Simon Cox

+ Follow
since Jul 07, 2020
Merit badge: bb list bbv list
For More
Apples and Likes
Total received
In last 30 days
Total given
Total received
Received in last 30 days
Total given
Given in last 30 days
Forums and Threads
Scavenger Hunt
expand First Scavenger Hunt

Recent posts by Simon Cox

Profitable mushroom farming was what we wanted to do when we started cultivating mushrooms in 2013. But we were not knowledgeable about the subject. I have eaten mushrooms but that was about it. ;-)

We started with oak logs but abandoned that cultivation method 1,5 year after we started. How do you choose your cultivation method? Each method comes with its pros and cons. In this blog I’m going to take you through the most common cultivation options you have when starting profitable mushroom farming.

We have experience with 4 of these 5 methods. The one we have zero experience with, we discarded from the beginning, but we touch upon it because maybe it is interesting for you.

Inoculate logs

It was said that the Chinese were the first to cultivate shiitake mushrooms [Lentinula edodes] starting a few hundred years ago. Then in Japan they developed a method of inserting wooden plugs or dowel pins [similar like the one’s Ikea are providing for assembling their furniture] that are fully grown with mycelium from selected varieties of shiitake into holes bored in oak logs. The system has hardly changed since then.

Shiitake cultivation is not difficult[1] the biggest challenge, we found, is that your learning curve takes a lot of time. That is a direct result of the cultivation method which is divided in 6 steps or cultivation phases.

There are six key cultivation phases: 1) Purchase [or grow] wooden plugs with mycelium and storing it until use, 2) preparing logs for cultivation, 3) inoculation, 4) laying the logs so the mycelium can grow through the logs, 5) submerge the logs to force fruiting, and 6) harvesting and storing the crop

In the image above of this blogpost you can see Mark going through step 2 of this process. Drilling holes in the oak logs so the wooden plugs could go in. After inoculation we had to lay the logs horizontally and make small piles of them. Then we had to wait for 1,5 year [!] before we knew if our inoculation was successful. That was the moment you could prepare the log for a first flush by submerging it in water for 48 hours.

We found that selling the logs as a whole to customers, rather than harvest the mushrooms and sell those, was, money wise, the smartest thing to do. We made a small flyer in laymen terms, to help our customers understand the process. See image below

So why did we abandon this cultivation method? The three main reasons:

* After inoculation the logs needed to be stored outside for 1,5 year in a shady place. We didn’t have that place available in our farm that was inside a swimming pool.

* The learning curve was to long. It took almost 1,5 years to figure out if inoculation was successful.

* We sold the entire log and had to transport those logs to every market we went. They are next to impossible to send by mail due to size and weight.

Bottle farm

Next up in this list of options is the bottle farm. The idea behind this concept is partly based on scientific research about what amount of substrate gives the highest yield. Unfortunately, I can’t find this research anymore, if you know where I can find it, please let me know. So, in this paper they looked into various amount of substrate to determine how big your substrate bag or container should be to get the highest yield.

If I remember correctly the result was somewhere between 0,5 and 1,5 liters. When you have a container between 0,5 and 1,5 liters, your yield [in % of weight of your substrate] should be the highest.

That is one of the reasons behind the bottle farm idea. Another idea is that you can reuse the bottles and save on plastic. But the main disadvantage is the very high cost in machinery involved. In this video[2], you can get a good perspective on the massive automation involved. The interesting stuff starts around 1:15 in the video and o yeah, the music sucks and they have some sort of mascot running around in the recording.

Based on all this machinery, we decided to not go this direction. It would be a huge investment and it looks to me that this kind of operation can only be profitable on a huge scale. Not something we aspire to. We wanted to close local loops and use waste streams for substrate.

Buy phase 2 substrate

When we started this business, we thought that all mushroom farmers produced their own substrate. How wrong we were. Most traditional mushroom farmers in the Netherlands, buy their substrate from another mushroom farmer or substrate producer. I think it’s similar in the rest of Europe. What is phase 2 substrate?

