Even though I am now growing oyster mushroom successfully every single time, when I first began I failed a bit, mostly because I was self taught relying on scattered resources gracefully shared by others all over the internet and social media.
The pain that I had figuring it all out and filling the gaps mostly due to explanation assumptions from well meaning people, naturally led me to want to put this guide together.
By simplifying things, this guide will hopefully close the gaps for you that I encountered myself when it all began for me. The goal here is really to make you grow oyster mushroom and less of a mushroom scientist!
While at first what I am sharing with you may look intimidating, if you look beyond the false intimidation and apply yourself you will gain an invaluable skill that will become a life long reward.
Some Regular Stuff about Oyster Mushroom
Oyster mushroom is edible fungi whose scientific name is Pleurotus ostreatus (I really find no need to memorize this burdensome name…just keep calling it oyster, a light name for us commoners 🙂 ).
You sure recognize what’s in the image above. You can get oyster mushroom in just about any good grocery shop and prices will range depending on your source. Compared to oyster mushroom, white button mushroom tends to cost more at retail level where most people source it for day-to-day use.
Of the two, white button mushroom is complex to grow, calling for rather sophisticated set-ups such as climate control and some properly built up facilities. This, for the most part, leaves button mushroom production in the hands of well oiled operations, inevitably impacting it’s shelf price for the consumer.
Oyster mushroom is relatively more resilient and can fight off contamination which is any grower’s nightmare. This makes oyster mushroom attractive for micro gardeners or home growers, the reason why I am showing you here how to grow it at home.
Here is a collection of what I use to grow Oyster Mushroom successfully at home
There are a few basic requirements that I use to grow oyster mushroom DIY. The good part is they are not hard to find. You probably have a good number of them lying around somewhere. I will start by showing them to you before turning to step-by-step practical steps I actually follow to successfully produce oyster mushroom….
Oyster Mushroom Spawn
What you see here is spawn. You probably don’t have this lying around somewhere! This is because it’s specially produced in a sterile lab. Unless when ready for use, spawn must be kept refrigerated in a cold room.
Spawn can be loosely understood as mushroom seed. It is in reality a collection of living cells known as Mycelium.
Mycelium which is yellowish to white in color, attaches and grows on any suitable substance called media or substrate. Without spawn you can’t grow mushroom.
 What Substrate to use
Trying to grow oyster mushroom without substrate is like trying to drive a car which needs fuel without fuel. Substrate refers to your mushroom growing medium such as dried grass, wheat straw, rice straw, sawdust, cottonseed hull and so on. It is essentially the food for your mushroom when it starts fruiting.
Substrate is just an essential part of oyster mushroom growing. Your spawn will need growing media to start what is refereed to as the colonisation process (more on this a little later).
The list is endless. It’s a whole world out there of possible mushroom growing substrates. People continue to dedicate their research lives to understanding how best to increase oyster mushroom quality or yield by focusing on improving substrate.
The type of substrate you settle for will influence your yield positively or negatively
I use slightly crushed peanut shells which works just fine for home production. I would probably use cottonseed hulls if I was doing this at a commercial scale for higher yield purposes.
In the last number of years, I have consistently used partially crushed peanut shells. In this guide I am using the same even though you are free to explore other options mentioned or not mentioned here.
It’s always a good idea, though, that as you grow confident to try out other substrate types so you are satisfied with your yield potential and settle for your favorite substrate.
You will need Baler bags
You will need a baler bag (one or more depending on amount of mushroom you intend on producing) as shown here to pack your substrate mixed with spawn. Mixing your substrate with spawn is a process called inoculation (more on this a little later).
If you don’t have proper baler bags, you could use a plain plastic bag preferably one that is transparent so you can monitor what’s going on inside during incubation. Incubation refers to a period of time when the inoculated bag is set aside for spawn to colonise the substrate.
Pasteurizing bag
If you thought your old pillow case was no good, here is some good. What you see here is a simple good old pillow case that I pulled out from somewhere around the house. You will be using this to pasteurize your substrate using hot water.
