Does Mycelium Need Light? (No, It Doesn’t)

Mycelium is referred to as a fungus with a root-like structure consisting of a network of fungal threads known as hyphae. It usually grows underground and thrives on the trunks of trees that have started rotting.

Mushrooms generally sprout from mycelium, which are the fruiting bodies of fungi. Even the single spores of the fungi grow into a mycelium.

But, does mycelium need light to grow?

Honestly speaking light is not mandatory for the growth of mycelium; however, during the initial stages and the growth of fruiting bodies, light is a very important aspect that produces good quality mycelium.

The growth of the mycelium is not solely dependent on the light intensity but also on the length of the lighting period during its diurnal rhythm. 

Does mycelium need light
Does mycelium need light?

Does mycelium need light?

In its mature state, the mycelium does not need light to grow. Since mushrooms are not plants, they do not use photosynthesis to prepare their food. Hence light is not important for their growth.

However, light is highly required during the initial stages, and at the phase of growth of the fruiting bodies, light is required. This yields a good-quality mushroom. 

Does mycelium need light (detail guide)
Does mycelium need light?

Role of Light in Mycelium Growth

Light plays an important role during the initial and fruiting stages of the mycelium. However, during its mature stage, it is not required. Apart from the intensity of the light, the length of the lighting period is also essential in the diurnal rhythm.

Certain mushrooms like psychedelic cubensis need ample light to turn into a proper healthy edible mushroom. Since the mycelium roots are located underground, light is required to maintain humidity which helps in the thriving of mycelium. 

Optimal Light Conditions for Mycelium

We learned that to develop mature fruiting bodies, the mycelium requires some light. Many people prefer to use LED or CFL lights on a specific schedule of 12 hours.

On the other hand, many people rely entirely on indirect sunlight for their growth. The optimum temperature for mycelium is 75F, and the pH balance should be 6-8.

To maintain this moderate temperature, some light is required to maintain heat. Fungi prefer shade to grow into mature edible mushrooms and support and reproduce the mycelium network.

Understanding Phototropism in Mycelium

Phototropism is known to be the process of growing an organism in response to light stimulus. It occurs in both plants as well as fungi. In mycelium, phototropism occurs either towards or away from the light.

Mycelium Growth without Light


Mycelium can always grow in the dark, and light is not necessary for its mature stage. However, with research, it has been observed that the radial growth of the mycelium is much faster when kept in the dark incubation rather than growing under light incubation.

The environmental conditions at night time are always well suited for their growth because the presence of humidity is much more. Whereas at daytime, because of the sun’s UV radiation, there is less humidity in the air which slows down the growth of mycelium.

Mycelium Growth without Light
Mycelium Growth without Light

Advantages and Disadvantages

Mycelium grows better in dark conditions with warm and humid temperatures. If they are grown in a cold and dry area, you must mist the mycelium and use a heater to keep up the temperature. However, too much heat and light would kill them, so growing the mycelium in the dark is better. 

However, certain species of mushrooms, such as Shiitake and Oyster, need light during their fruiting stage. Hence if you grow them in the dark, they might not grow properly. 

Techniques for Dark Mycelium Growth

Colonization is important to grow mycelium in the dark. It takes roughly 15-20 days. Initially, the growth would be slow, and the growth would gradually increase. Make the liquid culture of the particular mycelium you would grow and colonize the substrate with that. Colonization of the substrate should be done in layers.

First, place the colonization culture on the substrate and add more substrate. The growth of the mycelium would accelerate separately and mix into each other, thereby accelerating the colonization process.

Along with this use, a less nutrient-dense substrate such as straw as this would enhance the mycelium to convert more rhizomorphic. This would make them grow faster as they need to look for food.

Mycelium Growth with Light


Light is not mandatory for the growth of mycelium in its mature stage; however, in its initial stage and during the growth of the fruiting bodies, it is required. Light is required to maintain temperature.

Mycelium does not get any direct benefit from sunlight as its roots are always underground. But if you expose the mycelium to partial light, it helps maintain the humidity level, which helps the mycelium to thrive better.

Mycelium Growth with Light
Mycelium Growth with Light

Advantages and Disadvantages

Mushrooms and their mycelium need approximately 2 hours of light if you grow them indoors. This light can be either artificial light or partial sunlight, and it should not be very strong. However, please ensure that when you expose the mycelium to natural sunlight, the location should also have ample shade.

The quality of mushrooms always thrives better if they are exposed to light during their initial stage and their fruiting bodies. But if you expose them to too much light, they won’t grow properly, and they would even die. 

