Description

• HK-35 Oyster Mushroom (Pleurotus ostreatus) liquid culture in a 12cc syringe — the globally recognized commercial benchmark strain
• Developed by Sylvan Inc. and adopted worldwide as the standard reference strain in academic oyster mushroom research
• Selected for rapid colonization, consistent high yields, and a short, efficient 3-day fruiting flush
• Suitable for inoculating sterilized grain, agar petri dishes, straw, hardwood sawdust, and coffee grounds
• Performs reliably across a wide temperature range — a proven strain for both hobbyist and commercial production
• Store refrigerated between 35–45°F; avoid freezing; use within 4–6 months of receipt

HK-35 Oyster Mushroom (Pleurotus ostreatus) Liquid Culture

Strain Overview

The HK-35 Oyster Mushroom liquid culture syringe contains the Pleurotus ostreatus strain that became the global standard for commercial oyster mushroom production. Developed by Sylvan Inc. and distributed worldwide, HK-35 is the strain that researchers and mycologists have used as the control benchmark in peer-reviewed cultivation studies across Europe, Asia, and North America — chosen precisely because of its consistency, predictability, and well-documented performance characteristics. When scientists in Ukraine, Armenia, or the Netherlands want to evaluate a new oyster mushroom strain, they measure it against HK-35.

For cultivators, that track record means something practical: HK-35 is one of the most thoroughly tested and reliably documented oyster strains available. It colonizes aggressively, produces dense clusters of large-capped fruiting bodies, and completes its fruiting flush in as little as three days — a trait that makes harvest timing predictable and labor-efficient. Out-Grow has carried this strain continuously for over a decade and remains one of the primary sources for HK-35 liquid culture in the United States.

HK-35 Oyster Mushroom — Cultivation Parameters

Natural Habitat & Ecology

Pleurotus ostreatus is a saprophytic wood-decay fungus found in temperate and subtropical forests throughout North America, Europe, and Asia. In the wild it grows on dead and dying hardwood trees — particularly oak, beech, and elm — decomposing cellulose and lignin and returning nutrients to the forest ecosystem. The species is cold-tolerant and fruits naturally in autumn and early winter, which is reflected in HK-35's reliable performance across a broad fruiting temperature range. In cultivation it adapts readily to a wide variety of lignocellulosic substrates, making it one of the most substrate-flexible oyster strains available.

Physical Characteristics

HK-35 produces large, broadly fan-shaped caps with a smooth surface and gently inrolled margins at pinning. Cap coloration ranges from pale grey to warm tan depending on fruiting temperature — cooler conditions produce darker, blue-grey caps with longer shelf life, while warmer temperatures yield lighter, cream-colored fruiting bodies. Gills are white and decurrent, flesh is firm and white throughout. Clusters are dense and well-formed, with caps averaging 8–15 cm in diameter under good fruiting conditions. The strain is noted for producing particularly uniform clusters with consistent cap sizing — a commercially significant trait that simplifies grading and packaging.

Edibility & Culinary Use

HK-35 is an edible, choice culinary mushroom with the mild, savory flavor profile characteristic of Pleurotus ostreatus. Its large caps and firm flesh hold up well to sautéing, roasting, and stir-frying. The mushroom has a subtle anise-like aroma when fresh and a clean, mild flavor that complements a wide range of dishes. As with all oyster mushrooms, harvest just before or at full cap extension for best flavor and texture — caps that have begun releasing spores are past peak quality and shelf life drops rapidly after this point.

Liquid Culture — Usage Instructions

This syringe contains living Pleurotus ostreatus mycelium suspended in a sterile nutrient broth. Shake gently before use to distribute mycelium evenly throughout the solution. Inject directly into sterilized grain jars or bags through a self-healing injection port, or transfer to agar petri dishes for isolation and expansion. Liquid culture delivers established, actively growing mycelium directly to the substrate, accelerating colonization relative to spore-based inoculation methods. Use sterile technique throughout inoculation to prevent contamination.

Storage

Store refrigerated at 35–45°F in a dark location. Do not freeze. Use within 4–6 months of receipt for best viability. Bring the syringe to room temperature for 30 minutes before use.

Taxonomy — HK-35 Oyster Mushroom (Pleurotus ostreatus)

• Kingdom: Fungi
• Division: Basidiomycota
• Class: Agaricomycetes
• Order: Agaricales
• Family: Pleurotaceae
• Genus: Pleurotus
• Species: P. ostreatus
• Strain: HK-35 (Sylvan Inc., USA)

Disclaimer

This product is intended for cultivation and research purposes. Always properly identify any mushroom before consumption. Out-Grow is an independent supplier of this culture and is not affiliated with or endorsed by Sylvan Inc. This product is not intended to diagnose, treat, cure, or prevent any disease.