The Most Common Mushroom Growing Problems and How to Solve Them

Whether you are new to cultivating mushrooms or an experienced grower, there is always a chance you could run into problems.

While growing gourmet or medicinal mushrooms can be straightforward, numerous things can go wrong. Many factors can negatively impact your project, from contamination to inappropriate growing conditions.

Knowing the typical reasons why mushroom cultivation fails will allow you to avoid these potential pitfalls. And in the worst-case scenario, you will know how to troubleshoot and hopefully prevent your hard work from going to waste.

This informative guide discusses some of the most common mushroom growing problems you might encounter. We will also explain some of the biggest challenges associated with each stage of the process and how to solve them.

Common Mushroom Growing Problems

The process of growing mushrooms varies significantly depending on the species, method, and whether you are growing indoors or outdoors. However, all grows have a few basic requirements, particularly:

  • Moisture
  • Fresh air
  • Light

Failure to provide enough moisture, air, or light will impair the mushrooms’ growth. However, there are numerous other factors to consider.


This article will focus on what can go wrong when growing mushrooms. For a general overview of the process, check out our beginner’s guide to growing mushrooms. Otherwise, read on to learn about the most common mushroom growing problems and how to solve them.

1. Contamination

Fungi thrive in warm and moist environments. Unfortunately, these conditions are also ideal for contaminants like bacteria and mold. These unwanted microorganisms compete with the fungus for nutrients and inhibit its growth. They also make any mushrooms that do manage to form unusable.


Contamination is a significant threat, especially in the early stages of mycelium growth before the fungus has developed an immune system. However, it is essential to be vigilant at all stages of growth and immediately deal with any contaminants.


It is essential to have a clean workspace and good personal hygiene. Sterilize all equipment with 70% isopropyl alcohol, wash your hands, and wear gloves and a face mask where possible. Grains should also be sterilized and substrates pasteurized before use.

Serious mycologists should consider investing in specialist equipment, such as a laminar flow hood and pressure cooker. The former acts as an effective air filter, while the latter is necessary for sterilizing grains.

Serious mycologists should consider investing in specialist equipment, such as a laminar flow hood and pressure cooker.

At a bare minimum, work should be carried out inside a still air box to minimize the risk of contamination. Moreover, your mushroom project should be kept away from pets and disturbed as little as possible.

You should also familiarize yourself with the appearance of different contaminants that could affect your grow. Healthy mycelium is white. Any brown, black, green, orange, or pink patches could be a sign of contamination. Remove affected bags or jars from the grow space immediately and dispose of them safely.

2. Not Enough Moisture

As we have mentioned, moisture is one of the most critical environmental considerations when growing mushrooms. Without enough humidity, the mycelium will dry out and die. Furthermore, mushrooms have a high water content. If they do not have enough moisture as they grow, they can become dry and brittle with cracked caps.


Give your substrate a good soaking and squeeze out the excess water before inoculating it with your spawn.

If you grow mushrooms in an enclosed environment such as a unicorn bag or monotub, the substrate should retain enough moisture until you initiate fruiting. Then, mist your container several times daily during the fruiting stage, or invest in a humidifier.

If you are growing mushrooms outdoors, you may need to provide additional water during dry weather. Choosing a naturally shady spot for your project or using shade netting can help to minimize water loss.

3. Too Much Moisture

Too much moisture can be as harmful to your mushrooms as too little. Puddles of standing water quickly become stagnant and encourage the growth of contaminants like mold.



Provide ample drainage and do not overwater your project. Little and often is better than drenching your substrate in more water than it can absorb.

4. Not Enough Fresh Air

Fresh air exchange is essential for healthy mushroom formation. If there is too much carbon dioxide and not enough oxygen, your mushrooms may be stunted with small or deformed caps.

Lack of fresh air can also cause “fuzzy feet,” whereby mushrooms develop additional mycelium at the base of their stems. While this is not necessarily harmful, it means the fungus is wasting energy that could be put into producing more mushrooms.


During the fruiting stage, open your containers for a few minutes once or twice daily to allow fresh air exchange. Some growers recommend investing in a fan, although you can also fan your containers manually.

5. Not Enough Light

Mushrooms do not require light to produce energy in the same way as plants do. However, they do need some ambient light to develop properly. Mushrooms grown in poorly lit areas tend to have long, spindly stems. They may also lean in one direction as they search for light.



If growing indoors, choose a room that receives enough natural daylight, or invest in a grow lamp. Outdoor growers usually needn’t worry too much but should avoid growing mushrooms in heavily shaded areas.

