King Oyster (Pleurotus eryngii) is grown for its thick, meaty stems. Their firm, scallop-like texture holds up to searing, roasting and grilling, and the mild umami flavor makes them a restaurant favorite.
- P. eryngiiSpecies
- ~5 lbColonized grain
- 60–70°FFruiting temp
- IntermediateSkill level
- 12–13Master's Mix bags
Why grow King Oyster from our spawn
Restaurant quality
Substantial fruits with a firm bite.
Sawdust grower
Best on Master's Mix or supplemented hardwood sawdust.
Worth the patience
Colonizes a little slower than other oysters, so give it time before fruiting.
From bag to block
1Break it up
Squeeze and massage the sealed bag until the grain separates into loose kernels.
2Set up clean
For a simple Master's Mix spawn, a clean room with still air works. For grain-to-grain or other open work, use a flow hood.
3Spawn about 1:3
Roughly one part spawn to three parts substrate, or about 2 cups per 5 lb bag of sterilized Master’s Mix. One bag covers 12–13.
4Seal and wait
Seal the bags, mix thoroughly and let them colonize at 65–75°F before moving to fruiting conditions.
King Oyster grain spawn specs
| Spec | Detail |
|---|
| Scientific name | Pleurotus eryngii |
| Mycelium | White and dense |
| Grain | Mostly white and red millet with a little milo |
| Bag | Unicorn 3T, 3-mil, 0.22-micron filter patch |
| Sterilization | 3-hour autoclave cycle |
| Weight | 5 lb net; bags usually fill to about 5.5 lb |
| Spawn rate | About 1:3; one bag spawns 12–13 bags of 5 lb Master's Mix |
| Best substrates | Master's Mix, supplemented hardwood sawdust |
| Fruiting temperature | 60–70°F |
| Skill level | Intermediate |
| Type | Gourmet |
| Shelf life | Best within about 90 days; up to 120 days refrigerated at 35–40°F |
| Ships | Same or next business day |
Where our genetics come from
Our master culture collection is the product of years of isolation work in our Illinois lab. We've added to it through a partnership with a leading commercial culture supplier in Canada and with select strains from the UK and Asia. Every culture is kept as first-generation commercial genetics and chosen for clean, vigorous colonization and fruit that's true to type.
Common questions
Is King Oyster harder than other oysters?
A little. It colonizes more slowly and is rated intermediate, but it's very manageable with clean technique.
What temperature does King Oyster fruit at?
How long will the spawn keep?
Use it within about 90 days for the best results. Refrigerated at 35–40°F, it can last around 120 days.
Do I need a flow hood?
Not for a basic Master's Mix spawn in a clean, still room. For grain-to-grain expansion or other open work, use a flow hood or clean room.
What if the bag arrives damaged or contaminated?
Every bag ships fully colonized and is inspected first. If something's wrong, contact us within 5 days of delivery with a photo and we'll send a free replacement.
Made fresh, shipped fast
Each bag is sterilized for 3 hours in an autoclave, inoculated under HEPA-filtered laminar flow and left to colonize completely in a dedicated clean room, then inspected before it ships. Millet's small kernels mean more inoculation points per pound, so the spawn spreads quickly and evenly through your substrate.
We produce on a rolling schedule instead of stockpiling, so your spawn is fresh. It usually ships the same or next business day in padded packaging, with a free cold pack from May through September or for hot destinations.
King Oyster spawn, fully colonized
Broken up and ready to spawn
When it arrives: Break up the grain and spawn it soon. If you can't use it right away, refrigerate it at 35–40°F.