King Blue Oyster Grain Spawn

Commercial-grade King Blue Oyster grain spawn — the Mossy Creek Mushrooms strain we grow at Cotaco Creek Mushroom Farm. Fast-growing, high-yielding, and known for dense, meaty clusters with usable stems. Suitable for prepared straw, hardwood sawdust, and Master’s Mix substrates.

What You’re Getting

King Blue is an oyster strain originally developed by Andrew Reed of Mossy Creek Mushrooms. It combines Blue Oyster and Elm Oyster genetics; despite the name, it is not a King Oyster mushroom. It’s substantial stems and caps make it a strong choice for growers selling to chefs, markets, and retail customers.

Your order contains fully colonized grain spawn, ready to mix into a properly prepared bulk substrate. We grow King Blue at Cotaco Creek Mushroom Farm in Somerville, Alabama, and offer it because it has earned a place in our own production lineup.

Why King Blue?

• Meaty, marketable clusters. King Blue produces dense mushrooms with firm stems and caps, so more of each harvest can be used or sold.

• Strong production potential. Mossy Creek describes it as a fast-growing, high-yield strain; its reported yields come from its own growing conditions and are not a guaranteed yield per bag of spawn.

• More temperature flexibility than a cold-weather Blue Oyster. King Blue can perform across a broad range, though protected, well-managed fruiting conditions give you more consistent results. Avoid excessive heat.

• Versatile substrates. Use it with pasteurized straw or properly sterilized hardwood-based substrates, including Master’s Mix.

Best Uses

• Sterilized hardwood sawdust or Master’s Mix fruiting blocks.

• Pasteurized straw bags, buckets, or columns.

• Grain-to-grain expansion in a clean workspace.

• Protected outdoor grows when weather and pest pressure are favorable.

Growing Parameters

These are starting targets, not a promise of identical results in every room. Adjust based on your substrate, block size, airflow, and what the mushrooms are showing you.

Parameter Range:

Incubation temperature: 68–75°F; leave space between blocks so they do not overheat.
Fruiting temperature: 55–75°F for dependable starting conditions; Mossy Creek reports that the strain performs across a wider range but thrives below 85°F.
Fruiting humidity: About 85–95% RH, with fresh air and no standing water on the mushrooms.
Light: Indirect ambient light or a regular daily light cycle.
Substrates: Pasteurized straw; sterilized hardwood sawdust or Master’s Mix.

The 55–75°F fruiting range and 85–95% RH range are published guidance from another King Blue spawn seller; Mossy Creek’s own guidance is broader and warns against excessive heat, flies, and bacterial blotch.

Storage & Handling

Use living spawn as soon as practical after delivery. If you cannot use it right away, keep the bag sealed and refrigerated, do not freeze it, and let it come toward room temperature before breaking it up and inoculating your substrate. Inspect the bag on arrival and contact us before using it if you see unusual colors, a damaged seal, or excess liquid.

About Cotaco Creek Mushroom Farm

We’re a small commercial mushroom farm in Somerville, Alabama. We grow the strains we offer and understand what matters when spawn is headed into a real production run: healthy colonization, careful handling, and practical guidance when you need it.

FAQ

Can I use this to make more grain spawn?
Yes. Grain-to-grain transfers are possible if you have sterile grain and a clean transfer setup, such as a flow hood or properly used still-air box. Each expansion adds contamination risk.

What inoculation rate should I use?
Start around 10–15% grain spawn by wet substrate weight for prepared straw or hardwood-based blocks, then adjust to your process. For example, a 10 lb prepared block at 10% receives about 1 lb of spawn.

Do I need a pressure cooker or autoclave?
For supplemented hardwood substrates such as Master’s Mix, use a validated sterilization process. Straw is commonly pasteurized instead. Let either substrate cool to inoculation temperature before adding spawn.

Is this a grow kit?
No. Grain spawn is the inoculant. You still need to prepare a bulk substrate, let it colonize, and provide fruiting conditions.

Will King Blue grow outdoors in Alabama?
It can work in a protected setup during suitable weather, but outdoor results depend heavily on temperature, moisture, insects, and contamination pressure. For more predictable production, start with blocks or straw bags in a controlled space; Mossy Creek specifically advises keeping flies off blocks and avoiding excessive heat.