In many systems steam is used for humidifying the grow rooms. It’s a good solution to keep the right climate in the grow rooms but just keep the amount of steam going into the grow room under control. Let me explain what I mean by that.

Especially on the moment just after cool down we get a lot of steam in the grow rooms for humidity to keep the right, set humidity level. That also brings in a lot more heat in the room and especially in summer period that will give extra demand on your cooling. After some time, you will see in the computer that not only the steam valve will keep opening but the cooling as well, one will bring in humidity, the other will bring it down. The result is loss of energy and not a pleasant climate in the room with a RH level variating from very high too low, due to a lot of steam used by the climate control unit. It will be more visible under the air bags, where the steam comes out, and the RH on the growing surface will be higher. The mycelium will continue to grow there, if you compare it with the rest of the room, and less pins will grow out on those spots.

By simply wetting the floor the first 3 days after cool down you can minimize the steam by bringing in the extra moisture with the wet floors. You can do that 3 times/day if needed. Watch the steam demand in your climate computer and that will tell you if you need to wet the floor.

Erik de Groot
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After the last water during the incubation in the casing soil, the grower wants the mycelium to grow onto the surface.
To ensure a good recovery of the mycelium in this period the right settings for the room climate are essential.
An RH at a minimum of 95%. A very slow air speed, if possible zero and an adequate room temperature. That room temperature should be as close to the optimum for vegetative growth as possible. That optimum temperature is 25° C to 26° C.
This means often a room temperature of around 21° as a minimum.
Then the mycelium has the right conditions to grow onto the surface.
The next question is: how high do I let it grow ?
Higher means better control of the number of primordia, so no surprises about the number of mushrooms growing out. Higher also means easier picking so a higher pick rate. Another positive experience is that clustering is easier avoided.

But the big dis-advantage of having the mycelium higher on the surface is that the climate conditions have to be perfect. The influence of the climate onto the mycelium and the primordia is bigger. So one moment of for instance too low RH means that you will lose primordia.
Deeper mycelium is also easier to stagger the mushrooms so that is an advantage too. Another point is the fact if the grower can stop the mycelium when it grows too high. Overlay as that is called makes the outgrow of primordia more difficult. They come from underneath the blanket of mycelium.

So what determines the choice?
Both ways have their pro’s and con’s.
But for me the crucial point to choose a way is the technical capacity of the farm and the experience of the grower. If you are able to stop the mycelium at all times, still create the stagger and have perfect control of the environmental conditions, grow white.
If you are not sure of all this, grow deeper into the surface of the casing soil. So grow blacker.
Generally blacker is safer.

How mushrooms grow and the yields are determined at filling. Assessing the compost and casing soil determines the final quality of the mushrooms. After this assessment, the settings are made on the filling machine. Any mistakes made at filling, will haunt you for the rest of the cropping cycle. On larger farms “growers" focus increasingly less on filling. Just a quick look at the compost and casing soil at the start, set the machine… and that's about it.

Why is filling so important?

Compost quality
Compost quality is influenced by: colour, texture, smell, temperature, hard or soft structure. How much water can the compost absorb and should you water at filling? How well will the CAC material grow? Only paying attention during the first 15 minutes of filling is not enough to get these details right. The least you can do as a grower is to be physically present three or four times at filling, to check the compost, casing soil and the filling quality. And have a chat with the filling machine operator.

The operator also has to be almost a grower; not only with an understanding of the machine, but also understanding what compost and casing soil quality is and how to handle the raw materials correctly. And not what I keep on seeing more often: filling the growing room with compost and casing as quickly as possible and not paying enough attention to the actual filling process. Sometimes the result is a whole groove along the bed because, for example, there was a piece of wood lodged in the CAC axle. There won't be any mushrooms growing there....

The operator should therefore ALWAYS stand by the filling machine and watch the machine where the compost with casing enters the growing room. The operator should look at the CAC and levelling axles. From this position, you can see what you are doing and stop the machine immediately if anything goes wrong.

Filling is the foundation of further growth. It's not simply completing a task, but also thinking about the quality of compost and casing you are dealing with and how it should be handled during filling and afterwards during growing.

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Mark den Ouden

The targets for a mushroom farm are amongst others:

• Meet market requirements
• Good quality at the lowest possible harvesting costs

To meet the market requirements the farm needs about the same amount of mushrooms every day, seven days per week. Maybe a bit more on one day than the other depending on sales. This means generally picking seven days per week.

In most of the countries picking in the weekend is expensive so the target is often to avoid that when possible, or have mushrooms which are easy to pick. To have a relatively low cost price for picking it also helps to have more or less the same amount of mushrooms per day. So the planning of the picking and the calculation of the number is pickers needed is easier. To achieve all this a good stagger of the mushrooms is an absolute must. This starts with the choice of casing soil and the way the casing is treated.

A fine structured and perfectly finished layer of casing results often in too many mushrooms and a picking period of only 3 to 4 days in the first flush. So choosing a rough casing with an open finish of the surface helps in staggering the first flush.

Then the next important tool is the fructification or pinning. Take time to cool down the room. Take CO2 and room temperature down gradually over a period of at least 11 days. In the beginning the room temperature can be kept around 20° C for about 2 to 3 days. The compost will follow after a few days anyway.

Build in steps that are the same every day and keep humidity at the setpoint required. 95% for the first 4 days of fructification and from there a drop of 1% per day. Make sure that the band is set narrow on the RH because a deviation of just 2% can cost you the staggering you need so badly. So by taking time in this period, time and money can be saved during the picking again.

Just remember, the more un-even it looks the better. And do not look for too many mushrooms.