Myterra Tek: Grow King Oysters in a Monotub

If you're looking to maximize your King Oyster mushroom yields, then you are going to want to try out our new tek: the Myterra Tek.

Growing King Oyster mushrooms in a bag can be tricky and provide inconsistent yields. That's why we have worked so hard to established a tested protocol for growing King Oyster Mushrooms in a monotub so that you can grow these mushrooms with ease. Even better, you can grow King Oyster Mushrooms in your home!

You'll be surprised to find that there are very few steps to growing these mushrooms. We utilize Max Yield Bins as our fruiting chamber of choice because of it's set-and-forget style of growing, but you can use this method in any monotub as long as you keep the ratios of substrate:grain in the same proportions. 

The entire process from inoculation of grain to first harvest takes ~6-7 weeks. The hardest part of this process is having patience. Keep focused on your goals of having a bin full of king oyster mushrooms and you will be greatly rewarded.


Are you as excited as we are? Then let's get started!



What Do I Need to Grow King Oysters in a Monotub?


We have everything you need to grow King Oysters in a monotub - click on the items in bold to easily find each item in our store:


Step 1: Make Grain Spawn


The first step to making grain spawn is to inoculate your grains. Inoculation is simply adding your culture into a new medium/substrate. In this case, you are going to be adding your liquid culture to your grains. The grains will become colonized by the mushroom mycelium and the final result will be your grain spawn.

Luckily, this process can be done in a non-sterile environment - how easy is that!


1. Attach the needle to the syringe without letting the tip of the syringe or needle touch anything. Keep the needle capped and perform this process as quickly as possible to minimize the risk of contamination.

2. Open the external packaging of your grain bag and remove the clear plastic bag (unicorn bag). Spray the front of the bag with isopropyl alcohol over the area that contains grains.

3. Attach the injection port (included with the grain bag) to the front of the bag over the top portion of the grains. Spray the injection port with isopropyl alcohol after sticking it onto the bag.

4. Uncap the needle and stick the needle directly into the injection port until the needle is completely inside the bag. Inject all of the culture into the bag while moving the needle from side-to-side to spread the culture around the grains. Remove the needle, cap it, and properly dispose of the needle and syringe.

5. Place the grains on a shelf in your house at room temperature for 2-3 weeks. Grains can be placed in a light or dark area, but not in direct sunlight.

6. The grains will begin to turn white over the next few days. Shake your grain bag after 1 week to spread the mushroom culture (the white bits) throughout the bag. This will speed up the process of colonization until all of your grains are white.

Well Done! You officially have grain spawn.


Step 2: Mixing Grain Spawn and Woodlovers


This can be quite a fun process, but you will need to either work in front of a laminar flow hood, in a Noc Box, or in a clean room that does not have access to pets and has minimal air flow. If your pets have access to all rooms, clean all surfaces in the room, and close off the room for 24 hours with the windows shut before you attempt this step.

Tape the holes of your monotub with a layer of micropore tape, then place a layer of painter's tape over the micropore tape. You will be removing layers of tape at a later stage to slowly introduce air into the monotub.

Place your alcohol spray bottle in the room, as well as some paper towels, a clean knife/scissors, clean monotub, spawn bag and Woodlovers bags. Gloves are recommended, but are not necessary.

During the mixing process, you should wear clean clothes, have hair tied back, and have clean hands.


1. Shake your spawn bag to loosen the grains and break any clumps of grains.

2. Spray the inside of your monotub and the handles with alcohol and wipe all surfaces with a paper towel. Close the lid until step 4.

3. Spray the work surface with alcohol and wipe with paper towel.

4. Open the external packaging of your Woodlover bags and remove the clear plastic bags (unicorn bag). Spray your spawn and Woodlovers bags with alcohol and wipe the alcohol over every surface of the bag. 

5. Spray your knife/scissors with alcohol and cut off the top of your Woodlover bags, one at a time, and pour all of the contents into your monotub.

4. Spray your knife/scissors with alcohol again and cut off the top of your spawn bag. Hold the lower quarter of you bag to reserve it for later and pour the top 3/4 of the spawn into the monotub. If you do not have a laminar flow hood or Noc Box, close the bin lid and fold the top of the bag over to close the bag during the next step. 

5. Spray your hands/gloves with alcohol and rub the alcohol over all surfaces of your hands. Allow to air dry.

6. Mix the grain spawn and Woodlovers in the monotub as evenly and as quickly as you can. Make sure the surface of your mixture is even and smooth.

7. Sprinkle the reserved grain spawn evenly over the top of your mixture. Lightly press the grains into your mixture. Close the lid of your monotub.

