How Much Light Do Mushrooms Need to Grow?

Some species of mushrooms do not need light at all to grow. Others, such as the Psilocybe cubensis, actually need a lot of light to produce healthy, mature fruiting bodies. However, opinions differ on how much light mushrooms really require. Read on to find out everything you need to know about lighting for your next mushroom grow!


When you start growing mushrooms at home, you roughly go through seven steps: preparation, inoculation, colonization, preparation of the growth chamber, fruiting, harvesting and drying. This cultivation method was developed in 1991 by Robert McPherson. We also know this method as the PF Tek method. To grow fruiting bodies, you need to start with the mycelium. To do this, you first fill a container with substrate mixture. After that, most growers choose to sanitize and steam the substrate. This is to protect against contaminants. Then you inject mushroom spores into the substrate. You put that in a place out of reach of direct sunlight for 7-14 days. After a few days, a fluffy white mycelium begins to grow. When the container is completely colonized with mycelium, it’s time for the “pinning” process. Pins are clumps of mycelium that eventually grow into fruiting bodies. The container should be at room temperature and you should expose it to a regular light cycle. This will ensure that the process runs smoothly. The pinning process takes between 5 and 30 days. After this, you can transfer the resulting mycelial cake into a transparent container that allows some light to reach it (such as a terrarium). Make a layer of 1.5cm perlite or clay pellets on the bottom and place the cake on top. The fruiting bodies should start growing within the next 7-14 days. Alternatively, you can simplify this whole process by purchasing a mushroom growing kit from Zamnesia. This contains a fully colonized substrate, perlite, vermiculite and a grow bag. You won’t have to perform as many operations.


Opinions differ on what type of lighting works best for mushrooms. For example, some growers prefer specific LED lights. Others swear by natural daylight. The mycelium may not need light to grow, but you can’t assume the fruiting bodies can do without it. Whether you choose natural or artificial lighting, at least some light is needed to complete fruiting. It also ensures that the fruiting bodies will grow in the right direction. Some growers prefer fluorescent (CFL) lighting. By using artificial light, you can be sure that the mycelium is getting what it requires, even in the absence of natural sunlight. When looking for a grow light for your mushrooms, you should pay particular attention to intensity and heat production. Especially hotter lamps that approach the blue end of the light spectrum are ideal. For example, consider “daylight” fluorescent tubes with a brightness of 6000-7000 Kelvin. In addition, as a general recommendation, you should not use energy-hungry incandescent bulbs for mushrooms. This is because these emit ‘red’ light with a low intensity of 3000-3500 Kelvin. However, many growers also report that they can grow healthy, mature mushrooms using only natural or ambient light. It turns out that mycelium requires only a small amount of light to grow and bear fruit. So putting your terrarium or grow kit in a location with a healthy amount of indirect sunlight or room lighting should be sufficient. Many growers believe that indirect sunlight at a window shade is the best light source. All in all, your fruiting bodies need at least some light. Don’t assume your mushrooms will grow in the dark!


Opinions differ on this topic as well. While some growers rely on a set schedule of 12/12 lighting, others choose to give their mushrooms less light. With a 12/12 schedule, you can be sure that the mushrooms will get enough lighting to grow. However, that much light is probably not necessary. You can often complete fruiting with less. Depending on the light intensity, it may even be harmful to give your mushrooms 12 hours or more of artificial light. Lamps that give off less than 7000 Kelvin are often fine and can be left on longer. However, are you afraid that the light is too intense or will burn your substrate? Then feel free to limit the amount to 3-4 hours per day.


You should always avoid excessive heat. If you place the lamps too close to the terrarium or mycelium, it can lead to overheating or burning. This will damage your mushrooms or cause the fruiting bodies to not appear at all. So never forget to keep some distance and keep an eye on your mushrooms. This will prevent damage from burning, especially if you use intense lights.