How to Grow Oyster Mushrooms (Low Tech)




Introduction: How to Grow Oyster Mushrooms (Low Tech)


We have been introducing mushroom cultivation as a nutritional supplement and cash crop for the landless poor. Oyster mushrooms are a high yield, fast growing crop. They are known to help lower cholesterol levels and are a great source of potassium, iron and protein.

This instructable gives a low tech, step by step guide to growing both pleurotus ostreatus (winter strain) and pleurotus pulmonarius (summer strain). Oyster mushrooms are highly tolerant of variations in temperature, humidity, light levels and carbon dioxide levels, making it a great choice for first time growers.

See related instructable - How to Grow Oyster Mushroom Spawn (Low Tech)

Step 1: Materials

You will need...

Straw (the medium for growing the mushrooms in)
Containers (for soaking straw)
Plastic bags (or reusable containers for holding straw)
Elastic bands or string (to constrict bag opening)
Cotton wool (to filter out contaminants)
Barrel or drum (for pasteurising the straw)
Material liner (for holding bags within barrel)
Gas burner (for heating barrel)
Bleach spray (to clean growing room)
Spoon, gloves, clean clothes, face mask (to look the part when inoculating straw)
A growing area that can retain moisture in the air, shaded with some light
Possibly plastic sheeting (to help retain humidity & to reduce other unwanted moulds)
Mushroom spawn (see How to Grow Mushroom Spawn)
A water or weed sprayer (to increase humidity within growing room)
A thermometer and hygrometer (to keep an eye on temperature and relative humidity)

Step 2: Soak Straw, Drain and Bag

The mushrooms require a medium to grow in, in this case we will be using straw. The straw length should be approximately 5-10 cm (2-4 inches). Placing the straw in water tight containers, submerge the straw in water for 24 hours. Wash, rinse and drain thoroughly, then bag in 5 litre plastic bags ready for pasteurising.

Step 3: Pasteurise

Position your drum onto the heat source (we used a gas burner), pouring around 40 litres of water into the drum. Place a suitable platform at the bottom of the drum, one that will keep the bags above the water yet allow steam to rise. Insert a material bin liner and fill with the prepared bags of straw. Close off the bags with the liner and cover the drum with a lid. Heat the drum, steaming the bags for approximately 60 minutes. It should take around 30 minutes for the steam to make its way to the top bags (the temperature should near 95°C ~200°F). Leave to cool, removing the bags and transferring them to the growing area.

Step 4: Prepare Growing Room

The growing room should be clean and dimly lit (shaded with indirect sunlight), able to retain moisture in the air yet also provide an airflow when ventilation is needed. Plastic sheeting can be used to seal off an area to help retain humidity and to reduce other unwanted moulds and insects.

To prepare the room for the inoculations, spray a 1:20 (5%) solution of bleach along walls and corners (any area where mould might like to grow).

Temperatures of 10°C to 24°C (50°F to 75°F) for pleurotus ostreatus (winter) and 10°C to 30°C (50°F to 85°F) for pleurotus pulmonarius (summer) should be available depending on stage of growth (initial spawn run, colonisation, pinning and fruiting).

Step 5: Inoculate Bags

Before inoculating the bags of straw, make sure you have showered and are wearing clean clothes. Clean your hands with antibacterial soap or wear sterile gloves. A face mask and hair cap will also help reduce contamination (we are very dirty creatures).

Open the bags of straw and the mushroom spawn. Taking a sterile spoon, place a few spoonfuls into the straw, breaking it up and mixing lightly. As a general rule, the more spawn you add, the faster the substrate will be colonised (with 1 litre of spawn, we inoculated about 10 bags - you could inoculate more).

Restrict the opening of the bag by placing a rubber band (or cord) around the bag's neck. Taking a small piece of cotton wool, plug the bag's opening to reduce the chances of contamination and insect infestation. Leave to incubate.

Step 6: Encourage Colonisation

Once inoculated, the bags should be left to incubate. During this time the spawn "runs" (mycelium spreads) throughout the straw. The spawn run will be complete when the mycelium has spread entirely throughout the bag (the straw is then fully colonised).

Depending on the mushroom variety, humidity and temperature, this process should take between 1 to 3 weeks.

Pleurotus ostreatus (winter), 24°C (75°F) 2 to 3 weeks
Pleurotus pulmonarius (summer), 24°C to 30°C (75 to 85°F) 1 to 2 weeks

During incubation, light is not required, however, make sure the bags have plenty of fresh air.

Step 7: Monitor Bags

It is important to monitor the bags for any sign of unwanted moulds and pests. While the straw is still in the bags, you shouldn't have a problem with insects or mice. However, the best policy for fighting both contamination and infestation, is prevention. You may want to spray some surfaces to deter flies and other insects from setting up home, mesh any windows and keep doors closed.

Regularly check bags for any mould contamination and remove any infected bags from the growing area. Black mould found within the straw may indicate ineffective sterilisation. You may also notice sprouting straw and the appearance of unwanted mushrooms such as the ink cap (see pictures). Green moulds are common and can be caused by contaminated spawn (ineffective grain sterilisation), high moisture / low spawn levels and ineffective straw sterilisation. At this early stage, it is better to simply remove infected bags, as you want to prevent its spread. Up to a 10% loss due to contamination is generally regarded as acceptable.

Finally, as the bags become fully colonised, the initial stages of fruiting (or pinning) may be seen.