Techniques for Light-assisted Mycelium Growth

Fungi do not have chlorophyll in them. Hence they do not undergo photosynthesis. But light is essential for the fruit mushrooms to emerge and thereby support the network of mycelium that occurs underground. So if you are growing them indoors or in a closed greenhouse, then artificial light is required.

When you are growing the mycelium in light, you can grow them with the help of a mixture of manure and straw. Mycelium and its mushroom do not thrive at all at hot or cold temperatures. Hence partial light is required to maintain the temperature. Carbon dioxide plays a pivotal role in sprouting mycelium in mushrooms.

When the CO2 level decreases, the mycelium rises to the surface of the soil, forming the mushroom body.

How can I make mycelium grow faster?

If you have favorable weather conditions, the mycelium will grow faster. 

  • Substrate: To grow the mycelium, the preparation of the substrate is very important. The substrate is the main source of food for mycelium. So the way it is prepared depends a lot on the pace of growth of the mycelium. If you add a huge spawn to the substrate or the inoculation rate is high, then the mycelium would grow faster in the substrate. 
  • Humidity: Mycelium thrives best and faster in a humid environment. They would grow faster in moist areas rather than in scorching sunlight. You can use a portable humidifier if you grow them inside or in a greenhouse. 
  • Temperature: Temperature plays a pivotal role in the speed of growth of the mycelium. The ideal temperature range should be 65-75 degrees Fahrenheit. If the temperature exceeds this, the mycelium will dry up and eventually die. 
  • Light is not required in the mature stage of the mycelium; however, during its initial stage and fruiting bodies, some amount of light helps them grow faster and develop into good quality mushrooms. 
  • Nutrients: Nutrients are another crucial factor for mycelium’s quality and faster growth. If you want an adequate amount of mushrooms, you must add necessary nutrients like fats, protein, sugar, starch, nitrogen, and lignin during the mycelium stage itself. 

How can I tell if mycelium is healthy?

If you are interested in growing mushrooms on your own, then it is very important to identify the symptoms of a healthy or contaminated mycelium. Because depending on this, the quality of mushrooms would depend. Mycelium is mainly the vegetative part of the fungus, which is responsible for developing into fruiting bodies (mushrooms).

How can I tell if mycelium is healthy
How can I tell if mycelium is healthy?

A healthy mycelium would look white, fluffy, and dense without any other color or spots. The smell from the mycelium would be strong and earthy. If they have a yellowish tinge or look sickly, you should know they are contaminated. You can also test by cutting a minor piece of mycelium on a petri dish and providing food.

If it grows and eventually produces fruit bodies within a short period, then you should know that the mycelium is healthy. If it doesn’t grow, you need to start with the cultural material again. 

Frequently Asked Questions (FAQs)

Does mycelium need air?

For the growth of mycelium, fresh exchange of air is very important. Mycelium does breathe; similar to humans, they inhale oxygen and exhale carbon dioxide. During the colonization phase, as the mycelium remains underground, it can endure a high amount of CO2, but it would need ample fresh air exchange to breathe properly.

Does mycelium need sunlight?

Mycelium doesn’t need sunlight or any other light source during its mature phase. However, during the initial stage and the fruiting stage, it would need partial sunlight. You can place them near the window to absorb natural light, but be sure that the location has proper shade. You should not place them in scorching sunlight.

Does music help mycelium grow?

Mycelium responds very well to music, and studies have revealed that the influence of sound waves has accelerated the growth of the mycelium to 15%. Even the fruiting stage from the mycelium has increased its pace to 21%, advancing the harvest time by 1-5 days and accelerating the mushroom growth by 3-8 days.

What triggers mycelium growth?

Nutrients play a pivotal role in triggering the growth of mycelium. The mycelium usually releases enzymes from its hyphal tips, which help to digest the surroundings and absorb nutrients easily. So if you add the necessary nutrients during the initial stage of the mycelium along with ample humidity and proper temperature, it will surely trigger its growth.


The growth of the fungi to mycelium and eventually into healthy mushrooms depends completely on the right environment.

When the mycelium is at its initial stage, they need light to grow properly; however, when it reaches its mature stage, it doesn’t need artificial light or natural sunlight. When the mycelium converts to fruiting bodies (mushrooms), they need proper light.

But you need to be very sure that the light should not be very strong and that the temperature maintained is 75F with ample shade and enough humidity for mycelium growth. To provide the proper environment for the mycelium to culture healthy and adequate mushrooms. 

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