Candidates For Cultivation: The King Oyster Mushroom

Oyster Mushrooms come in a dizzying variety of colors, shapes and sizes. One true standout is the king oyster mushrooms. Unique in many of its characteristics, the King Oyster has a stately appearance and culinary flexibility making it well deserved of its name.

Scientific Name: Pleurotus Eryngii

General Description

Unlike other oyster varieties, the King Oyster doesn’t usually produce a shelf like formation, but instead produces a mushroom with a round cap and a defined stem.

The cap usually unrolls with age, becoming flat and eventually uncurled. If grown indoors with minimal fresh air and low light levels, the mushroom will grow a fat tall stem and a tiny cap, while lots of fresh air and light will produce a mushroom with a small stem and large dark cap.

King Oysters can be quite large, sometimes producing single fruits weighing well over one pound.

King oysters growing indoors.

Genetically identical, growing outdoors.

Natural Habitat: Found growing from the roots of hardwood trees, emerging from underneath the soil. Can be found in Southern Europe, North Africa, Central Asia and Russia.

Difficulty: Medium.

Agar: King Oyster mycelium grows vigorously on Malt Yeast Agar. Growth is somewhat slower than other Oyster species. Mycelium appears thick and fluffy. Sometimes rhizomorphic.

Spawn Types: Grains, especially Rye. Can also use millet, or wild bird seed. Hardwood sawdust is also an effective spawn medium.

King Oyster growing out on Agar.

A liquid Culture of King Oyster growing through sawdust.

Substrate Types: King oyster grows best on supplemented hardwood sawdust in autoclavable grow bags. Supplement with wheat bran at 10-15%. King Oysters will also grow well on straw, however, unlike other Oyster species, the yield will be reduced.

Cultivators also report that the King Oyster will have a longer shelf life and a better texture if grown on hardwood sawdust rather than straw.

Fruiting Containers: Large gusseted autoclavable grow bags with a filter patch will produce the best results. For straw logs use poly tubing. Can also be grown with success outdoors in garden beds.

Casing Layer: Unlike other Oyster mushrooms, the King Oyster will benefit from a casing layer. Use 50/50 peat moss and vermiculite with 1% hydrated lime to prevent casing contamination.

Yield: Typically, 1 lb can be grown from a 5 lb supplemented sawdust block on the first flush. Multiple flushes can be achieved. Some cultivators get 2 lbs from a block on a single flush.

Baby King Oyster Emerging from a casing layer.

Indoor grown King Oysters at different stages of development

Harvest: When to harvest the King Oyster depends on cultivators preference. Smaller younger mushrooms will generally have a better texture and flavor, but less yield will be achieved. King Oysters are unique among oysters in that the stem is highly desired for culinary uses, so allowing the stem to grow large may be desired. Harvest by removing the mushrooms at the base of the stem, being careful not to damage the top of the block if subsequent flushes are desired.

Freshly harvested King Oyster Mushrooms. Grown indoors. Yum.

Weakness: King Oysters are generally resilient against contamination but can be susceptible to blotch. Blotch is a bacterial infection generally caused by excessive humidity. It is shown by dark spots on the mushroom fruitbody. Remedy by reducing the humidity and ensuring water droplets do not remain on fruitbody for too long. Increase air exchanges.

Cooking: King Oyster mushrooms have a thick meaty texture and a bold unique taste. They are quite versatile and highly desired as a culinary treat. The thick texture will even stand up to grilling on a BBQ!

Spawn Run:
Incubate the grain spawn at room temperature (20-22 deg C) until full colonization. Should take 10-14 days for full colonization.

Initiate Pinning:
Expose fruiting container to lower temperatures (15 deg) and high humidity (95-100% RH). Increase fresh air.

Fruit Development:
Temperatures between 15-18 deg C. Lower humidity slightly but maintain above 80%. Fruits develop in 4-8 days.

You will not be disappointed choosing to grow King Oyster! The ones you grow at home will generally be much more delicious than the imported ones you can buy from the grocery store.

They are fun to watch grow, as they grow large and relatively fast. They store for much longer in the fridge than typical oyster mushrooms, sometimes lasting for longer than 2 weeks. You can have fun altering the growing conditions to produce vastly different looking mushrooms.

Overall, the King Oyster mushroom is a perfect candidate for cultivation.