King Blue Oyster Mushroom Spawn

King Blue Oyster Mushroom Spawn – 5 lb Bag

King Blue Oyster (Pleurotus ostreatus hybrid) is a robust strain selected for its large, heavy clusters and thick, substantial stems. This hybrid delivers the cold tolerance and vigour of Blue Oyster with meatier fruit bodies that appeal to chefs and consumers who want more substance in their mushrooms. It is an excellent choice for Canadian growers looking for a high-yielding, cool-weather strain that produces premium-quality mushrooms.

Why Growers Choose King Blue Oyster

• Large, heavy clusters – Produces bigger individual fruit bodies with thick stems, increasing the weight per harvest.
• Cold tolerance – Fruits well in cool conditions, extending your growing season through fall and winter in Canadian climates.
• Substantial texture – Thicker stems and meatier caps compared to standard Blue Oyster, appealing to buyers seeking a heartier mushroom.
• Strong colonization – Vigorous mycelial growth reduces contamination risk and keeps your production schedule on track.

What You Get

Each 5 lb bag contains fully colonized organic millet grain spawn from our CFIA-licensed production facility in Brantford, Ontario. Every batch is produced in-house from lab-tested genetics under strict sterile conditions. This ensures you receive consistent, contaminant-free spawn that performs reliably at scale.

How to Use

Mix grain spawn into pasteurized straw or supplemented hardwood sawdust at a 10–15% spawn rate. King Blue Oyster is versatile and does well on both substrates. Pack into XL grow bags or growing columns and colonize at 20–24°C. Once colonized, drop temperatures to the fruiting range and provide high humidity and fresh air. Expect dense, blue-grey clusters that mature over 5–7 days.

Growing Conditions

• Fruiting temperature: 12–18°C (54–64°F)
• Humidity: 85–95% RH during fruiting
• Light: Indirect ambient or 12-hour cycle
• Fresh air: High air exchange for compact, well-formed clusters
• Substrates: Pasteurized straw, hardwood sawdust, masters mix

For a warmer-season counterpart, try our Black Pearl King Oyster Mushroom Spawn. Need growing supplies? Browse our grow bags and substrate options.