As winter approaches, the mushroom picking season is disappearing, so today we are going to tell you how to grow the oyster mushroom whose scientific name is Pleurotus ostreatus . It is a variety very similar to the thistle mushroom, also called poplar mushroom or common mushroom, and is widely grown by companies for sale fresh. Do you know that it can be grown at home? At Gardenprue we have done it. You dare?

LEARN HOW TO GROW THIS DELICIOUS MUSHROOM IN YOUR OWN HOME

Before entering the production of Pleurotus ostreatus, let’s see a little how mushrooms are formed.

The mushroom is a type of fruitful element belonging to a group of fungi called basidiomycetes, from the fungi kingdom. The fungus, from the structural point of view, is composed of numerous multicellular filaments called hyphae that together form the mycelium. The mycelium of these fungi is found underground, sometimes occupying large areas of land. They can reproduce both asexually and sexually. It is the latter in which the sporocarp (the mushroom in this case) is generated. Only when the necessary conditions exist (generally humidity, temperature and light) does the carpophor or mushroom “come to light”. This is where our gastronomic interest in these highly desired fruits comes in.

In some cases there are fungi that need symbiotic associations in order to develop. In the world of mycology, the most common of these associations is the mycorrhiza mycos (fungus) rhyzos (root), that is, the fungus needs the roots of a specific tree to be able to develop, which makes the controlled cultivation of this type of mushroom. In Gardenprue, one of these fungi, the chanterelle ( Lactarius deliciosus ) , has recently been mentioned . Another example of this type of association is the Boletus edulis. We will talk about him in due course. Obviously the varieties of mushrooms that are grown such as Pleurotus ostreatus,mushroom, shitake, etc. they do not need these mycorrhizal associations to develop.

PLEUROTUS OSTREATUS GROWING CONDITIONS

We are going to detail below steps to follow and conditions necessary to obtain a good production of Pleurotus ostreatus . It must be taken into account that the entire process must be carried out in the most aseptic conditions possible. Sterilized (boiled) material and always operating near a flame to avoid possible contamination from other organisms.

OBTAINING THE MYCELIUM OF PLEUROTUS OSTREATUS

To obtain the mycelium of Pleurotus ostreatus we need the spore to develop, but first we have to have a spore. We can get it from the hat of one of these mushrooms , but how do we extract it? We need a surface (blotting paper to absorb the excess water from the hat) on which we deposit the hat, without the stem and cover with a container or jar so as not to create a current of air that carries the spore away. After a few hours we will have something similar to what appears in the photograph. This is called sporography.

Once the spore is extracted, we must incubate it so that it germinates and the mycelium multiplies. We need a substrate and certain conditions to be able to do it. We will need:

• Glass jars
• Cereal grain (wheat, barley, rye, rice …)
• Cotton

As mentioned above we need to sterilize the material. Boil the mason jars for approximately 1 hour. We do the same with the cereal, we cook it for 45-60 minutes without it falling apart. If this happens we will be destroying the carbon source that the fungus will use to develop. Once this is done, let it cool down to at least 25ºC. We fill the cans with the grain and distribute the spore. This can be done by dissolving it in a little water (insisting that it has to be boiled and cooled water) and adding it to the jar with the cereal. We cover the jar with cotton. Never with a lid! We CANNOT leave the culture medium without oxygen supply. We will incubate it at 25º C until the mycelium multiplies and covers the substrate.

If, for whatever reason, this step cannot be done due to lack of time, resources, etc., there are companies that sell granulated mycelium ready to be “sown directly into the substrate.”

“SOWING” OR MULTIPLYING THE MYCELIUM IN THE FINAL SUBSTRATE

Once incubated we will have to sow it or mix it with the final substrate. The substrate can be vegetable waste, sawdust, stalks, hay but the most recommended and usual is to use chopped cereal straw. We mix the contents of the incubated jars with straw with a proportion of 3% by weight. It may seem repetitive but yes, the straw must be sterilized, cooled and aired before mixing. So we boiled it for 1 hour.

After making the mixture, it is pressed and packed with opaque plastic (garbage bag). This will keep the substrate moist and prevent exposure to light. Once the mixture is made, we need the mycelium to develop and invade the substrate before entering the production phase. It is kept at 24-27ºC with 80-90% humidity.

 PRODUCTION PHASE OF PLEUROTUS OSTREATUS

At this moment we have everything ready to enter the production phase. We make about 6-8 perforations of about 3-4cm in diameter distributed over the surface of the bag. The conditions that we will need for the production phase are:

• Temperature: 11-14 ºC . If the ranges are not respected there may be consequences in the appearance of the final product.

• Humidity : up to 95% for the formation of primordia. Between 70-75% in full production . At Gardenprue we have placed the straw bale on top of some wet earth to keep it moist. The environment was sprayed 2 times a day.

• Ventilation : Moderate ventilation is required. There are concrete data but difficult to apply at domestic levels. But in case someone needs the data. 150-250 m3 / h Tn

• Light: 8-12h of natural or artificial light . If it is artificial, fluorescents are preferable. (We have used a fluorescent lamp with a programmer)

In a few days the primordia will begin to generate and in a couple of weeks we will have an exquisite production of Pleurotus ostreatus! 

It is not difficult that the first time the mycelium does not come out or become contaminated with other microorganisms. If the preparation phase is difficult for you or you simply want to go directly to the production phase, you can always go to companies that sell bales of straw inoculated and prepared to produce at the moment. At Gardenprue we have done the latter so that you can quickly see the evolution of growth and the final result.

As you can see, in 2 weeks we have obtained a production of 2.8kg of Pleurotus ostreatus ! If they are harvested and new perforations are made we can obtain second and even third productions but less numerous. It is interesting to note the rapid growth of the carpophores. On day 10, only one of the perforations showed well-defined carpophores. It only took 4 days to obtain the result that is seen in the last photograph.