Monotub Protocol for Royal Flush Monotub Mix


The Monotub

Purchase the monotub of your choice, any large, clear tote container will do. Ensure that you also purchase a lid.

Your mushrooms need to breathe so it is necessary to drill holes in the monotub. The diameter of the holes should be about 5cm. These holes should be above the level your bulk substrate will come to. Using a drill bit that is modified for making holes, drill a hole every 20cm along the side and ensure there is a hole on each end.   

Now that you have done all that difficult drilling it is time to fill in all the holes you just made! Use polyfill to stuff the holes. This will act as a filter allowing air to flow through but limiting the number of particles floating in. Tape in place if necessary. 

Some growers opt to paint the bottom half of their monotub or line it with a black garbage bag. This is a measure to prevent side pinning, as light is a trigger for the direction that the mushrooms grow.. Side pinning is not detrimental; it is simply mushrooms that are growing at the side of the bulk substrate. These pins use up nutrient resources and are often difficult to harvest. 

Grain Spawn 

Colonized grain spawn is necessary for monotub inoculations. You want to ensure that the mycelium (‘mushroom roots’) have covered the sterilized grain before inoculating. When the bag is fully covered in white you can consider the spawn fully colonized.

Remember that like people not all mushrooms like to eat the same things. Wood-loving fungi, such as oyster mushrooms need to be inoculated in a hardwood sawdust fruiting block. The Royal Flush bags will work only for dung-loving fungi. 

If you plan on growing a manure-loving species that does not have commercially available spawn you can create your own by purchasing FORIJ Grow Master Sterile Grain. This product comes with an inoculation port for liquid culture. You will also need to purchase genetics in the form of liquid culture or mycelium on a Petri dish to inoculate your Grow Master bag. 


THIS STEP IS CRUCIAL. Before you inoculate your monotub you want to make certain that everything that will be in proximity to your grain spawn and substrate is clean.

Make sure to wear disposable gloves. Spray and wipe everything down with isopropyl alcohol. This includes your work surface, the inside and outside of your monotub, the monotub lid, the outsides of your spawn and Royal Flush bags, and the scissors you use to cut open your substrate. Ensure you spray your gloved hands before cutting open the bags.


We recommend a 1:2 or 1:3 ratio of  grain spawn to Royal Flush Monotub Mix ratio. Two bags of 3.5lb of monotub mix should be enough to inoculate a moderately sized monotub. 

Using gloved hands, first squeeze a fistful of the Royal Flush mix as hard as you can to check that it’s at field capacity. You want a small tiny stream of water trickling down your hand when you squeeze. Spray the substrate with tap water if it’s not quite there yet. Then, break up your grain spawn bag by massaging the bag so that the grains are loose and can be easily distributed in your tub. 

With scissors, cut open your Royal Flush and Grow Master bags. Begin to layer your monotub: add an approximately 3 cm layer of Royal Flush monotub mix into your monotub covering the entire bottom. Then, sprinkle a thin layer of  grain spawn all over the first layer. Repeat laying your substrates in a lasagne-like pattern until you have reached your desired height and finished off both bags. Make sure you end with a layer of Royal Flush substrate mix encasing all of your grains. Do not leave any grains exposed--grains are extremely nutrient dense and pose a threat for contamination. 

Once you have filled your tub, put the lid on and do not take it off until your substrate is fully colonized, this should take about 1-3 weeks.

Place your tub somewhere at room temperature and away from direct sunlight, but with indirect lighting in natural cycles. 

Mushroom Care 

Your substrate should take about 1-3 weeks to colonize. You will be able to tell your tub is fully colonized because it will be coated in a layer of white mycelium. Look for signs of pinning. Once you see pins (mini mushroom stubs) it is now safe to remove the lid to mist and fan your tub 2-3 times a day. 

At this point, you should take 2-3 times out of your day to fan and mist your tub. Take the lid off and with gloved hands, fan your tub for approximately 1 minute. Then, mist the mushrooms with a spray bottle of tap water until the top layer of substrate is moist and you can see beads of moisture on the side walls of your tub. Put the lid back on, and repeat this another one two two times throughout your day. After you see pins, your mushrooms should take anywhere between two to seven days to fully mature. 


Your mushrooms are ready to harvest when the caps have just started to open up and the veil is about to break. Make sure you harvest your mushrooms prior to this veil breaking, or you risk the mushroom sporulating (spreading its spores) onto the substrate. When this happens, your monotub might have trouble having future flushes, so make sure you harvest earlier to to maximize yield.

You can harvest your mushrooms by slicing the bottoms of the stems with a knife, or taking a gloved hand and twisting and pulling the bottom of the mushroom stalk. We prefer the twist and pull method, but if you have several monotubs going at once cutting might work for efficiency. 

Even as you’re harvesting, continue to maintain your monotub by fanning and misting. Your tub will continue to produce several flushes--somewhere between two to four flushes. 

When your substrate is completely “spent”--that is, when the flushes are now too small and not yielding many mushrooms at all anymore, you can recycle the spent substrate by crumpling and burying the myceliated soil in your garden. The mycelium helps your roots retain moisture, so your plants and veggie gardens can grow bigger and healthier. 

Drying and storing

You can prolong your mushrooms’ shelf life by refrigerating or drying your mushrooms. We recommend you dry your mushrooms with a commercial food dehydrator, which can be easily purchased at a local Walmart. Dry your mushrooms at the lowest setting over a longer period of time to preserve all the nutrients in the fruiting body. You can then bag up the dried mushrooms and enjoy your mushrooms over a longer period of time!