Frequently Asked Questions (FAQ’s)

 Below you will find the answers to a number of questions we receive a lot.

  1. How many kilos of mushroom spawn can be produced from one test tube with mother culture?
  2. How much spawn can be produced from one bag/bottle of mother spawn?
  3. How can mycelium be multiplied in a safe way?
  4. Which laboratory setup is required to produce mushroom spawn?
  5. I want to produce my own spawn, substrate and mushrooms. Can you teach me that?
  6. Can spawn be transported from Europe to other continents?
  7. How long can spawn be stored?
  8. My bag of spawn/plugs is a bit old. Will it still be okay to use?
  9. Can you guarantee a certain yield and mushroom quality for the strains you ship?
  10. Why use sterilized and not pasteurized substrates for the production of wood- decaying mushrooms?
  11. How much spawn shall I use?
  12. What are the best bags to use for substrate and spawn production?
  13. I only need a small quantity of spawn. Can I order this at your place?
  14. Can I order different quantities of spawn plugs? How do I divide large bags of spawn plugs? How many plugs do I need?
  15. Can I order a bag of any strain I like from the strain list?
  16. We want to start a community urban farming project. We intend to grow Oyster Mushroom on a substrate of coffee grounds. How do I do that?
  17. I'm planning to experiment growing on coffee grounds. What substrate mixture and which species would you advise?
  18. I want to grow mushrooms on oak logs. What is the best: spawn plugs or grain spawn?
  19. I'm a microbiologist. I have sufficient theoretical knowledge to start a spawn lab but need practical training. Do you provide that too?

1. How many kilos of mushroom spawn can be produced from one test tube with mother culture?

Depending on the set up of the spawn lab and the working hygiene: between 1000 and 50000 kg of inoculum.

2. How much spawn can be produced from one bag/bottle of mother spawn?

You will need to use more or less 0.5% of mother spawn.

3. How can mycelium be multiplied in a safe way?

Multiplying mycelium safely is very complicated, strict production and hygiene rules are essential. Depending on the scale of the production and on the kind of multiplication, the facility will have to obey to a set of hygiene rules. Multiplying mycelium for mother cultures and mother spawn requires the most strict hygiene rules. Multiplying spawn still requires very strict rules, but less than for multiplying mother spawn and mother cultures. And finally, multiplying mycelium in the form of substrates requires less hygienic conditions than for multiplying spawn.

There is no set definition as to these rules for all sizes of spawn laboratories, but in general, the larger the production and the more towards mother cultures, the more hygienic it will need to be. If you need to set up a new production unit or review your production methods, it may be advisable to follow a training in our Mycelia School. It will prove its worth many times over.

4. Which laboratory setup is required to produce mushroom spawn?

If you want to produce spawn, you will also need to deal with either mother cultures or mother spawn, which you can order from a company like Mycelia. The production of spawn must be carried out in the most hygienic conditions, with the appropriate installations and by appropriately trained personnel.

Spawn production is not the same as growing substrates or mushrooms. If you wish to produce spawn on a regular basis and for professional purposes, you will need the essential expertise. Mycelia provides individual trainings in cleanroom technology and can also assist in the design and organisation of professional spawn laboratories. For more details, click here.

5. I want to produce my own spawn, substrate and mushrooms. Can you teach me that?

Yes, you will find all information on the "Mycelia School" page on our website.

Let us place things in perspective first if you are planning to start up your production facility.

The production of mycelium is much more complicated, risky and expensive than the production of substrates and mushrooms. It is not advisable to stimulate growers to make the mycelium themselves, unless it is very difficult to buy it fresh, for example, if you live in a remote area in Africa. A much safer way to invest your money with a good return is to specialize in only one of the production steps: only growing mushrooms or only producing substrates or only producing spawn. 

There are very few professional growers that work from test tube all the way to mushroom, because it is extremely difficult. The more steps of multiplication in the same location or building, the more likely it is that infections will pop up and stop your whole production chain. Every step of multiplication increases the risk of infection and the higher up in your chain, the more dramatic the consequences. Everyone should realise this fact: each step is difficult, let alone combining all of them in one plant.

