Common mistakes with mushroom grow kits (and how to avoid them)

A mushroom grow kit It's simple and reliable to use, but many beginners still experience some mishaps. Often, these are small mistakes that lead to mold, lower yields, or even a failed crop. Fortunately, you can recognize and prevent most problems.

In this article we discuss the most common problems with mushroom grow kits, including tips and a handy colour chart to see if your grow kit is still healthy.

1. Mold and contamination (green, gray, or black)

Wrong: Not working cleanly enough. If green, gray, or black spots appear on the grow kit, this is usually a fungus that is stronger than the mycelium.

Solution:

• If the spot only appears after two weeks, you can often just keep growing.

• If it happens sooner, there's a good chance the mushrooms are no longer growing healthily, and it's best to throw the kit away.

👉 Hygiene is crucial: always wash your hands and work cleanly.

2. Traces on the cake (dark brown, purple or black powder)

Wrong: Harvesting too late. As soon as mushrooms are ripe, they release spores. These fall over the cake and other mushrooms.

Solution: Harvest mushrooms in time, just before the membrane beneath the cap detaches. Spores aren't harmful, but they do reduce quality and yield in the next flush.

3. Bacterial infection (reddish-brown spots or mucus)

Wrong: Too warm conditions or inadequate hygiene. Round brown spots or slime in the cake often indicate bacteria.

Solution:

• If only a part is infected, you can sometimes still complete the culture.

• If the entire set looks slimy or dirty: throw it away and do not use it again.

4. White fluff on the cake or stem

Good sign! White fluff is usually just mycelium growing extra.

Solution: As long as it stays truly white, there's nothing to worry about. If the lint gets too thick, moisture evaporates less effectively, so open the bag more often for fresh air.

5. Bruises on mushrooms

No problem: Blue streaks or spots are a sign of psilocybin (the active ingredient). This is often caused by bruising or old age.

Solution: Simply harvest. The bluer the mushrooms, the older they are → mushrooms gradually lose their potency.

6. Low yield or no growth

Wrong: Sometimes a grow kit doesn't get started properly. After 4 weeks, no pins or only a few mushrooms?

Solution:

1. Harvest everything that is there, even the small ones.
2. Fill the container with cold water and let it soak for 12 hours (cold shock).
3. Drain and start again.
   
   You can repeat this several times as long as you work cleanly.

7. Too much or too little air and moisture

• No condensation in the bag? → Spray the inside of the bag lightly with a damp cloth (never directly on the cake).

• Too much condensation? → Air the bag more often, otherwise growth will slow down or mold will develop.

• Insufficient air exchange? → Open the bag briefly 1–2 times a day to let in fresh air.

👉 Use this as a quick check while growing. Unsure? It's better to stop in time and start again, rather than risk an unsafe harvest.

Conclusion

A mushroom grow kit failed Usually due to minor errors in hygiene, temperature, or timing. Thanks to the tips above and the color chart, you can quickly see whether your crop is healthy or if there's a problem. This way, you'll get the most out of your grow kit and avoid disappointment.