How do I know if my mushroom grow has a problem?

Warning signs include: unusual colours (green, black, pink, yellow) on substrate or jars, foul or sour smell, no mycelium growth after 2 weeks, wet slimy patches, mushrooms aborting before harvest, or excessive cobweb mold. Healthy grows show steady white mycelium, clean smell, and consistent pin development.

What does healthy grain spawn look like versus contaminated spawn?

Healthy grain spawn is bright white, rope-like or fluffy throughout, with an even coverage from the inoculation points outward. Contaminated spawn shows patches of green, black, pink, or yellow; may smell sour, sweet, or foul; and often has wet or slimy areas around the problem.

Can I save a partially contaminated grow?

It depends. Minor surface cobweb mold can sometimes be controlled with fresh air. However, any visible green (Trichoderma), black, pink, or yellow contamination means the jar or tub is unrecoverable. Attempting to fruit contaminated substrate risks spreading contaminant spores throughout your grow area.

Visual Problem Identification

[Image: White fuzz growing up the stem]

Fuzzy Feet

White, cotton-like mycelium growing up the base of the stem. It is perfectly edible.

Cause: Lack of Fresh Air (FAE). High CO2 levels.
Fix: Fan more often or increase air gaps.

[Image: Tiny mushrooms with black caps]

Aborts

Pins that stop growing and turn black/dark blue. They are actually VERY potent.

Cause: Substrate too dry, or the cake decided to focus energy on larger fruits.
Fix: Harvest them when you pick the big ones. Don't leave them to rot.

[Image: Thick, rubbery white mat on surface]

Overlay / Stroma

Mycelium becomes thick, rubbery, and impenetrable. Water rolls right off it. Pins cannot push through.

Cause: Low FAE, high temps, or genetics.
Fix: "Fork Tek" - Sterilize a fork and gently scrape lines across the surface to break it up.

[Image: Cap looks mutated, gills growing on top]

Rosecomb Mutation

Gills growing on the outside of the cap, or weird warped shapes. Edible and safe.

Cause: Contact with petroleum products (Lysol, cleaning fumes).
Fix: Stop spraying Lysol near your open tubs.

[Image: Pins growing sideways from tub walls]

Side / Wall Pinning

Pins appear on the sides or bottom of a transparent container rather than the surface. They are fully viable and can be harvested by removing the tub wall — though this is impractical in most setups.

Cause: Light penetration through transparent walls creating a surface signal for pins.
Fix: Wrap the outside of transparent tubs in black tape or cardboard from spawn run onward. Leave only the lid area clear.

[Image: Blue bruising on mushroom stem]

Blue Bruising

Mushrooms turn vivid blue or greenish-blue when pinched, dropped, or cut. This is a well-documented chemical reaction involving psilocybin oxidation and is a positive indicator of alkaloid presence. It does not indicate contamination or spoilage.

Cause: Oxidation of psilocybin to psilocin-quinone when mushroom tissue is damaged.
Fix: No fix needed — handle gently to avoid excessive bruising, which can affect aesthetics but not potency significantly.

[Image: Fully colonised block with no pins]

Fully Colonised — No Pins

The substrate is 100% white with mycelium but no pins appear after 2+ weeks of fruiting conditions. This is one of the most frustrating problems for new growers.

Common Causes:

CO2 too high — increase FAE duration or frequency
Humidity too low — should be 90-95% RH, not 80%
Temperature too high (above 27°C) — cool the space
No temperature drop cue — try a 24-hour cold shock at 15-18°C
Overlay/stroma — break surface with sterile fork (Fork Tek)
Strain-specific — some strains (PE) simply take 3-4 weeks

Quick Diagnosis Table

What You See	Likely Cause	Action
White fuzz on stems	High CO2 (Fuzzy Feet)	Increase FAE
Tiny dark aborted pins	Low substrate moisture or energy allocation	Harvest with main flush
Thick rubbery surface	Stroma / Overlay	Fork Tek surface break
Warped/gill-on-top caps	Rosecomb (VOC exposure)	Remove chemical sprays from area
Pins on tub walls only	Light penetration through container	Blackout tub sides
Blue patches on substrate	Normal bruising from handling	No action needed
No pins after 14+ days fruiting	Multiple: CO2, RH, temp, overlay	Check all parameters systematically