6. Wrong Climate

Different mushroom species naturally grow in different regions and, therefore, prefer different temperatures. This is a crucial consideration for outdoor growers. Trying to grow a tropical species in a cold climate will likely be unsuccessful and vice versa.


Outdoor growers should research which mushrooms will grow well in their region and opt for those.

Indoor growers have greater control over their environment. Therefore, they can grow a greater variety by using equipment such as a seedling heat mat to provide additional warmth if necessary.

7. Wrong Substrate

It is possible to grow mushrooms on various substrates, including wood, straw, coco coir, and compost. However, choosing a suitable substrate for your mushrooms is just as important as choosing the right climate. Some species are fussier than others and will not grow unless you provide the optimal medium. For example, wood-lovers like reishi and lion’s mane are unlikely to grow well on soil.



Research the variety you intend to grow and make sure you provide its preferred substrate. You could also consider supplementing with additional nutrients to maximize your yield.

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8. Faulty Spawn

Sometimes a grow can fail simply because of faulty spawn. Possible issues include spawn that is already contaminated or takes too long to arrive and dies.

Spawn can also go bad if you don’t use it quickly enough. Either way, faulty spawn means your project is doomed from the outset.


Only buy spawn from reputable suppliers that have a fast shipping time. Check your spawn over when it arrives and use it as soon as possible. You can store it in a refrigerator for a few days if necessary. However, in general, the longer you wait, the more chance there is for something to go wrong.

9. Too Much or Too Little Spawn

Using the right amount of spawn can be a delicate balancing act. Too little will leave your substrate vulnerable to contamination, and colonization will be slow. Meanwhile, too much could create excessive thermogenesis.


Thermogenesis means that as mycelium consumes nutrients from its substrate, it produces heat. Too much spawn means too much thermogenesis, resulting in overheating and mycelium death.


Do some research and use the appropriate amount of spawn for the volume of the substrate. Many growers recommend using around 20% spawn to 80% substrate. However, this can vary markedly depending on the species and substrate type.

10. Lack of Knowledge

You don’t need to be a professional mycologist to grow mushrooms. In fact, it is a wonderful way to learn about them. However, a complete lack of understanding could lead to errors and the failure of your crop.


Before even starting on your first grow, do some research. Learn the basics of the mushroom life cycle and what to expect. Find out which species are suitable for your climate, and decide whether you want to grow indoors or outdoors. There are countless resources available online, so take advantage of them to avoid silly mistakes.

11. Lack of Patience

Growing mushrooms takes time, and being impatient is potentially one of the biggest problems.

Mushroom farming can be labor-intensive, and some people may become overwhelmed, leading to problems.

For example, overenthusiasm could cause you to initiate fruiting before your substrate is fully colonized. This could result in low yields or, worse still, contamination. Another common mistake is not letting pasteurized substrate cool sufficiently before adding the spawn and killing it.

Trying to do too much at once is also the downfall of many new growers. Mushroom farming can be labor-intensive, and some people may become overwhelmed, leading to problems.


Go slow and steady. Take your time to research each step thoroughly and resist the temptation to rush.

If you are brand new to growing mushrooms, consider starting with a commercial mushroom grow kit. These are pre-colonized blocks of substrate that are ready to fruit. You just need to add water. Once you have completed your first grow successfully, you can move on to using pre-made grain spawn and, eventually, create your own.

Finally, don’t give up hope if nothing seems to be happening. Some mushrooms can take months to begin fruiting so wait a little longer, check the conditions are right, and hopefully, your patience will be rewarded.

12. Improper Harvesting

Even once you have successfully produced a flush of mushrooms, there are still things that can go wrong. For instance, harvesting too early can mean the mushrooms have not developed fully and will be small and light. Meanwhile, harvesting too late can cause the mushrooms to go bad, ruining all your hard work.


It is also essential to consider how you harvest the mushrooms to avoid damaging the mycelium. Keeping the mycelium intact is the best way to ensure you get further flushes of mushrooms and boost your yield.


Most mushrooms should be picked when the cap is just starting to open out but before the gills are fully exposed. For oyster mushrooms, wait until the caps open out and start to curl up at the edges.

Harvest your mushrooms gently by holding the base of the stem and twisting them away from the mycelium. You can also use clean scissors or a sharp knife.

Mushroom Growing Problems: Summary

Mushroom cultivation is a fun and rewarding hobby. You get to learn about the fungal life cycle and have the satisfaction of watching your own delicious or medicinal mushrooms developing.

Although there are some potential pitfalls, most of them are easily avoidable. Do your research and watch out for the most common mushroom growing mistakes listed above.

One final tip is to label everything and carefully log every stage of your project. That way, if something does go wrong, you should be able to pinpoint your mistake and avoid making it again in the future.

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