When making straw substrate for growing oyster mushrooms, there are three specific phases the substrate goes through. Phase one is to wet the straw and form a windrow. It looks like and is basically like windrow composting. Do a web search on “windrow composting” and choose images and you will see what I mean. The image below is from a phase 1 pile at a big mushroom farmer in the Netherlands.

Image: phase one substrate windrow at mushroom farmer in the Netherlands

After it has been on the phase 1 pile for about one week, the material is ready to go into a tunnel where it is pasteurized. These tunnels can take several tons of wet material per run.

Image: Pasteurization tunnel for straw with vents in the floor

After pasteurization the straw is left to cool and is then inoculated with spawn of the species of mushrooms you want to cultivate. It’s being pressed in blocks or bags and they are shipped within one day after inoculation. After receiving the bags or blocks of substrate, they incubate at the mushroom farmer who ordered them. The blocks or bags that are produced in this way, are called phase 2 substrate bags or blocks.

The part below describes the process in technical terms. It’s a quote from: Cultivation of mushrooms, edited by L.J.L.D. van Griensven

“The composting process (phases I and II together) is a very complex process which is not yet fully understood in all its details. A mesophilic microflora begins to develop in the starting material, which consists of straw, water, minerals and an N source (for exam­ple, horse manure or broiler chicken manure).

This microflora breaks down carbohydrates (in particular polysaccharides), so that heat is released. Through the decomposition of proteins, ammonia is also produced, which causes the temperature to rise, and the straw softens through the action of the ammonia. However, the ammonia concentration must not rise too high, for this would be toxic for the microflora. As the temperature rises, the mesophilic microflora is replaced by a thermophilic microflo­ra, but the decomposition continues.

Decomposition products of polysaccharides and proteins (including organic acids and ammonia) go into the intermediate metabolism. From this, new cells are constantly being formed, again containing polysaccharides (the cell wall) and proteins (the cell content).

Some of this microflora is in turn broken down again, while ano­ther part of it assists with the decomposition. The result is a constant change and a suc­cession of generations of micro-organisms.”  

Buy phase 3 substrate

Some substrate producers offer the possibility to do a large part of the incubation at their location. When you order phase 3 substrate, you get bags or blocks that are ready to pin [primordia phase of fruiting] in days after they arrived. You will pay more for these blocks, but the advantage is you do not have to wait. J Or at least very little. One week after receiving the blocks, you can expect a full harvest.

At rotterzwam we normally make our own substrate from coffee grounds. But with all the corona measurement and the lockdowns, people where working from home and certainly not working at the office nor drinking coffee at the office. Our coffee intake went from 5.500 kilo per month to almost nothing. If we wanted to keep selling mushrooms, we needed to switch substrate.

We choose to purchase phase 3 substrate. It means we have to focus on harvesting only and use the spare time we created by not making substrate our self, in finishing the always long list of chores that you have on any production site. So far, it has worked great for us, but we are eager to switch back to making our own substrate again.

Make your own substrate

Last but not least in the list is to make your own substrate. This what we have done so far. Only after the fire [that destroyed our farm] in May 2017 [3] and now with the corona measurement and lockdowns, we have resorted to buying substrate because the show must go on.

Mushroom farmers that make their own substrate, usually resort to unicorn bags or perforated tubular foil bags. This has to do with the raw material used for the substrate and the amount of substrate you make. The more you make and the bigger your bags, the sooner I expect you to switch from unicorn bags to perforated tubular foil bags.

The image above shows ‘unicorn like’ bags from SacO2 [a spin off from Mycelia from Belgium][4]. We experimented with them for our substrate, but the results were not good. They have a filter on one side of the bag, making the mycelium growth in the not filtered side, lag significant with the filtered side. My guess is that they are best for spawn and not for substrate. But at that time in our development, we were still experimenting and learning.

When making your own substrate, there are a lot of additional choices to make. Choosing your raw material[s], cleaning your raw material, pasteurization [hot or cold], high pressure sterilization, a mixing machine, a bag filler, kind of bags, hang or stand your substrate bags etc etc. We will cover those topics in a later blog post.