It is strongly advised to follow a training before starting up production. It pays back its investment in a very short time and saves a lot of work and frustration. Another good source of information is reading books, but they should be the right type of books. Inform yourself well and be successful.

6. Can spawn be transported from Europe to other continents?

Provided that there are sufficient precautionary measures, yes.  Spawn is a living product and must be transported cool and quickly. The transport costs are elevated and the danger of reduced quality - due to overheating and others - at arrival is not imaginary. You will find more instructions here.

7. How long can spawn be stored?

Spawn is a living product that needs to be handled with care. Details for storage : click here

8. My bag of spawn/plugs is a bit old. Will it still be okay to use?

Again, spawn is a living product and should be stored cold for not too long. But older spawn may still be fine and there are ways to test this quality.

The first question is: is the spawn packed in a breathing bag, i.e. does the bag have a reliable filtering system? If the bags are not breathing bags, the spawn is more than likely suffocated. If they breathe too much (cheap bags) they will have dried out.

Second question: does the spawn look and smell good? If the bag is full of brown, stinking liquid, the material is decaying and should be discarded. If it is clear, non-odorous, yellow liquid, it is a sign of age, but it may still be active enough.

How do you test your spawn/plugs? Take a sample from each bag you wish to use. Take a clean (!) plastic container, put a pile of wet paper (toilet paper, kitchen paper) and put the spawn/plugs on top of the paper in a warm but shady place. The mycelium should be visibly growing into the paper in a matter of days. If it hasn't done anything in - say - five days, discard your spawn/plugs. It may still be active, but old spawn is slow and it's better to be safe than sorry.

There is an even better way to test your spawn/plugs: use sterile petridishes with a rich medium, for example malt extract agar with dextrose, open the lid as little and as fast as possible in a clean place or under an LAF and put a few kernels onto the dish. Close the lid and roll the kernels around a bit to spread the mycelium. Put it at 25°C. If white mycelium filaments are visible at the edges of the grains/plugs in a matter of 3-5 days, your mycelium is still active and is fine. If it starts growing after 1-2 weeks, it is getting old. If it doesn't do anything after 2 weeks, discard the spawn/plugs.

9. Can you guarantee a certain yield and mushroom quality for the strains you ship?

Our technical data sheets (see strain list) are a compilation of data provided by customers from different regions. It is a general rule in mushroom cultivation that the results entirely depend on the way you treat the mycelium:

  • type and treatment of substrate
  • type of bag (gas exchange is extremely important for Shiitake!)
  • quality of spawn at the time of inoculation
  • inoculation rate
  • situation (temperature in the first place) in the incubation/ maturation rooms
  • climate control during fructification
  • and a number of other factors also influence the yield and aspect of the mushrooms

As a result, it is impossible to "guarantee" yields or the efficiency of any form of substrate transformation.

10. Why use sterilized substrates for the successful production of wood- decaying mushrooms?

One can distinguish two groups of cultivable mushrooms:

1) Compost mushrooms, such as Agaricus bisporus, are cultivated on Agaricus compost, a selective substrate on which almost no other microorganisms can grow. If one uses impure spawn, yields may decrease, but one will still be able to pick mushrooms.

2) Lignicolous mushrooms, to which group belong most exotic mushroom species, are cultivated on wood-based substrates. For a number of species, the substrate has to be sterilized and subsequently inoculated under cleanroom-circumstances. For this kind of production method, the substrates should be 100% axenic, else everything fails. Other kinds of lignivorous mushrooms can be inoculated after pasteurization, but this requires larger amounts of spawn.

11. How much spawn shall I use?

1) Compost mushrooms : 0,35 % (Fresh Weight / Fresh Weight).

