King Oyster Mushroom
Grain Spawn

Pleurotus Eryngii

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King Oyster Mushroom Grain Spawn

Grain spawn is a little known secret weapon of the world of mushroom cultivation. It’s made from sterilised grains that have been inoculated with a live mycelium culture.

Grain spawn contains a lot of energy for the mycelium to consume. It’s a bit like rocket fuel for mushrooms. Once it’s added to your substrate it takes off like wild fire. 

Mother Nature works her magic using spores but in a controlled environment you need to tip the scales in your favour by using clean high-quality grain spawn so you are doing your best to ensure success. 


Our products are produced freshly for maximum vigour. At time delays of 14 – 21 days may occur due to increased demand. All orders are dispatched between Monday – Wednesday via Australia Post Express Post to ensure same week delivery.

What Are King Oyster Mushrooms?

The king oyster or trumpet mushroom belongs to the oyster mushroom genus, pleurotus. It’s the largest oyster mushroom featuring a thick and meaty stem (stipe) which has resulted in it being valued for culinary purposes around the world.

The king oyster is purposefully grown with elevated levels of CO2 to encourage the typical king oyster shape with a large stem and small cap.

The king oyster is a ‘top-fruiting’ species as opposed to the pink, white and yellow oyster species which fruit well from the side. 


What Do King Oyster Mushrooms Taste Like?

King oyster mushrooms are thick and meaty with a mild mushroom flavour which sweetens upon cooking. It holds together well during cooking and if often used as a substitute for scallops or other mild flavour meats.

King oyster mushrooms are some of my favourite for cooking with. Either fried, grilled or even in soups. You haven’t lived until you’ve tried some crumbed king oyster mushrooms. 

What Do King Oyster Mushrooms Grow On?

King oyster mushrooms are often found growing wild on dead and decaying hardwood. However, unlike the other oyster species P. eryngii can be mildly parasitic of the roots of herbaceus plants.

In terms of mushroom cultivation the king oyster mushroom can be cultivated on cellulose rich substrates like sugar cane mulch, straw and corn cob however it will perform better yielding more and higher quality fruits when grown on hardwood or a supplemented hardwood mix like masters’ mix.

It can be grown in outdoor garden beds, monotubs or mushroom grow bags during the cooler months of the year.

Learn How To Grow Oyster Mushrooms

Growing oyster mushrooms in buckets is a great project for first timers and more experienced cultivators alike. You can grow your own mushrooms at home using sugar cane mulch, straw or the cellulose rich material of your choice in conjunction with either cold or hot water pasteurisation.

Simple and easy to do using a few household items.

How To Grow King Oyster Mushrooms In A Monotub (Coming Soon)

Growing Mushrooms Outdoors

King oyster mushrooms are the perfect candidate to be grown in an outdoor garden bed due to their preference for top-fruiting.

It’s crucial to cultivate mushrooms in  a location which will remain humid or receive regular attention to ensure the healthy development of mycelium within the substrate.

Learn More About Growing Mushrooms Outdoors (Coming Soon)

What Is A Casing Layer?

A casing layer is applied to the fully colonised surface of some mushroom species to increase humidity, improve yield and quality of the fruiting bodies.

When cultivating king oyster mushrooms a casing layer is completely optional. There is a slight risk of contamination when applying a casing layer. As an alternative we recommend to lightly scratch the top surface of the grow kit. Without opening the bag use your fingers or the handle of a spoon to scratch against the surface. This will create indentations which will generate the ideal conditions for the formation of king oyster mushroom primordia (pins).

For those who wish to apply a casing layer we recommend to use a mixture of 50% coco-coir and 50% vermiculite with 1% hydrated lime which is rehydrated with boiling water. Once cooled to room temperature a layer can be applied to the fully colonised surface of the substrate. 

Using A Humidifier

Humidity can be managed through a diligent misting and fanning regime, however the introduction of a humidifier and humidity controller can help automate the process and ensure consistency.

Adding a 6L humidifier and controller to a greenhouse with the addition of a USB fan is a quick and easy way to make a low cost fruiting chamber that delivers excellent results.

SGFC Shotgun Fruiting Chamber

Making A Fruiting Chamber

Mushrooms require humidity to grow. We recommend using a mini-greenhouse. Spraying the inside walls of the greenhouse will help raise humidity. A cheap humidifier can be used to automate the process.

It’s important to ensure that the grow kit has fresh air exchange. Mushrooms produce carbon dioxide and will grow long and leggy in search of more oxygen. 

Check the product pages for species specific requirements.

Alternatively you can build a Shotgun Fruiting Chamber (SGFC) from a few common items found easily in your local hardware store.

King Oyster Mushroom Spawn Run

King oyster mushrooms are very vigorous. Full colonisation can often expected within 10 – 14 days. Store at temperature between 20 – 26 degrees Celsius (68 – 78f) for optimum colonisation speeds.

King Oyster Mushroom
Pinning Conditions

Keep at temperatures below 15 degrees Celsius (60f) to trigger pinning. High levels of humidity of 90 – 95%RH with slightly increased fresh air for the development of primordia.

Only the top of the grow bag needs to be removed if using a mushroom grow bag. The higher sides will allow for CO2 to pool and develop thicker fruiting bodies with small caps.

King Oyster Mushroom Fruiting Conditions

Maintain the mushrooms at temperatures between 15 – 20 degrees Celsius (59 – 68f) for fruiting body development. Humidity may be lowered but should remain above 80%RH

Watch Our King Oyster Grow Guide (Coming Soon)

King Oyster Mushroom Grow Kits

Learn to grow your own mushrooms with one of our ready to fruit mushroom grow kits. 

Our kits consist of supplement hardwood which has been inoculated under laboratory conditions with a live mycelium culture.

Learn more about using a mushroom grow kit with our Step By Step Guide.


Our products are produced freshly for maximum vigour. At time delays of 14 – 21 days may occur due to increased demand. All orders are dispatched between Monday – Wednesday via Australia Post Express Post to ensure same week delivery.

Make Spawn With Sterilised Grain Bags

Each sterilised grain spawn bag has been carefully prepared by hydrating whole oats in a gypsum bath for 24 hours before sterilisation. 

The bag itself features a 0.2 micron filter patch to facilitate fresh air exchange without the contents becoming contaminated. 

Additionally, the self healing injection port allows the user to simply inoculate the grain using a liquid culture syringe with minimal risk of contamination.

Sterilised grain spawn bags make it possible to produce your own mushroom grain spawn without the use of a pressure cooker.

Who We Are

I’m Luke and I’m mad about mushrooms. I operate a small scale family run business located 40 minutes west of Brisbane. We’re passionate about fungi and we look forwarding to sharing our experiences with you.

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Frequently Asked Questions

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