Making your own substrate is giving us great satisfaction. You turn waste into taste and something of use for society. And not something trivial but a necessity of life. Food! A product that fits in a lifestyle that is oriented more on plant-based proteins. Something that you and I know is going to be more important by the day.

Image: A container filled with oyster mushrooms growing on coffee substrate

We cannot sustain the current world population based on meat and animal proteins. Not even mentioning the horror we see and hear from butcheries around the world. The mushroom provides a beautiful and tasty alternative. Making your own substrate is more challenging than buying phase 1 or phase 2 substrate but it’s so much more rewarding by seeing a local material that is seen as waste, turn into taste.

Hope this helps. Let me know if you have any questions. Drop me a mail at Or start and join the conversation below this post.

This blog appeared first at





3 years ago
After working 15 years in financial services, most of the time at insurance companies, I decided it was time for a change. I no longer felt connected with that branch, the way it treats its employees and its customers. I wanted to change my occupation and do something with sustainability. But I didn’t know what exactly. So, I decided to begin with change my network. Because I strongly believe in: It’s not what you know, but who you know. That choice eventually led me to start a mushroom farm based on open source principles in the beginning of 2013. In this blog post I share with you the lessons from the period before and the first years after the mushroom farm was founded.

Change your network
Urban farming is bigger than you might think[1]. It is practiced by over 800 million people. According to my personal experience, most modern urban farmers and also the urban mushroom farmers, where not trained as farmers. Some had well-paying, but not satisfying jobs, at big companies. But most where basically not trained to be farmers. Their education teached them nothing on how to grow crops or produce food.

So how do you make that career jump to become a mushroom farmer? You start by changing your network. When I decided to quit my occupation in the financial services, I had over 700 contacts on my LinkedIn profile. Over 500 of them connected me to a branch I wanted to leave behind. So, I took on a broad range of volunteer work and board positions within networks and foundations related to the business I wanted to move towards.

Bounce your idea
I believe creation in all parts of life, so also for business concepts, goes in three stages. First you are inspired and think about an idea. Then after that idea has matured in your head for some time, you might tell a friend about your idea, that is the second stage. Then the last part is to manifest your idea in the physical world by acting on it, for example to write a business plan or to have someone make a logo. Think, speak, act.

I think [pun intended] that too much ideas stay in someone’s head either indefinitely or to long. Weather it’s doubt, insecurity, shameor any other reason that keeps you from speaking out, GET OVER IT. Share your thoughts, talk about your ideas.

A quote that is commonly attributed to Eleanor Roosevelt says:

“Great minds discuss ideas. Average minds discuss events. Small minds discuss people.”

There are many reasons to speak more about your ideas, matching this quote to become a great mind is not one of them. ;-) When you share your thoughts and your ideas, you are already two thirds on the way of creating it, making it happen. The sooner you start sharing, the sooner you will realize your project and maybe will find yourself a team member or two.

And that brings me to the next item on the list on how to start your own mushroom farm. Gather a team. When I started talking about my ideas on starting an urban [mushroom] farm in an abandoned sub-tropical swimming paradise in the city center or Rotterdam by writing a blog about it, the idea immediately got some traction. Two people responded to my blog. One I didn’t know, the other I did. With the help of them, I got access to the swimming paradise.

When I was working to create my dream of building a business model out of collecting coffee grounds from the city center and turning it into mushrooms, the place I was located in attracted a lot of people from my network and beyond.

Two and a halve months into the project my current business associate checked in with me. I had never met him before, he found my blog post about starting a urban [mushroom] farm on page 19 of Google. He was doing research on the same idea. Although his first thought was: “Damned, someone beet me to it.” He decided to meet me for a talk. He never left and after seven years he is still the best business associate I ever met.

“If you want to go fast, go alone. If you want to go far, go together.”

We run the company with the two of us, but I have seen groups of up to three founders. Why is this important? Not only is it on tremendous added value to be able to bounce ideas, but investors, generally, tend to support companies which are run by a team than those who run solo. They trust companies with multiple founders and are likely to fund them more easily[2].