2) Lignicolous mushrooms :

            sterile production : 0,5 to 1 %

            non-sterile production : 2 – 7 %, depending on the strain: see strain list

3) Logs: Depending on the log diameter and personal inoculation style. Estimate: 5 liters of spawn/ton of wood.

12. What are the best bags to use for substrate and spawn production?

There are a number of qualities a good spawn bag needs to have.

  • breathability: the bag needs to breathe without letting contaminants in
  • durability: the bag needs to be sufficiently strong to survive manhandling
  • heat-resistance: the bag needs to be sterilizable or pasteurizable, which puts limits to the construction material
  • size: there needs to be enough space inside, without it being too large
  • price: as most spawn bags are meant for single-use, the price should be as low as possible
  • ecology: the bag should produce as little waste as possible

NOTE: There are many types of receptacles on the market, from bottles over containers and vessels to bags. There is no set rule as to which receptacle is best to use, although most professional spawn growers use bags.

Our sister company, SacO2, produces very high-quality spawn and substrate bags with a full fiter system, which are specifically designed for usage in the mushroom sector. These are the most uniformly breathable bags on the market, which gives them a serious advantage in terms of quality.

13. I only need a small quantity of spawn. Can I order this at your place?

Certainly, we also sell for hobby and educational purposes. Considering man hours and transport costs, it is more expensive than larger quantities, but it will most likely still be the best deal you will find anywhere.

14. Can I order different quantities of spawn plugs? How do I divide large bags of spawn plugs? How many plugs do I need?

We produce two standard volume-weights of plugs: 50 pieces and 1000 pieces per bag. We can make other quantities, but only if we can make at least 100 pieces. We do not produce other amounts on a regular basis, as most clients of us are either hobby growers - for whom 50 pieces is enough – or professional growers.

Professional growers:

  • inoculate substrates with bags of 1000 pieces
  • divide bags of 1000 pieces into smaller unities

Dividing bags into smaller unities is best done under sterile air conditions, i.e. a laminar air flow LAF. In that case, one can divide without contaminating the spawn plugs.

Another perfect solution is splitting the 1000 plugs within the bag while the bag is still closed into for example 2 piles of 500 pieces. Next step is to seal between the two piles twice. Then cut the bag between the two seals and you have two bags of 500 pieces each. Watch out: each new bag should have at least one filter strip.

If you do not have a sealer, you could also do it as follows: split the 1000 plugs within the bag while the bag is still closed into for example 2 piles of 500 pieces. Cut the bag between the two piles. Tape off the cutted edge of both bags. Watch out: each new bag should have at least one filter strip. There is a little more risk this way, but plugs don’t infect easily so it’s more or less fine. Just try to do it in an area which is as clean as possible, which has no moulds, compost bins or rotting fruit nearby and keep the bag open for as short as possible.

Finally: keep the plugs at 2-4°C until you need them and you will be able to keep them for a long time – up to 10 months and even more for some species like the Shiitake Mushroom.

How many plugs do I need?

That would depend on the parameters of your logs. You will need to estimate the circumference of your logs, considering that you want to have the holes about 15 cm apart. Slender logs need less plugs than thicker logs. There is only one way: measure, calculate and estimate. Every large bag of plugs contains 1000 pieces.

15. Can I order a bag of any strain I like from the strain list?

We don’t produce ‘one-off’ bags, as we have to finish a mother spawn bottle or mother spawn bag once it has been opened for spawning. This means that we only produce spawn in quantities of 20 liters or more, depending on which bags are being ordered (5-liter bags, 1-liter bags or 10-liter bags have different minimum production quota).

There is one exception to this rule: we commonly produce many kinds of spawn, which means we often have bags left over from previous orders. You will need to contact us to know which types of spawn we have available.

From april 2015 onwards, the minimum order limit at our plant is 20 litres of any type of grain spawn or 4000 plugs/sticks. 20 litres is one full box in summer (in winter, one full box can contain up to 25 litres). We allow smaller orders for our existing customers. Contact us if you have any questions about these sales.

