Troubleshooting guide

Something looks wrong with your grow? Answer a few questions about what you see and we will point you to the likely cause and what to do. The full list is below if you prefer to browse.

This guide covers cultivation problems only. It cannot identify wild mushrooms or tell you whether a mushroom is safe to eat.

Healthy signs

• Healthy growthEven, bright white mycelium fully claiming the substrate; firm pins or fruit with normal colour and shape; no …

Contaminants

• Green Mold (Trichoderma)Patches that start white then turn a distinct forest/lime green, usually spreading from a point; sharp musty s…
• Cobweb Mold (Dactylium)Wispy, grey, fast-spreading fuzz that grows OVER pins and substrate — looser and greyer than healthy mycelium,…
• Bacterial Blotch (Pseudomonas)Yellow-to-brown slimy or sunken patches on caps; a wet, off smell.
• Wet Spot / Sour Rot (Bacillus)Grey, greasy, translucent patches in grain or substrate that mycelium refuses to cross; a sour, rotten smell.
• Black Mold (Aspergillus / Rhizopus)Dark green-to-black powdery spots, often on a fuzzy base.
• Penicillium (Blue-Green Mold)Blue-green powdery mold, often with a white border, on grain or substrate.
• Orange/Pink Bread Mold (Neurospora)Bright orange or salmon-pink powdery growth, extremely fast and invasive.

Growing conditions

• Mycelial Overlay / StromaA thick, fuzzy, sometimes lumpy mat of mycelium that keeps growing but won't form pins.
• Long Stems, Small Caps (high CO2)Leggy, stretched stems with tiny or trumpet-shaped caps; oysters reaching upward.
• Dry / Blob Growth (low humidity)For Lion's Mane, a dense round blob with no spines; on other species, cracked or crusty cap surfaces.
• Aborted PinsSmall pins that form and then shrivel, yellow or blacken instead of maturing.
• Colonization StallMycelium that slows or stops partway across the substrate with no discoloration.

Last updated: 2026-10-19