King Oyster Mushroom Kit Instructions

King Oyster mushroom is a delicious, meaty mushroom that is native to the mediterranean and popular in Asian cooking! King oyster mushrooms form large beautiful 'trumpets' that will grow inside the fruiting bag which is fitted with a special micro-filter patch, allowing some gas exchange but inhibiting moisture loss and competing organisms.

Each species of mushroom is a different growing experience. Even if you have grown mushrooms before, please read the instructions for your kit carefully before proceeding. If you run into any problems please see our FAQ.

Step 1: Mycelium Check

Inside this box mycelium has has been happily breaking down the organic growing medium and converting it into energy. At first the mycelium is often wispy and hard to see, but as it gets ready to produce mushrooms it becomes more dense and white in colour.

Open the box and remove the bagged block of mycelium and growing medium.

Brown or Brown & White =

needs more time in a warm location

Mostly White =

ready to move on to stage 2

Entirely White =

ready to move on to stage 2

If your block is brown, unroll the bag and move your block to a dark location - over 15°C and NO MORE THAN 25°C. Check it once a week until at least 60% of block is covered with white mycelium.

If your block is covered with over 60% white mycelium you can now move on to step 2. If you do not want to move on to step 2 at this time, you can keep your kit in the fridge or a cool place for up to two weeks.

Step 2: Finding and creating ideal conditions

King oyster mushrooms grow best when they are out of direct sunlight and have plenty of humidity and some fresh air exchange. Finding and/or creating the perfect environment is key to getting the most mushrooms out of your kit.

Find a place in your house that it out of direct sunlight. If you've purchased a thermometer/hygrometer, a temperature reading between 12°C and 17°C is ideal.

Do not enclose in a box or cupboard as oysters need access to fresh air or they will not grow properly.

Your mycelium block comes in a grow bag with a breathable micropore filter patch to help facilitate gas exchange. You will grow your mushrooms inside of this bag to help keep humidity up and pests and competing organisms out.

Step 3: Initiating Fruiting

You can choose to fruit your king oyster kit in one of two ways depending on your personal preference and your environment:

Side Cut Method: Make a cut along the side of the bag. This method yields more, but smaller-sized mushrooms and is easier to keep the block from drying out.
Open Top Method: Open the top of the grow bag. This typically produces fewer but larger mushrooms. However, this method requires higher maintenance and requires precise timing - you’ll need to keep up with regular misting as the block dries out more quickly and you’ll also need to keep a close eye on your kit so that you can open the bag at the right time, otherwise the mushrooms will not grow properly (as outlined below).

Option 1: Side Cut Method

Make a large ‘X’ shaped cut in the side of the bag, then flip the block on its side so that the cut is on the top (as pictured below).

If using this method, do not cut away the plastic, as this will dry out the block and hinder mushroom growth.

Note the size of the cross. The block will need to be flipped on its side so that the cut is facing upwards, as the mushrooms will grow upright from this opening.

Option 2: Open Top Method

Cut open the grow bag along the top edge.

Create enough room for your mushrooms to grow inside the bag.

Roll the top of the bag down twice and seal with clips (pictured below).

Step 4: Misting & Fresh Air Exchange

King Oyster Mushrooms prefer to grow in an environment with 80-90% humidity. Because of this, you'll need to gently mist your kit regularly with a clean spray bottle. You want to create a humid environment for the mushrooms and to keep their bodies moist.

However, they also require access to oxygen and fresh air exchange to grow properly. If you are starting off your mushrooms inside of the growing bag, you will need to add some fresh air to your kit regularly.

For the Side Cut Method:

Mist the opening you've cut in the bag 1-2 times daily and keep a close eye on it. As soon as you spot the first signs of the mushrooms pinning, increase the misting to 2-4 times a day to keep the growing mushrooms from drying out.

For the Open Top Method:

Once per day, open the top of the bag and spray generously and fan in fresh air for 1 minute.

Keep a close eye on the top of the substrate. As soon as your mushrooms begin to pin, you will want to move on to Step 5.

Step 5: Pinning and Increasing Fresh Air Exchange (for Open Top Method)

These additional steps are only necessary for the open top fruiting method. If you are fruiting from slits in the side, there is no need to do anything further to increase fresh air exchange.

For the open top fruiting method:

As soon as you see pins starting to form on the surface of your substrate, you will need to increase the fresh air exchange by rolling down the top of you bag like the photo below.

Increase your misting to at least twice a day (you may need to do so more frequently depending on your environment), making sure the keep the fruit bodies moist by misting very generously.
Once fresh air exchange has increased, pinning should develop rapidly. Please note that not all pins will develop into full grown mushrooms, but this is normal and expected.

King Oyster pins forming on the surface of the block.

Open top method with the sides of the bag rolled down.

King oyster mushrooms growing in the open top method (left) and the side cut method (right).

'Pinning' should begin within 5 weeks of initiating fruiting. If you haven't seen any pinning after 5 weeks please see our FAQ. Once they have begun to pin, your mushrooms will grow rapidly. Keep the mushrooms moist during this period.

Step 6: Harvest

Harvest your mushrooms before the edges of the caps begin to either flip up or to wrinkle, darken and split. A white dust under your mushrooms means they have started to drop spores.

Your mushrooms will be at their most tender if you harvest them before they drop spores, but they'll still be perfectly delicious if you don't quite catch them in time.

When your mushrooms reach the desired size, harvest them by twisting and pulling each one off at the base. Avoid cutting, as leaving the stem attached to the growing medium can hinder mycelium growth and encourage mold. Make sure to harvest all mushrooms, including any small pins, from the first flush before attempting a second, as leftover mushrooms can inhibit new growth.

Step 7: Initiating The Next Flush

King oyster mushrooms will generally yield 1-2 flushes. To attempt a second flush of mushrooms try the following:

Make sure you have harvested all mushrooms and removed any fruiting body remnants.

Fill your growing bag with enough tap water to cover your block and store your block in the fridge for 12-24 hours.

Drain away excess water, clip the top of the bag closed again, and resume from step 4.

Step 8: What to do with your kit when it stops producing mushrooms

Did you know that fungi play a key role in storing carbon? Trees and plants remove carbon from the atmosphere and fungi break down plant waste to create new carbon-rich soil. Clean air, healthy soil and delicious mushrooms: just one of the many ways fungi are incredible!

Once your box has finished flushing, open the box and remove the mycelium block from its plastic bag. Discard the bag in the general waste. You can now recycle the box and additional packaging and compost the block. Alternately plant it in the garden to see if it will gain a some energy and produce one last seasonal crop for you! Simply dig a hole in a shady spot, bury the block and cover it over with around 5cm of soil. Water it occasionally to keep the soil moist.

We hope you've enjoyed growing your King Oyster mushrooms!

We're passionate about sharing the diversity of the fungi kingdom & making more of its delights easy to grow. Want to try another strain or learn how to cultivate mushrooms? See our full range of mushroom growing kits and cultivation workshops!

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