How to grow healthy Mycelium?

Mycelium is a crucial aspect of mushroom cultivation. This fact suggests that to ensure a profitable mushroom harvest, you should secure the health of your mycelium. Such a task could be overwhelming for new growers.

Well, worry no more because this post is dedicated to guiding you in producing healthy mycelium.

How to grow mycelium?

Mycelium is a network of threads, which are also called hyphae, where mushrooms are expected to grow. Though not all mycelium generates mushrooms, all mushrooms originate from mycelium. Here are some steps you can follow to promote mycelium growth:

Equipment needed:

  • Substrate - could be straw, wood, coffee grounds, grains, etc.
  • Mushroom spawn
  • Mushroom growing bags
  • Large pot for pasteurization
  • 70% alcohol

Step 1:

Purchase premium-quality mushroom spawn since low-quality ones could complicate the process.

Step 2:

Here your goal is to sterilize the equipment which you will be using. To do this successfully, you should clean the equipment using 70% alcohol. It's beneficial to work on a spotless surface, like a table. Some farmers favor donning gloves while working. Although it's preferable, your growing room should be in a completely enclosed room.

Step 3:

Your chosen substrate could contain antagonistic microorganisms that could harm your mushroom growth. Allowing your substrate to undergo pasteurization is an effective way to eliminate these unwanted microbes.

The simplest pasteurization method involves soaking your substrate for an hour at 160F in water. Alternately, submerge your substrate for 12 hours in water with 0.2% activated lime. Place your substrate to drain and cool after pasteurization.

Step 4:

The fourth step involves inoculating the mushroom spawn. Mushroom spawn must be in contact with the substrate during inoculation to begin growing and developing. Depending on the substrate, inoculation may require punching holes in a log, carving wedges into a stump, or combining spawn into separate bags.

Since we are not using logs in this procedure, you can mix the treated substrate and spawn together to achieve this. This is typically done in buckets or other containers, as well as in specialized grow bags. Ensure the air filter permits fresh air exchange (these are already present in grow bags). There should be no more than 4-8% spawn in the final blend.

Step 5:

The last step is about incubating your strain which means letting it grow.

A room with a temperature range from 65 to 75 degrees Fahrenheit is ideal, along with 80 percent humidity. Do not forget to provide fresh air. Within 3–4 weeks, your mycelium should have colonized the substrate, wherein it should appear almost entirely white.

It has undoubtedly concluded its growth stage if you observe the emergence of fruiting bodies.

What to look out for when growing mycelium?

At this point, we will discover the important factors that contribute significantly to mycelium growth. Since we are talking about mycelium, I will share with you the intrinsic factors affecting it.

Six Intrinsic Factors

Suitable Substrate

As you may already know, mushrooms may grow on various substrates, including straw, wood, and grass. An excellent substrate has lots of lignin, cellulose, and hemicellulose, which are woody, fibrous components. (These are rich in carbon, which is your mycelium's primary food supply.) The following considerations are crucial when selecting a substrate:

  • You need 1% to 2% nitrogen in your substrate. To reach this threshold, the majority of substrates (such as sawdust or straw) require the inclusion of additional components.
  • Magnesium, potassium, calcium, phosphorus, sulfur, and modest amounts of the other elements are required in your substrate. These minerals are already present in most natural substrates, albeit this varies depending on the source of the material. Here, experimentation will probably be required to determine whether you need to take a mineral supplement.
  • Your substrate should have a PH level of between 5 and 6.5, making it somewhat acidic. (Some mushrooms, such as oyster mushrooms, can withstand a PH of up to 8.)
  • For air exchange to be possible, your substrate must have a solid structure. This is required for the mycelium to colonize successfully.
  • The moisture content of 50–70% is required for your substrate.
  • Finally, there must be no organisms that can compete with your substrate. Your mushroom mycelium can grow freely on a surface like this.

Size of Particles

Your substrate's particle size affects how quickly your mushroom grows, and this is a subject that not many people are aware of or discussing.

Comparing the development and, in particular, the yield of shiitake (Lentinula edodes) cultivated on a log or sawdust is an excellent approach to demonstrate this claim.

If you grow shiitake on logs, the first growth, which produces an average yield of 0.23 lbs, appears in year two. Instead, if you utilized sawdust, it would take 80 days to produce the early growth with a yield of about 1 lb.

You may ask, "How is that possible?"

Utilize the concept of density. The mycelium must grow through a dense substance when a log is inoculated. Sawdust has a reasonably low density in contrast. Consequently, mycelium can develop more quickly.

Second, due to the mycelium's slow growth, most energy it generates will go toward digesting rather than developing fruiting bodies. The mycelium is starting to feel worn out.

Substrate Moisture

Too much moisture in the substrate makes it harder for the mycelium to breathe, which deters the development of fruiting bodies. The fruiting body will also die if the moisture level is too low because it cannot absorb the right amount of needed nutrients.

pH Value

Your substrate's pH level directly affects the growth rate, the quantity of fruiting bodies, and the yield of your mushrooms. This indicates a significant relationship between pH level and outcome for each of the three values.

To balance the pH level to about 7, all mushroom producers, for instance, apply lime on the substrate. This practice is proven to be effective.

When growing oyster mushrooms (Pleurotus spp.), if you apply too much of it and reach alkaline territory (pH 8), expect stunted growth, resulting in a lesser yield. On the other hand, a higher acidic level (pH 6) cannot significantly impact growth.


The substrate's oxygen content is crucial since mushrooms require it to develop.

The amount of oxygen is affected by at least two variables. The first is particle size, while the second is the substrate's moisture content.