When we pasteurize we are killing the bad competing microbes that will most certainly overwhelm our spawn and cause Mycelium that is contained in the spawn to fail to spread in its effort to colonize the substrate.
I recommend use of a plain white pillow case that won’t bleach when introduced in hot water. We don’t want dyes used in cloths to drain and contaminate the substrate.
You will need heated water
You will need a water heater to produce heated water. Substrate pasteurizing water should not reach 100 degrees Celsius (212 Fahrenheit). This is to avoid destroying beneficial microbes that naturally reside in your substrate.
While a kitchen electric jug or kettle could work, you need something with a higher capacity to heat water to about 85 degrees (185 Fahrenheit). This could be a bucket heater that can be inserted into a bucket full of water. I use a simple good capacity bucket with a heating element affixed as shown.
Prepare an empty bucket
An empty good sized bucket say of 20L (6 gallons) capacity will be needed at a particular stage of the pasteurization process.
Thermometer & Hygrometer
This is optional but good to have. A thermometer and hygrometer combo will measure your atmospheric temperature and humidity respectively.
Depending on variety, most oyster mushroom will do well between 10 to 25 degrees Celsius (50 to 77 Fahrenheit) and between 70% and 90% of atmospheric humidity.
One of the reasons oyster mushroom is great growing in cool climates is that no sophisticated infrastructure is required as would be the case in very warm climates. This makes DIY home mushroom growing exciting. In my own story, since I have quite warm summers, I have been growing mushroom every winter.
However, I would still be able to grow oyster mushroom in winter if I invested in a fruiting chamber with climate control.
You will need some Methylated Spirit or Alcohol
Denatured alcohol, also called methylated spirit will be needed to sterilize your working space, which can be a counter, table or floor space. It kills any potentially contaminating microbes. You will also apply it to your hands before handling spawn and mixing it with your substrate.
If you don’t have methylated spirit you may simply use soap to wash your hands and also washing any surfaces clean that will come into contact with your spawn and substrate.
A good rule of thumb is that when preparing your bags for inoculation, put on clean clothes just to reduce risk of contaminating things.
Get a good sized box
You will need a good sized box although this will not be needed immediately.
You will need it down the road at the time of fruiting when you are ready to have the mushroom flashing (coming out) all over the place.
The cardboard box will act as a convenient zero cost fruiting chamber with controlled humidity. Alternatively, if you can achieve 85% to 90% humidity in open air, you will not need the box.
By the way, no need to buy this. Most local grocery shops would have some to give away after unpacking shelf products.
Summary of Requirements
So now that we have gone over all the basic requirements of growing oyster mushroom in terms of equipment, accessories and aids, here is a summary of it all before I take you through the practical steps necessary to produce oyster mushrooms…
Spawn, Substrate, Baler bags, Pasteurizing case, Water heater, Empty bucket, Thermometer & Hygrometer, Methylated spirit, Good sized box (optional)
Get your Substrate ready
As mentioned, the substrate or growing media that I use is partially crushed peanut shells. I partially grind it so that it can be able to absorb moisture better and remain coherent.
Take your substrate and fill it into a pillow case and tie the top tightly. Set aside.
Inoculation
Inoculation refers to the stage at which our spawn is introduced to the substrate. This is were we are setting off the acts of nature to begin. The amount of spawn that you introduce determines, generally, the speed with which you will get the whole bag colonised by mycelium.
Because spawn is a cost, commercial operations would put just enough well measured spawn to get the colonization of the substrate going. However, at home level production you can afford to be generous allowing you to cut the incubation period significantly.
Here I introduced a generous amount of spawn to my substrate my mixing the two before filling my baler bag.
Another approach would be alternating layer by layer whereby you sparingly put a layer of spawn at the bottom of the baler bag followed by a layer of substrate followed by another sparingly put layer of spawn until you fill the bag up.
Closing your Bag
Once your bag is filled to the top. Tie it with suitable thread or seal it using sellotape or packaging tape.
