms that its time to start fruiting.

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 is generally 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 a shade orange, red, or brown.  Trichoderma is a fungus that is also a fungal parasite that is most prevalent during the summer or in warmer weather.  It looks white at first, but quickly turns green.  Trichoderma can get out of control fast, so try to prevent it from entering your monotub by using your best sterile practices.  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.

Click here to learn more about growing mushrooms!

Enjoy, and “always grow culture.”  

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 lb. reishi blocks that are top fruiting beautiful antlers.



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