The grain spawn on the top of your mixture will deter any contaminants from infecting your monotub mixture.

8. Place the monotub in a room temperature or cooler environment for about 1 week. Do not place in a room that is cooler than 40F or warmer than 75F. Wait until all of the Woodlovers mixture has turned white.

You've completed the most intricate step of this entire process! Give yourself a pat on the back and sit back as your mushrooms enjoy their new food source.



Step 3: Add a Casing Layer


 Once your King Oyster bin is fully colonized, it's time to add a casing layer.

This step needs to be performed in front of a laminar flow hood, in a Noc Box, or in a clean room that does not have access to pets and has minimal air flow. If your pets have access to all rooms, clean all surfaces in the room, and close off the room for 24 hours with the windows shut before you attempt this step.


1. Spray the outside of the bag with 70% isopropyl alcohol and wipe the alcohol over all surfaces of the bag using paper towel.

2. Spray your scissors/knife with alcohol. Spray your hands with alcohol and rub the alcohol over all surfaces of your hand and allow to air dry.

3. Shake your M-minus bag to loosen the substrate and break up any clumps.

4. Pour M-minus over the surface of the colonized bin - as shown in the video. You will only need 1/4-1/2 of a bag of M-minus. Make sure that the casing layer is evenly spread across the surface. You can use your clean hands to sprinkle substrate into the corners of the bin.

5. Close the lid of the bin and remove the painters tape. Wait for ~1 week for the surface to become colonized (fully white with mushroom mycelium).


Step 4: Fruiting King Oyster Mushrooms


This is probably the most exciting phase. You'll be watching as the white mycelium changes, knots together and forms tiny little lumps on the surface. Next thing you know, your bin will have identifiable mushrooms on the surface. This process will take ~1 week, but you will be able to see some big changes happen each day.


1. As soon as the black M- casing layer has turned completely white (AKA it is fully colonized), take the micropore tape off of the holes in your bin lid and base. This will introduce air into your monotub and trigger pin formation. Mushroom pins are the early stages of mushroom development and look like tiny little white blobs/towers. Place the bin in a humidified tent/room.

2. The pins will start to develop caps which are a slightly darker color to the pins. When your little mushrooms grow to about 1/2" in height, remove the lid of the bin. Removing the lid of the bin can cause the mushrooms to dry out so it is best to have a little patience. 

The video below shows young king oyster mushrooms in a monotub, ready to have the lid removed.


Step 5: Harvesting King Oyster Mushrooms


You've made it to the final goal and your mushrooms are looking great! Now, the panic sets in as you start to worry about the ideal time to harvest your mushrooms. Don't worry, we're here to teach you a valuable skill that can be used when growing any oyster mushroom.


Have a look at the cap of the mushroom. Notice how the edges are curled inwards towards the stem? As the mushroom grows and ages, the edges of the cap will start to uncurl. If you were to leave the mushroom for a long enough time, the cap would also become inverted. When the edges of the cap are uncurled and the cap starts to invert, the mushroom will start to release spores. Oyster mushrooms are known for their prolific spore production, meaning that these mushrooms can fill a room with spores and leave all surfaces with a white layers of spores if you're not careful. Spores can also irritate the lungs and prolonged exposure to spores can be very harmful to your airways, in some cases causing irreparable damage. 

 So, in order to avoid spore release by your mushrooms, always harvest before the cap is fully uncurled. Below is a video of King Oyster Mushrooms Grown in a Max Yield Bin and ready for harvest.


1. Harvest your mushrooms with a small pair of sheers, or a knife, or you can twist and pull them out of the substrate. Harvest all mushrooms in the monotub within 2 days. Make sure to remove all of the small mushrooms that are starting to turn soft or are drying out - these are called aborts. 

2. Once you have cleared all of the harvestable mushrooms, add 1 cup of water down the side of the monotub, between the monotub and the substrate. This will rehydrate the substrate and provide much needed moisture for your next harvest (flush) of mushrooms.

3. Place the lid back on the monotub and tape over the holes with micropore tape again. Within a week you will start to see your next harvest of mushrooms growing again. Remove the micropore tape when new mushrooms are visibly growing and remove the lid when the mushrooms are 1/2" tall.


Congratulations! Get your frying pan ready, you now have a delicious gourmet mushroom to add to your meals. Store any unused mushrooms in the fridge in a paper bag or cardboard box for up to 1 week.


Let us know how you did - tag us on social media or send us an email ( We are always happy to see more mushrooms growers succeed and we are always here to help along the way.