Proceed to pock tiny holes all over the bag using a sterilized needle (wiped using meth spirit) to allow air in and out of the bag.
Incubation
After you seal your bag and put holes in it, it’s now ready for incubation. Incubation is when we put the inoculated bag away in a dark room or place to allow the colonization to occur.
This is usually over a period of 10 to 14 days by which time everything turns whitish in color. Your incubation space should be dark. This could be under a sink, in the pantry etc.
Some people use black bags for this reason but as mentioned earlier I find it prevents you from effectively inspecting your bag as required.
Check your bag after every two days to ensure there is no contamination. When contamination has occurred, it is usually in the form of greenish or blackish mold. The bag is good for nothing when this happens and I just through away to the compost. It is also important to remove the bag from among others immediately, to prevent contamination of the other good bags.
Steps to Fruiting
Here comes the exciting part when your hard work is on the verge of being rewarded.
Fruiting is when the inoculated bag is fully colonized as shown here and ready to produce mushroom. You determine this through regular inspection of your bag.
The way to fruit is simple.
So, take your colonised bag and make out big holes in the plastic. Do not remove whole plastic, the colonized substrate will disintegrate. After making holes soak your bag in a bucket with ordinary tape water overnight (put weights to ensure the bag goes under water)
Next day take it out of the water. Oyster mushroom will start to fruit when exposed to light (not direct sunlight). Just putting it out in the open is enough even under your home lighting. It will also need correct humidity levels. For this let’s turn to our good size box that I mentioned earlier.
Fruiting Chamber set-up
We are going to use a simple cardboard box as your fruiting chamber. Get this from any grocery store or supermarket. They usually throw these away after unpacking products.
Regular brown cardboard boxes are thick and corrugated in design. This makes them absorb and keep moisture which is good for our purposes here.
Put your overnight soaked bag in the box and gently pour water in the box wetting the insides of the open box. This will start creating a localized high humidity atmosphere. You may close part of the top of the box but allowing light to get in.
If you have a hygrometer you can measure and continue to monitor your humidity in the box.
I have fruited oyster mushroom in winter relying on between 70% and 85% humidity (vs often advertised 90% humidity). Water the inside of the box splashing part of the water on the bag itself at least once a day (set a phone reminder if need be so you don’t forget this routine).
When to harvest your Oyster Mushroom
In some 2 to 3 days you will be a witness to tiny outgrowths out of your bag usually starting with the under sides as this is usually where humidity is highest.You will see these little buttons like growths known as primordia. The games have began!.
From here on you will further witness changes almost on an hourly basis. This simply means growth of the mushroom will be rapid.
You can decide when to harvest especially when your mushrooms reach a reasonable size. I won’t burden you with the science and timing of when to harvest. If your mushroom looks good to you, go ahead and harvest.
This will be your first flash. There will be two more flashes the yield going down with every harvest as mycelium runs out of food supply from your increasingly exhausted substrate.
Data collection
Using a kitchen scale, if you have one, for the fun of it you can record the weight of your yield.
On a valuable note, this is useful data in telling your production parameters. It will also inform you of how much you are saving vs grocery bought mushroom.
Furthermore, it will allow you to understand the dollar value of your mushroom viz prevailing market prices. Extend this to recording temperatures and humidity levels that work for you for future application. Data is always good to collect even if it may mean nothing today.
Compositing
Your used bags after the third flash are ready to be thrown away. Apparently, they form a good candidate for composting. You can break them and spread directly in your vegetable garden or on a compost hip for good future organic manure.
Summary Infographic
In summary all that I have shown you in this session can be understood in this simple work flow.
If you have read through everything above, you will find it easy to find were it fits in this infographic summary. Keep it safely, this is your key to understanding simple DIY home operation mushroom growing stages.
Ready made kits
In case you love mushroom but not ready to get started following these stages, you may also opt for ready made bags which are usually known as kits. When you get such kits you will be starting from the FRUITING STAGE. Everything else remains the same.
Here are some sellers of oyster mushroom kits.