Due to internal reorganisation, Mycelia has decided to redirect its hobby sales. The combination between large scale production and small scale orders has always been a delicate balance and we are now looking at supplying hobby growers through a network of local spawn distributors instead of directly through us. Click this link for an overview of our partners.


Our Belgian customers are redirected to:

Berendries 13 a
0496 30 42 35

Vaart Linkeroever 90
9800 Meigem (Deinze)
09/385 71 49

16. We want to start a community urban farming project. We intend to grow Oyster Mushroom on a substrate of coffee grounds. How do I do that?

Urban mushroom farming is very interesting indeed. The idea is basically that coffee grounds are already thermally treated (pasteurized) and can thus be inoculated and incubated without any extra treatment. It can be done by anyone at any time and it can be done almost eternally in any urban residence. This method only works for fast growing species, of which Pleurotus ostreatus is your best bet: it's tasty, beautiful and the spawn is relatively cheap and easy to get.

It's a great idea, but there is a big BUT which you will not find on the internet. The internet is a great thing, but it only shows the shiny side of the coin. The reality, however, is never that shiny.

What's the BUT?

The coffee grounds come out of the machine thermally treated. So far, so good. Above 65°C, all fungi and fungal spores die, only thermophylic bacteria survive. If the coffee grounds would be cooled down, inoculated immediately with good spawn in a clean place by clean people and subsequently incubated in a protected environment (usually a plastic bag), all will be well. The bag will grow white and yield magnificent mushrooms.

Trouble is, it is usually not done this way. It is used in bars by bartenders, collected and transported to a 'clean' place by someone, where it is mixed by the same person in the same clothes and then inoculated in the same room by the same person and then incubated, again by the same person. Almost anyone trying this method is succesful at the start, but after a few tries problems pop up. One or two bags are green... a green mould instead of the white Oyster Mushroom colour. The week after, 5% of the bags are green, the week after 15% and the next week, almost 100% of the bags are infected. In fact, over a couple of years of seeing people trying this system, most have been succesful initially, but not even a single one has been succesful for an extended period of time, including the advertising enthousiasts on the internet. Why?

The reason is simple.

The coffee grounds are used by the bars, pubs and restaurants and they are left to cool down in an open container and are picked up in the evening or even a day after. By that time, they are already reinfected by fungal spores. There are millions of fungal spores floating around in any bar or pub and they fall down and germinate wherever they can. The whole purpose of the thermal treatment is in fact lost. Because what happens? This batch is taken to the mixer or drainer, is inoculated, closed and moved to the incubation room. One bag may turn green. This green colour indicates that the green mould has overcome the Oyster Mushroom mould and that it is sporulating; it is literally producing millions and millions of spores. That means that the air of the room where this bag is situated will now contain millions and millions of spores, all floating around. If you open and close the doors of this room regularly, all adjacent rooms will soon be teeming with spores as well. They will attach themselves to all bags, racks, windows and lamps, to the people working there, to anything.

When making your next batch, rest assured that some of these spores will find their way to your new load of coffee grounds and infect them. 5% of the bags turn green. Next batch, the spore load has increased manyfold and 15% of the bags are lost. In the next batch, the spore load has become astronomical and nearly 100% of the bags are lost. This is a simplification of the reality, but it is basically what happens.

The green moulds are fungi too and their mycelium is more aggressive - i.e. it grows faster - than the Oyster Mushroom mycelium. If they are allowed to start growing simultaneously with the Oyster Mushroom, they will win. They should NOT be present. When the bag is fully grown, they will not stand a chance against the Oyster Mushroom, but at first, they are stronger.

So be aware of this: the internet story is beautiful, but in the long run, it is almost never successful. There are companies that produce Oyster Mushroom grow kits on coffee grounds on a continuous basis, but they obey a few basic rules:

1. Your substrate - coffee grounds - are partially infected when they reach your place. Know this as a fact. If you don't thermally treat it before inoculation, you will always lose a number of bags to competing moulds (green, orange, black, white, yellow, etc). Sometimes the Oyster Mushroom mould will win, but don't count on it too much. These moulds will present a danger to your production chain. Spores are typically 5-15 µm in diameter, so individual spores are not visible to the eye.