The particle's size creates gaps that affect the aeration of the mycelium. If the aeration becomes restricted, mycelium growth slows down, and this will be the case if the particle size is too small.

If the substrate's moisture level is too high, the oxygen supply of the mycelium is negatively affected. Such a reason necessitates that you monitor the moisture of the substrate you bought.

Does mycelium grow best in the dark?

Another relevant question we should ask is, "Does mycelium need light to grow?" The gist of it is that mycelium does not necessarily require light to grow. In contrast to higher plants, a fungi's mycelium does not produce energy through photosynthesis. Instead, they consume the nutrients through their hyphae as they digest decaying plant debris.

On the other hand, nature does not always give a direct yes and no answer to our queries. While mycelium does not need light to grow, some fungi, including oysters and shiitake mushrooms, use light as a catalyst to begin generating fruiting bodies. Therefore, it's better not to maintain your mycelium in complete darkness if you wish to harvest fruiting bodies from it.

Light, or lack thereof, is one of the least crucial elements to control when cultivating fungi. Nothing specific about the darkness stimulates mycelium development. Instead, the lack of light promotes the moist conditions necessary for the mycelium to develop.

The best strategy to guarantee that your mycelium grows quickly and produces a large number of mushrooms is to control sources of contaminating bacteria.

Should I water my mycelium?

Mushrooms are a class of fungi that require moisture to grow.

Although they can be cultivated using different methods, mushrooms are perfect for growing in the comforts of one's home.

The kind of substrate of the mushroom you are cultivating will determine how frequently you should water it. There are specific requirements for each type of mushroom. Knowing these details allows a grower to estimate how much water and when mushrooms will need it.

There are many ways to water mushrooms, such as with a spray bottle, watering can, or occasionally even, just by pouring water on them. The best procedure will depend on the climate where the mushrooms are grown.

What are the signs that my mycelium is contaminated?

It might be frustrating to find a contaminated mushroom culture. But it's crucial to develop the ability to ascertain early symptoms and take appropriate action. It doesn't necessarily indicate that your entire growth is at risk because one culture or fruiting box has become contaminated.

One of the most evident indications of mushroom contamination is discoloration. Many kinds of invasive molds have distinctive, vivid colors. The culture is probably contaminated if you notice green, blue, grey, or black patches on or in your fruiting box. You could notice some blue areas, especially where the rye forces the mycelium against the grow box. However, remember that little blue stains in the mycelium could be bruises rather than mold.

Here are some mycelium contaminations that you should be aware of:

Cobweb Mold

This type of contamination frequently results in soft rot in mushrooms, is a group of closely related mold species, and not a single species of mold. Cobweb mold is typically seen in grain spawns and monotubs.


Cobweb mold is identified by its grey mycelium, wherein a mushroom is snow-white in appearance. It typically forms wispy, white tufts that rise above the substrate as it grows in three dimensions.

Cobweb mold spreads quickly, stunts the growth of your baby mushrooms, and in some circumstances, may even stop them from sprouting. When cobweb mold comes into touch with a mushroom, the mold quickly envelops the mushroom in its soft, mildewed mycelium, resulting in a soft rot.


The chosen bulk substrate should be sterilized or pasteurized because cobweb mold spores could be present. To kill cobweb spores, it is advised to apply a temperature of +50°C or 122°F for half an hour. This action implies that cobweb molds can be easily avoided using correct sterilization or pasteurization.

The grower should maintain ideal fruiting circumstances, which include optimum temperature, fresh air exchange, sufficient humidity, and appropriate illumination. Cobweb mold spores, keep in mind, can stay dormant in the casing layer for a very long time, but as soon as there is stagnant air in the fruiting chamber, they could become active.

Suppose a colony has been affected by cobweb mold; the right course of action is to eliminate them immediately since they can affect your healthy substrates.

Sour rot

Mushroom farmers often soak their grains for 12 to 24 hours before hydrating or sterilizing them. Bacillus spp., sometimes known as "wet spot" or "sour rot," is the most prevalent type of bacterial mushroom infection.

Bacterial endospores may be heat resistant, which means they will survive the pressure cooking procedure, which is why this practice is used. To solve the problem, soak the grains all night. Essentially, soaking the grains enables any bacterial endospores to appear and begin to grow. The troublesome heat-resistant endospores eventually die out after the grains are pressure cooked to sterilizing temperatures.


In grains, bacterial contamination is dull gray, slimy, extremely wet, and resembles mucus. It is simple to detect bacterial contamination in grains by giving your grain jar a strong whiff when you suspect it is there. If your grains smell sour, as the moniker "sour rot" suggests, you're likely dealing with Bacillus spp.


The most effective method to keep microorganisms like Bacillus spp. is to soak your grains at room temperature for 12 to 24 hours before sterilizing. If the heat-resistant endospores are alive, they will germinate in this manner and become susceptible to the standard sterilization procedure.


The most frequent pests in mushroom grow kits that cause damage to the crop from spawning to harvesting are sciarid flies (fungus gnats in the family Sciaridae). They infest pins, mycelia, mushroom stems, and caps in addition to grain spawn. The surface layer of the substrate is often where the female sciarid flies lay their eggs, which, in warm weather, hatch within a few days.


Sciarid flies are tiny, grayish-black, about 1/4-inch-long insects. They have rather lengthy legs, gray wings with a distinct split vein, and long antennae.

Sciarid eggs hatch in about three days at 75 degrees Fahrenheit. They can reach lengths of 5 to 12 mm and diameters of 0.5 to 1.5 mm, while they are larvae with a black head and a yellowish-white body.

The larvae are typically observed jumping or hovering over the substrate surface. From there, pupae develop for about ten days. It then develops into an adult fly after about four days.

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