Royal Mushrooms | De Doorns

Mushrooms are one of those things that I think you either love or hate. Even if you hate them, though, learning about them is pretty fascinating. They are like little umbrellas on a sunny beach day.

As part of the Media Educational trip we visited Royal Mushrooms situated in De Doorns in the beautiful Hex River Valley. We got to see all 4 stages of the mushroom growing process.

This privately owned mushroom company was established by Mr. Hannes Jacobs during 2005. What started off as an extension for this table grape farmer, in order to create sustainable workforce all year round for employees, escalated into a booming family business. Not everything fungi is harmful as claimed. It supports brain health, alleviates symptoms of neuro-degenerative diseases, provides your body with antioxidants and even improves mood & focus.

James is a mushroom grower and was our tour guide for the day. What an excellent tour guide he is with so much knowledge and shares bis passion about the humble fungi we call mushroom. He has been with Royal Mushrooms 4 years and and overall 19 years within in the mushroom industry.

Whilst most of the world’s mushroom supply comes from commercial mushroom farms, growing mushrooms is not as simple as many people believe. In fact, mushroom growing is one of the most technologically advanced and sophisticated agricultural industries in the world.

We made our way to the growing rooms to see the various mushroom stages. The whole process from spawn run to casing and harvesting is 5 weeks excluding the compost yard which is 3 weeks. One bag contains 3 – 4kg of mushrooms out of 15 – 16kg of compost. There is 2100 bags in the big rooms and 1500 bags in the smaller rooms.

Spawn Run Phase – First Stage
This part of the process takes place in the growing rooms. These rooms must be well insulated and equipped with air-handling systems to maintain temperature and relative humidity levels. The rooms are trapped with a lot of CO2 as mushrooms grow when they get more of CO2 by taking it in.

During this stage mushroom the colonisation of the seeds starts. It needs less oxygen so that the gases can start to combine in order for the compost to be completely colonised by the mushroom mycelium.

The seeds on top is the top spawn to help colonise the bag quicker. The temperature in this room is between 27 and 29 degrees to assist with colonisation of the spawn with the compost. One start to see fine wires running from the seed into the compost. That only happens when temperature is at the right place. The compost is also a bit more darker as it is in the process of colonising.

Spawn Run Phase – Second Stage
The second stage of spawn run is when the compost and the seeds have already colonised. The bags are more open. The mycelium (fine wires) have grown into the whole bag. The temperature for this stage is now between 25 and 27 degrees.

It takes 2 weeks to get to this stage. It might take longer if you are not in control of your temperatures. Some farms allow that process to take longer, however the longer the process, less nutrients you get within the mushrooms.

Fun Fact: Mushrooms are 94 – 95% water and 4 – 6% fruit body.

The droplets on top of the compost is very important and is very good nutrient water which comes out of the colonisation of the spawn and the compost.

Casing Run – First Stage
This phase is when it has already colonised and it has been cased. This is now when the compost is colonising with the soil. The mycelium have colonised with the compost and now needs to grow into the casing.

The casing layer protects the compost from drying out, and it provides a suitable micro climate for the pin head to develop. The casing layer serves as a water reservoir and therefore needs to have a high water holding capacity.

Casing Run – Second Stage
This room is filled with misters. The amount of water depends entirely on the nature and structure of the casing soil. The aim is to raise the moisture level to field capacity and to prevent water from running through into the compost.

The mycelium starts to colonise with the casing and it must never go dry. The moisture is kept in the room and must be between 80 – 90% of the moisture. Reason for this is that once mycelium is dry it starts to blodge. The mycelium will not grow and the mushrooms will start to grow underneath the soil and it will come out dirty.

The temperature in the second stage of the casing run is between 21 and 23 degrees. The temperature is coming down gradually. If the temperature is dropped too fast the process won’t work and you have to start the whole process again. The mycelium is now colonising with the casing and become one.

Pin Heading – First Stage
This is the formation stage of the pin heading. The temperature now is between 19 and 21 degrees. The gases have been pushed out and the mycelium has reached the surface of the casing.

This temperature ‘shock’ combined with the lower CO2 leads to pin formation. At this stage the humidity can be lowered, a constant supply of fresh air will encourage pin outgrow. Higher CO2 levels and higher temperatures lead to less pins developing and lower CO2 levels and temperatures will lead to more pins developing.

Pin Heading – Second Stage
The second stage is the pin heading and the more water you have in the room, the more mushrooms you will have.

The mushrooms are now at its lowest temperature of between 17 and 19 degrees. This is where one starts to see the mushroom heads. The heads will start to grow by absorbing the water.

In South Africa mushrooms are picked by hand and therefore it is a hugely labour intensive exercise employing many people in the areas around the farms.

Button mushrooms are picked when the head reaches maximum size. They are individually picked with an upward, twisting pull. The lower part of the stem is cut off with a sharp knife and the mushrooms are graded as they are picked and placed directly into the marketing containers. The brown mushrooms are harvested as closed buttons and sold as Portabelinnis or they are harvested as big open mushrooms sold as Portabellos.

It is of utmost importance that mushrooms should be handled with extreme care as they are bruised easily. Never wash them off but rather wipe them carefully.

Brown and white mushrooms are kept separate and now and then you will find a drop of the brown cultivar between the white ones and this has to be stopped completely by placing salt on top. Reason for this is that the brown ones will take away the nutrients of the white ones, they clash and you will never get full potential of the bag.

The brown ones grow more bigger than the white ones. The brown spawn is more aggressive than the white ones and they are being kept separately.

The brown ones can have more kilograms than the white ones hence them being less in the room as they only have 100 bags per room.

All types of edible mushrooms contain varying degrees of protein and fibre. They also contain B vitamins as well as a powerful antioxidant called selenium, which helps to support the immune system and prevent damage to cells and tissues.

Not only are mushrooms good for you but they are delicious too. Next time don’t be shy to add mushrooms to your next braai with friends! Yum!

Jacobs Boerdery / Royal Mushrooms: Phone 023 354 8916 or Email –

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