2. Your people, the ones that do the job, are the most dangerous elements in any mushroom production facility. People carry around millions and millions of spores around with them at ANY time. Washed clothes and washed hair is better than dirty clothes and hair, but it is NEVER clean. Workers handling fragile parts of production such as inoculation and incubation should carry adapted clothing, which should be constantly treated (single use or heat treated) and they should never roam from place to place, especially never from mushroom growing rooms to incubation or inoculation rooms or back. People working in inoculation should be as contaminant-free as possible. Covered body,  hair, nose and mouth and hands are essential.

3. When you inoculate and the environment is not sterile, you will infect the bag. Know this as a fact. You will always lose a number of bags to moulds. There are ways to avoid this, of which inoculating in front of a laminar air flow (LAF) is the best. It can be home built and is not necessarily very expensive. The second good solution for keeping your air clean is to have an overpressure system which constantly blows overpressurized sterile air in (some of) their rooms. These are the two best proactive solutions.

4. The most important defense against mould trouble is HYGIENE. Cleaning with desinfectants is an absolute must if you want to produce mushrooms on a continuous basis. Desinfectants never kill all spores and bacteria, but they do a good job. Getting rid of all dirt (especially nutrient-containing dirt like rotting mushrooms or grains or so) is of utmost importance. So: cleaning, cleaning, cleaning. Every day for the inoculation room and associated tools and machinery.

5. This list would not be complete if the layout of your mushroom/substrate farm weren't included. The position of the doors, the usage of drains and taps, the building materials, the place of the sluices, etc. All these are essential if your production is to be continued. When material is moved from one place to the next, this is done by people. The so-called product flow and people flow will determine which air masses will get moved/mixed and which won't. It will also determine which people should work where at what time. All workers should know and obey these rules.

If you're only aiming at a temporary production of - say - two or three weeks (= pop-up mushroom farm), then you will never build up a spore load. In fact, in that case, you might as well inoculate in a kitchen sink, as clean as you can but without any investment. All above rules are to be seen in case you wish to have a continued production for a certain period of time. If you're planning to make a limited number of bags over a limited number of time, we would suggest to keep it simple:

- accept some losses (it should never be more than 5%)

- don't inoculate in the same rooms as you mix and drain your substrate

- keep the inoculation / incubation room as clean as possible, cleaning every day you inoculate

- use bleach as a desinfectant, 5% of a 14-15% solution will do

- clean surfaces, floors, racks etc.

- clean your mixer/drainer regularly

- work in a clean place. Don't make spawn in the basement of a pig farm for example.

- keep your spawn in a clean refrigerator 2-4°C for no longer than 2 weeks - 1 month to keep it fresh and aggressive

- don't use coffee grounds that are old, make sure the bartenders keep them as clean as possible. Give them plastic bags that they should immediately seal when they switch off the coffee machine etc. Any measure reducing the exposure time is great. Thermally treat (pasteurize) your grounds before inoculation if you can, this will spectacularly improve your quality and reduce the risks manyfold. You could dunk the substrate in boiling water and then drain it for example.

- give hair, hand and mouth/nose protection to your workers and tyvek overalls if you can afford them during inoculation. Use the only once or wash and thermally treat them after use.

- seal the bags just after inoculation

- shake the bags just after sealing, it will increase growing speed and reduce the time the bag needs to grow white. Less time = less risk. You can seal by taping the bag.

- don't think a pilot project should necessarily give the same results as a continued project... mushroom growing doesn't work like that

17. I'll start growing mushrooms on coffee grounds. What substrate mixture and which species would you advise?

There are still a lot of unknowns in the field of growing on coffee grounds. If you are looking for the ideal recipe: we do not use coffee grounds in our recipes ourselves, so we don't have this information available at the moment.

