What Are The Tiny Mushrooms Growing In My Greenhouse

Have you ever panicked and uttered, “what are the tiny mushrooms growing in my greenhouse?” With the extensive list of mushroom varieties, it’s almost impossible to tell the small mushrooms in your greenhouse immediately. At the same time, correct identification is unnecessary because they won’t harm your plants.

However, it’s best not to consume any mushroom you see as they could be poisonous. It’s typical for a gardener to feel disturbed seeing mushrooms in the ground, mulch, or pots of the greenhouse. But since mushroom cultivation as a food source is possible, there shouldn’t be any surprise to see these fungi growing in your greenhouse amongst the crops. 

What Are The Tiny Mushrooms Growing In My Greenhouse


Identifying What Are The Tiny Mushrooms Growing In My Greenhouse

According to David Fischer, author of Edible Wild Mushrooms of North America: A Field-to-kitchen Guide, many mushrooms can grow indoors, mulch beds, or lawns. Correctly identifying the tiny or small ones growing in your greenhouse would be impossible, so below are the types of mushrooms that you can expect in the greenhouse conditions. 


Common mushrooms that grow indoors

A typical small mushroom that grows indoors is Leucocoprinus birnbaumii. You might also see it in your pots in the greenhouse, thus, giving it the name flowerpot parasol and plant pot dapperling. If you live in a temperate region, you have a higher chance of seeing this mushroom. 


Common mushrooms that grow in mulch beds

The mulch beds are also prone to having Clitocybe nuda, Coprinus atramentarius, Coprinus micaceus, and Lepiota cepaestipes. The smallest ones are the last two, and only the last one can cause short-term gastrointestinal symptoms. You can spot them in the greenhouse when the climate is warm. 


Common mushrooms that grow on lawns

Agaricus campestris and Agaricus placomyces are common mushrooms that grow on lawns or the ground of the greenhouse. While these fungi aren’t tiny as their caps measure 4 to 7 inches wide, it’s not surprising to see them growing in ideal conditions like the previous examples. They are also common in the Rocky Mountains of western North America.


Why Do Mushrooms Grow In The Greenhouse?

There are many potential reasons why you see mushrooms growing in your greenhouse. For starters, you might use potting soil contaminated with fungus and the conditions in your greenhouse is ideal for its growth. This is the common reason you see mushrooms in your pots, especially when the environment is cold, humid, and moist. 

But what about the mushrooms that grow in your raised beds in the greenhouse? It might be because of the organic matter in the bed, contamination with potting soil, airborne movement, or from your clothing. Overwatering can also cause mushroom growth in raised beds because the area becomes moist and humid. 


Are Mushrooms Bad For The Greenhouse?

Mushrooms are fungi, and seeing them in the greenhouse will naturally make anyone worried. However, the good news is that mushrooms are not bad for the greenhouse. They are harmless to your plants and even offer benefits for them. 

For example, they improve the quality of the soil because they help with its nutrient content. Unlike weeds, mushrooms won’t compete for the nutrients in the ground. Instead, they add compost by decomposing the organic matter in the soil. 

You can think of the mushrooms and plants having a symbiotic relationship. They provide nutrients and increase the plant roots’ surface area, and the plants will produce sugars as fungi food. However, do note that there are still harmful fungi in the greenhouse.

Mushrooms are the good fungi, while the white powdery mold is an example of a harmful fungus that can be detrimental for your plants. Overall, mushrooms aren’t bad for your plants, but it’s better to get rid of them since they can make the greenhouse unsightly. Additionally, other human beings and pets may consume mushrooms, which can be harmful as some are very toxic. 


How To Control Mushrooms In The Greenhouse

As mentioned earlier, overwatering is a leading cause of mushroom growth in the greenhouse. Remember that water encourages mushrooms to grow because they thrive best in moist and humid environments. At the same time, be aware of contaminating your potting soil or mulch beds since mushrooms can also be airborne or transferred via clothing.

It can be hard to remove mature mushrooms because they can release more spores. Therefore, you can only remove small mushroom caps or use fungicide in the greenhouse. Lastly, ensure proper ventilation and air circulation in the greenhouse to prevent fungal growth. 



The thought of fungi growing in your greenhouse is unappealing. You might end up contemplating what are the tiny mushrooms growing in my greenhouse and immediately search for its species. However, there are so many mushrooms, so identifying what you see correctly is tricky. 

A typical small mushroom that grows indoors is the Leucocoprinus birnbaumii. Other species may also thrive in the greenhouse, given that the optimal growing conditions are available. The good news is other than being unsightly, mushrooms aren’t bad for your plants. 

Be aware of the potting soil you’ll use as this can cause contamination in the greenhouse. Overwatering and poor air circulation are two factors that can also support mushroom growth.

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