Growing King Oyster

Pleurotus Eryngii

Free Shipping On All Orders

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 Substrate Does King Oyster 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.

Buy 10 Grow Bags For $10

Save on filter patch grow bags when you spend over $45 on grain spawn or grow kits. 

Opening A King Oyster Grow Kit

A different approach can be taken when opening a king oyster mushroom grow kit or fruiting block. Due to the top-fruiting nature of this species, the top can of the bag can be removed without need to fold back the plastic bag. This will create a reservoir which will retain CO2.

This species will produce thick meaty stems when grown in higher levels of CO2. The bag can be kept sealed until pins begin forming, making it one of the easiest mushrooms to fruit.

King oyster grow kit with casing layer applied.
King oyster grow kit with top removed.
King oysters growing through option casing layer.

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. 

Free Delivery With Every Order

Free standard delivery is included with every order. All deliveries are lodged via Australia Post.

Products listed available and in stock will be dispatched within 48 hours.

Flat rate express delivery is available with next day dispatch for any order placed before midnight 12 am.

Express post is recommended for placing interstate orders during the summer months to avoid delay and ensure freshness.

Back order – Any items on back order will be dispatched separately. Items on back order are anticipated to be fulfilled within 21 days unless stated otherwise.

King Oyster Mycelium Appearance

King oyster mushroom mycelium is similar in appearance and structure to white oyster mushroom mycelium. The strands of hyphal threads will grow vigorously creating  a thick, dense mat of mycelium if left undisturbed.

Like most species the mycelium will be noticeably less visible after agitation however the grain spawn will remain viable and ready for use.

Thick, dense king oyster mycelium on hardwood substrate.
King oyster mycelium is less visible after agitation but remains viable.

Learn How To Make Grain Spawn

Experienced mushroom cultivators will often produce their own grain spawn to reduce the cost of growing mushrooms. Grain spawn can be produced in small batches without the need for purchasing expensive equipment. Learn more about making grain spawn in our guide.

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.

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 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 if they require 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 Spawn Run

Despite king oyster mushrooms being vigorous, they can be expected to take an additional 1 – 2 weeks after colonisation to prepare for fruiting.

King Oyster Pinning Conditions

The bag may be kept closed until primordia has formed. This will ensure that the substrate remains in a high humidity environment which often results in the largest pin sets.

Keep at temperatures below 15 degrees Celsius (60f) to trigger pinning. Keep humidity over 80% with slightly increased fresh air for the development of primordia.

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

Sometimes primordia will form in the humid space between the bag and the grow kit. Taping the sides of the bag firmly to reduce air movement around the base of the block will reduce the formation of undesired primordia. Alternatively, a cut can be made to release these pins to complete growth.

King Oyster 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.

Excessively high humidity will often result in the mushrooms developing growths or deformations on top of the caps. These growths are an extension of the mushroom fruiting body and can eaten.

View Our Series Of Grow Guides

Who We Are

We’re a small scale producer of gourmet mushroom grain spawn and ready to grow kits located in South East Queensland. We’re passionate about fungi and we love sharing our obsession with the world.

Follow Us

Follow us on social media for updates on sales, new products and new tutorials.

Frequently Asked Questions

Do you have questions for us? We might have answered your question in our Frequently Asked Questions.