Regarding the species: keep in mind that most cultivable (specialty) mushroom species are lignicolous mushrooms, meaning they are wood-loving. The mixture will need to contain wood or wood products like non-contaminated sawdust of deciduous trees to allow the mushroom to grow properly.

Most people that experiment with coffee grounds work on pasteurized substrate. Most lignicolous mushrooms are grown on sterilized substrate, but there are a few exceptions:

  • all Pleurotus species are extremely aggressive, so they usually do quite well on pasteurized substrate.
  • Stropharia sp. can certainly be grown on pasteurized substrate, see our instructions for use for more information.
  • Agrocybe aegerita and Hypsizygus tessulatus are also grown on pasteurized substrate, but it is much harder than Pleurotus sp. There are even substrate producers that inoculate Shiitake on pasteurized substrate but don’t try this at home, it is not easy.

If you are not an experienced grower yet, start off with Pleurotus sp. and Stropharia sp. or if you are really keen, with Agrocybe aegerita. They are fast growing species, although Pleurotus is definitely the quickest. Species like Stropharia and Agrocybe grow slower than Pleurotus, which means you will have to work cleaner and better. You will also have to spawn more than you would Pleurotus.

18. I want to grow mushrooms on oak logs. What works the best: spawn plugs or grain spawn?

Both are effective and efficient.

Until a number of years ago, nobody used spawn plugs. All growers made cuts in their logs and put spawn in it. The cuts were taped off and the log was wrapped in plastic. The tape is to keep the mice out. The tape simply falls off after a year. It is essential to keep the logs wet, for example by wrapping them in plastic. The method is still widely used and works perfectly, it is easy to do and is very efficient, but spawn only keeps for a number of weeks in a fridge.

Since a number of years, many people use spawn plugs. they are easy to handle, it is just as easy to do and efficient and spawn plugs keep much longer in the fridge (up to over a year if you're lucky). The holes are drilled, the plugs inserted, the logs wrapped in plastic. Some people seal the holes with wax afterwards but to our practical experience, that's not too important if the holes have the correct diameter for the plug (it should be a nice, tight fit). It is on the other hand very important to keep the logs wet, for example by wraping them in plastic. Essentially, the system hasn't changed.

There is no better or best, the choice is entirely yours.

19. I'm a microbiologist. I have sufficient theoretical knowledge to start a spawn lab but need practical training. Do you provide that too?

Sure, we offer practical training, but it is always mixed with theory. With theoretical knowledge, we also mean things like machinery, sterilisation procedures and sterilisation curves, spawn quality control and measurement, etc. Our section ‘microbiology’ is extremely short: about 1,5 hours on the totality of 3 days of training.

When you have the theoretical background about microbiology, you should know exactly what the difference is between a fungus, an algae and an amoeba, how they reproduce, on what type of agar they grow, how to conserve them, how to inoculate agar plates, etc, which is extremely helpful. All our staff involved in the essentials of spawn production has had a degree of schooling in microbiology. But, even with this background, you must understand that starting a spawn production unit is a completely different thing.

At university, they don't teach you how to make the difference between a good raw material and a bad raw material or how to source them, how to practically sterilise larger quantities and monitor and computerize the process, all the while keeping it as cheap as possible, how to inoculate larger quantities quickly, etc. It takes about two years to fully understand the production process.

Please do not take the transition from academical microbiology/mycology to practical spawn production lightly. It is not the same. The more you wish to produce, the more important the difference will become. If you intend to produce 20 litres of spawn weekly, don’t bother following a course. But if you’re intending to do more than that, you’ll find it to be very helpful.

We do not wish to exaggerate, but we reckon a spawn production training is worth its value. At Mycelia, we have a company policy to be open to our trainees. We physically train them in our own production facility in Nevele, both in the spawn and mother spawn department. We allow pictures and videos to be taken home. We have as an objective to train the attendants to run their lab successfully and this is what we do.


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