Having a good team is a great way of sharing responsibilities in different areas of your company. For example, a team with skills in mushroom cultivation, marketing & communication, sales and someone with some graphic design skills are of great benefit for start ups.

Start small
It might be tempting to start big, but I recommend you resist that urge. Most successful farmers I know, started small. The biggest oyster mushroom farmer in the Netherland started with the inoculation of one straw bale. There are a lot of advantages to begin small [end even not grow to big].

The tragedy of the commons[3] is an example that specifically applies to farming of what happens when we grow too big and overexploit our surroundings. Next to that research shows that yields can reach nearly twice the yield of typical commercial vegetable farms[4].

I’m very inspired by what you can see in Cuba. There you can find that the most productive urban farms yield up to 20 kg of food per square meter, the highest rate in the world, using no synthetic chemicals[5].

By starting small you also eliminate a lot of risk involved with having a big agricultural company. Your production, marketing, financial, human resource management plus your legal and environmental risks[6] are all at the lowest level. How great is it be able to learn and grow in an environment that is not riddled with the tension that comes with high investments and loans?

Next up is to find a location for your farm. We get a lot of questions on what is cost to start a mushroom business and that depends to a large extend if you own the land that you want to start to grow mushrooms and if there are any structures on this land. It’s simple, all the money you are spending on rent, you are not earning. It will be big advantage if you own some land.

Same with the structures that might be on that land. If you have a barn or a warehouse, it might be interesting to use sandwich panels to create your growing units inside that structure. When using a basement, you need to be sure you have access to fresh air to ventilate your growing units. If you do not own any of these, we recommend that you invest in something that keeps its value over time. Something that is modular and mobile. In our experience the container is the ideal candidate for that.

You also need to take your relative location to your market and your raw materials into consideration. rotterzwam chose to be an urban mushroom farm. We grow mushrooms on a substrate of coffee grounds that we collect in the city. We even get paid to do that. Next to that we are delivering mushrooms to restaurants and we host workshops and tours on our farm. For these reasons, our farm is located in the city and close to the city center

This location means extra cost, but these outweigh the lower cost of being outside the city but further from our target audience.

Although I strongly believe in: It’s not what you know, but who you know, you need some basic understanding of the mushroom cultivation process. You will need to know how spores influence the health of the people who are interacting with the mushrooms. How to prepare your substrate and what kind of ingredients you should use. What the local legal requirements and regulations are.

How to respond to contamination with green mold, bacterial infections or fungus gnats. When we started there where hardly any trainings aimed at small scale urban mushroom projects. That’s why we decided to started sharing the stuff we learned. Some for a fee and some for free.

rotterzwam has different ways we can help you start a profitable mushroom farming business. Every year we host 5 Mushroom Master Programs in our farm in the Netherlands. For those further away and not able to travel, we have online mushroom cultivation trainings and Online Mushroom Support.

When you have decided what type of mushroom farm you want to be, you also know who your main target audience is. This is a great moment for your co-founder to step in and show sales and marketing capabilities.

We distinguish 5 types of mushroom farms. Each has a specific earning model. Rotterzwam is currently a type B1 farm and we are evolving into a type B2 farm. Main difference is a scale up in mushroom production. The type C and D have a very different target audience then type A, B1 and B2. The type A, B1 and B2 have a much easier task when it comes to reach new customers.

For us in the Netherlands, I find it easier to sell to local restaurants than to supermarkets with branches all over the country. The buyers that work for those supermarket chains and the intermediaries that operate between farmer and supermarket are always trying to get a better deal. Margins remain low in these kinds of environments where a lot of parties need to earn a living. Having a lot of small customers also makes you resistant to shocks. We found out during a fire in our farm and later in the corona crisis. We survived partly based on working on these principles.

Mushroom species
It is time to make a decision on what species of mushroom you are going to grow. The species you choose need to meet up with some requirements. It needs to be easy to grow in different volumes, have a relative short life span [fast formation of fruitbody], a relative long shelf life [so you can store them in the fridge for some time before you sell] and should be relative unknown.

