Why Your Magic Mushroom Grow Kit Is Not Growing (Causes & Solutions)

A mushroom grow kit is an accessible way to grow your own mushrooms^.1. However, not every grow is successful. Sometimes nothing happens at all. You may not see pins or mushrooms forming, only a white block that seems inactive. In other cases, discoloration or mould appears. This can be frustrating, especially if you carefully followed the instructions. The good news is that when a mushroom grow kit does not grow, there is usually a clear explanation.

If a mushroom grow kit does not grow, the cause is usually related to temperature, humidity, hygiene or fresh air. By adjusting these conditions, you greatly increase the chance of healthy pins and a successful harvest.

In this article, we explain what can go wrong, why these problems occur and how you can solve or prevent them.

What are the most common reasons a mushroom grow kit does not grow?

If a mushroom grow kit does not grow, you will usually notice one of the following problems:

1. No pin formation: small buds (pins) do not appear on the surface of the mycelium.
2. Pins stop growing: pins appear but stop developing and dry out.
3. Discoloration or mould: green, black or slimy spots can indicate contamination.
4. Dried substrate: the block becomes hard on top or starts to shrink.
5. Too much moisture: the surface becomes wet or soggy and may smell musty.

These are symptoms, not causes. The underlying causes are usually related to climate conditions, moisture balance, hygiene or timing.

Why can a mushroom grow kit fail to grow?

• Temperature problems
  Most grow kits perform best between 20 and 25°C^.1. Below 18°C, growth slows down significantly. Above 27°C, the mycelium becomes stressed and the risk of contamination increases.
• Incorrect humidity
  Mycelium needs high humidity to grow properly. Air that is too dry can cause pins to dry out before they develop. Too much moisture can lead to bacteria or mould.
• Lack of fresh air
  Keep the bag tightly closed until you see the first pins, then start airing your kit daily. Always read the manual carefully before you start growing. Some grow kits do not need to be aired.
• Insufficient light
  Grow kits do not need strong light, but indirect daylight helps stimulate growth. Complete darkness can slow down pin formation.
• Incorrect soaking
  Many grow kits need soaking before the first flush. Too little soaking can leave the substrate too dry, while soaking for too long can damage or suffocate it.
• Contamination
  Bacteria or mould compete with the mycelium. Even a small infection can stop growth completely.

Overview of common problems and causes

How to solve and prevent these problems

1. Check the temperature

Measure the room temperature with a thermometer. If it is below 20°C, move the grow kit to a warmer place. If the temperature is too high, place it in a cooler room away from direct sunlight.

2. Adjust humidity levels

If the substrate looks dry, keep the kit away from heaters and dry airflow. Lightly mist the inside of the grow bag and make sure the bag is closed properly. If the surface looks very wet, briefly ventilate the bag. Use less water and carefully remove excess moisture if needed.

3. Improve fresh air exchange

Open the grow bag briefly once or twice a day to refresh the air. This can help stimulate mushroom growth. Always check the instructions to confirm what is recommended for your specific grow kit.

4. Adjust lighting conditions

Place the grow kit in a spot with indirect daylight. Avoid both direct sunlight and complete darkness. Normal daylight in a room is usually ideal.

5. Check for contamination

If you see green powder, black spots or smell a sour odour, the grow kit may be contaminated^.2. In many cases, contaminated kits cannot recover. Remove them promptly to prevent contamination from spreading.

Frequently asked questions

Below you will find answers to common questions about mushroom grow kits that do not grow properly.

Read more about mushroom grow kits

Want to learn more about growing mushrooms and avoiding common problems? The articles below provide more information about techniques and mistakes to watch out for.

• Recognise, fix and prevent common grow kit mistakes – Learn which mistakes often occur and how to avoid problems related to temperature, humidity and hygiene.
• Cold shock method for grow kits – Discover when cold shock can help stimulate pin formation.
• What is a monotub growing method? – Learn how a monotub works and why some growers prefer this technique.

Sources

1. Paul Stamets – Growing Gourmet and Medicinal Mushrooms (2000)
2. Gastón Guzmán – Fungi from Different Environments (2009)

Disclaimer: This article is for educational and informational purposes only. Laws regarding psilocybin mushrooms differ from country to country. Always check your local regulations before using a grow kit. 24High does not provide advice about illegal activities. Always work carefully, hygienically and at your own responsibility.