Do Mushrooms need Light? | Improve Mushroom Cultivation (2024)

Some typesof mushrooms do need light, some don’t.

Back in1980, Eger-Hummel placed mushrooms into four different categories according totheir need for light (Fig. 1).

Group A:Light and darkness play no role at any stage of fruiting body development.

Group B:Light and darkness play no role in primordium formation, but the light isrequired at later stages of mushroom development.

Group C:Light is required except for a short period at an early stage of developmentwhen darkness is essential.

Group D:Light is required at all stages of fruiting body development.

Do Mushrooms need Light? | Improve Mushroom Cultivation (1)

Figure 1: Requirementsfor fruiting in mushrooms[1]

But a wordof caution. Not every mushroom can be placed precisely into one of these fourcategories. This is mainly due to the complex mechanisms which are still notall well understood. Therefore, it can happen that one mushroom, which is, forexample, in category D, actually belongs to category B[2].

Examplesfor each of these four categories are[3]:

Group A: Agaricusbisporus

Group B: Lentinustigrinus

Group C:Coprinus congregatus

Group D: Favolusarcularius

Why somemushrooms need light, and some don’t, we can only understand by looking at themushroom cycle itself.

What isthe Mushroom Cycle?

In general, the mushroom cycle (Fig. 2) can bedivided into two phases – vegetative phase and reproductive phase. “Thevegetative stage is referred to […] as the spawn running phase[4]” and “the reproductivestage as the fructification phase.[5]”

Do Mushrooms need Light? | Improve Mushroom Cultivation (2)

Figure 2: Mushroom life cycle[6]

Let’s divea little bit deeper into this fascinating world.

Let’s dive a little bit deeper into this fascinatingworld.

We start with the spore, which produces aprimary mycelium. “A mycelium is a vast network of interconnected cells thatpermeates the ground and lives perennially.[7]”

The growth of the mycelium “results in a fusionof the hyphae and a close association of the hyphae with the substrate.[8]”

This growth happens during the vegetativephase.

The part of a fungus that we usually call amushroom is the fruiting body of a fungus. The building of the fruiting bodiesonly occurs if there are triggers that signal the fungus to initiate theprocess and get ready to reproduce.

Such triggers can be a change in temperature, achange in the CO2/O2 ratio, and or light (Fig. 3).

Do Mushrooms need Light? | Improve Mushroom Cultivation (3)

Figure 3:The two major phases of mushroom growth and development[9]

Now to grow mushrooms ourselves, we have, therefore, emulate the nature of the fungus we want to grow.

How are mushrooms sensing light?

It was found that some fungi contain genes that are responsible for the circadian clock, which itself is linked to light. These genes are called white collar-1 (WC-1) and white collar-2 (WC-2) and are part of the LOV (light-oxygen-voltage) domain. These two genes respond to blue light and act like photoreceptors.

After finding these two genes, researchers starting to look into other mushrooms and found similar genes, for example, in Lentinula edodes (Shiitake) and Pleurotus ostreatus (Oyster mushroom).

The photoreceptors in Shiitake are called Le.phrA and Le.phrB and are primarily active during the fruiting body stage.

In a science paper from 2015, the author[10]mentioned that no WC-1 or similar gene was found in Pleurotus spp. which would mean that Oyster mushroom doesn’t respond to blue light. But in a recent article, two similar genes were announced[11]. They are called PoWC1 and PoWC2.

In addition to the blue light photoreceptors, it could be shown that there are red light and far-red light photoreceptors (phytochromes) within some mushrooms[12].

How to triggerpinhead formation?

If we, forexample, want to grow Oyster mushrooms (Pleurotus spp.), we need a phase ofdarkness and a phase at which we will introduce light.

Let’s startwith the inoculation of our spawn material. Here we transfer a piece ofmycelium from a petri dish and place it onto our spawn material. The myceliumthen starts to grow through it and, by doing so, expands. This happens totallyin darkness. There is no light needed. Quite the opposite.

The time tofully colonize our spawn material depends on the quantity of the substrateitself and the growing conditions – mainly temperature.

After thespawn material is fully colonized, we then transfer a part (around 5 %) ontoour primary substrate. And the process starts again. After the substrate isagain fully colonized, we want to “tell” the fungi to produce fruiting bodies.

How longdoes it take to fully colonize a substrate?

Dependingon the quantity of the substrate and the growing conditions (temperature,humidity, and CO2 level) it can take a while in order to colonize the substratefully.

Table 1gives you an overview of how long it can take to colonize your spawn and yoursubstrate fully. As shown in this table, it can take up to 70 days to fullycolonize the substrate. But only 14 days is possible as well.

That means besides the quantity of our substrate and the growing conditions, the mushroom species you want to grow influences the speed of colonization.

If you want to learn more about the impact of different parameters on the time to fully colonize your substrate you can find more information in my article How long does it take to colonize a bag fully?

Do Mushrooms need Light? | Improve Mushroom Cultivation (4)

Table 1: Overview of different growing conditions for various mushroom species[13]

As said,after the substrate is fully colonized, we want to trigger the fungi. In doingso, we move from the vegetative phase to the reproductive phase (Fig. 3). Thesetriggers are called environmental factors.

An exampleof this point can be seen in figure 4. Hereafter 14 days, the light level isincreased from 0 Lux to over 1,200 Lux. This level is kept for 4 more days andthen lowered to just below 800 Lux.

Thisprocess step triggers the formation of pinheads (Primordia), which then willgrow into the fruiting bodies, aka mushrooms we can harvest.

Do Mushrooms need Light? | Improve Mushroom Cultivation (5)

Figure 4: Example of light intensity during the cultivation[14]

An important side notes: The amount of light you expose your mushroom and the type of light has a high impact on the growth of your fungi[15].

But asshown in figure 1, not all mushrooms need light or to be more precise, thechange darkness/brightness to start pinning.

Summary

If the light is needed and how much depends on the type of mushroom and the phase, the fungus is in.

During thespawn run, they don’t need light at all.

To initiatethe pinhead formation (which means moving from the vegetating phase to the reproductivephase), light is for some mushroom types needed.

This is true as well during the growth phase of the fruiting bodies.

If you want to improve your yield than the right lighting can help you to do so. You will find more information in my article “How light will impact your mushroom yield.