In the Netherlands the oyster mushroom fits those criteria. It has a lifespan of 6 weeks that is much shorter than that of the shiitake that is about 12 weeks. It can be stored into the fridge up to 12 days, depending on the conditions in your fridge. The button mushroom [champignon] is so famous here, that people talk about us ‘growing champignons’ all the time. Not realizing that they are mixing the species with the genus[7].

We chose a species that are in the realm that are called “exotic mushrooms”[8]. We cannot and do not want to compete with the big champignon producers in the Netherlands and Poland. Next to that the champignon has a very neutral taste and misses the meaty structure and umami taste[9] of the oyster mushroom. And with the rising interest for a vegan and vegetarian lifestyle, we expect a growing demand for these mushroom species.

Cultivation method
When you have decided on a mushroom species, it’s time to look at the different cultivation methods. Shiitake for example are mainly grown on logs or sawdust. In the Netherlands there is accompany called Groene Takken[10] [Green branches] that has created a business model on selling these logs. In fact, that was the first cultivation method rotterzwam used. But these logs need an outside environment, they prefer shady areas and need to be partially buried. We could not provide that in our swimming pool, so we abandoned this cultivation method.

In traditional agriculture, oyster mushrooms are grown on straw. We picked coffee grounds instead. The yield tends to be lower when you grow on coffee, because of more contamination with green mold, but we like the idea that we get paid to collect it. This way we can afford the loss in yield.

Typically, there are three remaining options for making a container to put your substrate in. Blocks, bags and bottles. Do a web search on “mushroom substrate block” and “mushroom bottle farm” to get an idea on how this works.

The bottle farm was not feasible because of the investments involved with the needed machinery to fill, empty and clean the bottles. At rotterzwam we chose to make bags. We have created a machine for perforating the tubular foil[11] and after we have sealed them, we fill them with substrate and close with a tyrap.

Benefit society and the planet
Allow yourself to be led by the interest of this one planet we are living on. Don’t copy and paste a cultivation method from across the globe put check what is locally available. Don’t import substrate bags when you can make them yourself with some research on YouTube. Look into ways of giving your spend substrate a destination that benefits the soil. Educate your local community about the benefits of eating less meat and show how mushrooms can fit that lifestyle.

Create employment and give your employees the room to develop their skills and the freedom to discover how you can make your mushroom farm more profitable by eliminating the waste you find in every production environment[12]. Don’t forget to innovate so you can grow your business organically and help other mushroom farmers apply your insights.

Hope this helps. Let me know if you have any questions. Drop me a mail at We can always plan a call to discuss your plans and see how we can help your plans forward. I keep spots reserved in my calendar every Friday on even weeks.

Why listen to us and trust our opinion?
We started our urban mushroom farm early 2013. We have been sharing the things we have learned based on open source since the beginning. We published our first video on how we operate our urban farm on February 13th, 2014. Since then we have trained more the 40 entrepreneurs, a few 100 people visited our workshops and more than 40.000 people have learned to grow mushrooms with our Growkit.

We have survived a fire that destroyed our farm in May 2017 while our insurance didn’t cover fire. In 2018 we launched a successful crowdfunding and raised €398.500 to build our new farm. That farm has been operational since June 2019 and it is unique in its kind.

We have collaborated with several entrepreneurs and organisations over the past years. Our approach is always the same. We provide tested, verified and applied information on how to run a profitable small-scale urban mushroom farm. What we teach is also what you can see in action in our farm in the city center of Rotterdam. We continually update this information based on new insights that arise from our daily operation. That way the knowledge we share is based on what we experience and the things we run into.

The biggest and most successful urban mushroom projects in Europe, have trained with us. Among them are Beyond Coffee in Denmark, Hut und Stiel in Austria, Le Champignon de Bruxelles from Belgium and Helsieni in Finland. Will you join them by starting a mushroom farm in your city?  

This blog is also published













3 years ago