Step 8: Encourage Pinning

Once pinning has started, it is time to remove the substrate from the bags. Pinning naturally occurs as humidity increases, low levels of light appear and temperature levels fall. Increase the growing room humidity by regularly spraying with a water sprayer (avoid spraying directly on the mushrooms). You can also wet the floor and leave open containers of water in the room (95-100% humidity is recommended). As our climate is very dry, we only managed 60% at best, dropping down to 40%, by spraying 5 litres of water 2 - 3 times a day (even at these humidity levels a good result can be achieved). To prevent excessive CO2 levels, allow the growing area to flush with clean air before spraying. If you can, regulate the temperature accordingly.

Pleurotus ostreatus (winter), 10-15°C (50-60°F)
Pleurotus pulmonarius (summer), 10-24°C to 30°C (50-75°F)

You may notice an initial drying out of early stage pinning, as you remove the plastic. As you maintain the humidity levels this will regenerate. Keep a close eye on flies and spray when needed. If any mould is found, either remove the infected straw or the entire mound from the growing area.

Step 9: Harvesting

As the mushrooms begin fruiting, it is important to keep the humidity high (85-90% is recommended). As before, allow air to flush through the growing area prior to spraying (oyster mushrooms require a consistent source of fresh air). Temperatures can now be higher than for the initial pinning stage.

Pleurotus ostreatus (winter), 10°C to 20°C (~50°F to 70°F)
Pleurotus pulmonarius (summer), 16°C to 28°C (~60°F to 80°F)

Remember to constantly monitor for pests, such as flies and mice, as they can quickly ruin a crop. You should expect three or more crops, each taking around a week or so to mature. You may harvest the mushrooms at any size, however, once a mushroom has reached its full size, you will notice it will begin to dry, turning a yellowish colour (they taste great, even dry). When harvesting, remove the mushroom completely, by twisting firmly at its base. After harvesting a few crops, we found it helpful to stack the mounds of straw, which seemed to help increase the yield. If you find your mushrooms with long stalks and small caps, they may not be getting enough light, also high CO2 levels can also lead to small deformities (allow for more fresh air). After the straw ceases to produce mushrooms, it can be fed to livestock or composted.

Now, finally take your harvested mushrooms and create a delicious mushroom meal. Enjoy.

See related instructable - How to Grow Oyster Mushroom Spawn (Low Tech)

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108 Discussions


5 days ago

Hi Mr. rocket surgery :)

I'm a beginner and you have no idea how happy and excited I am to have come across your articles on spawn and mushroom growing.Just a couple of questions, though.Is possible to use lemon grass or banana leaves as substrate,instead of straw?Do I only need one kind or mix two kind of substrates?Having only a small area at home, can I use a plastic container box for my fruiting bags while doing the usual procedure ( leaving the lid open for fresh air, spraying the area inside, then closing afterwards)?

Looking forward to your reply.Thank you!

This one i made in my college days..


if removing the plastic bag entirely. How do you keep the straw from drying out, ( mine is in the kitchen ) I did this before and the substrate dried out very quickly, so I ended up covering it in cling film ?

1 more answer

Basically, you can do either. You can wait until your mushrooms begin to pin (they should pin and even pinning through the plastic) and then remove bag. This method will require you to keep the humidity surrounding the medium around 85-90% (keep the growing area enclosed and spray regularly, flushing with fresh air occasionally). Otherwise, you can make cuts in the growing bag where you will find the fruiting will occur. This certainly helps with regard to keeping the medium moist but I find having the entire bag removed within a humid growing area seems to help with your yield. You should get three good flushes. All the best, try some things out to see what works best for you.

hi. I too am a beginner, when the bags are in a dark room being colonised, have you put any slits in the bag so the mushrooms can escape or does this come later when you expose them to oxygen and light ? Xx

I'm a beginner here and was wondering if I would have to completely restart a different bag after the harvest or if the oysters fruit multiple times before being exhausted. Thank you for any help and tips.

1 reply

Hey there, See "Step 9: Harvesting" - "You should expect three or more crops, each taking around a week or so to mature. You may harvest the mushrooms at any size, however, once a mushroom has reached its full size, you will notice it will begin to dry, turning a yellowish colour (they taste great, even dry). When harvesting, remove the mushroom completely, by twisting firmly at its base. After harvesting a few crops, we found it helpful to stack the mounds of straw, which seemed to help increase the yield. If you find your mushrooms with long stalks and small caps, they may not be getting enough light, also high CO2 levels can also lead to small deformities (allow for more fresh air). After the straw ceases to produce mushrooms, it can be fed to livestock or composted."

All the best!

sir I'm trying to grow Sajor caju at Lucknow up. After mycilium run of 25 days I exposed bags to light and made an arrangement with cooler to maintain temp between 27 to 30 deg. 19 days are passed ,till now pinning had not occured, will the fruiting occur, pl help?


1 year ago

my name is Seyoum, I have been working on oyster mushroom cultivation. and I have so many questions, like
1 how much water I need to spray on the mushroom after growing?
2 how much air it needs?
3 how to prevent flies(tired of killing them by hand)

I am Saurabh Bhatnagar, Very recently took a days training on Mushroom cultivation.
Started doing it at home. I am able to form beds properly , with very good mycelium growth but further pinning or fruiting happens . Why?
I have room of 12 X 14 fts.. Only one portion I am using for cultivation & inoculation. Two side doors to it. One door opens in balcony & other inside the house to other room corridor. I placed 3 Bamboos in parallel at the height of 8 Fts. the area is covered with Thick gunny cloths. I pour water over it to maintain humidity. So fruiting area is about 4 fts X 10 Fts. Covered with gunny cloths one side & other side is wall. Placed at gunny cloth on the door which is opens in balcony and keep other door closed so that humidity level maintains.
Room temp. close to 21~26 degree centigrade . Humidity 60~85%
Morning --
I open the gunny cloths from the bamboos for 3~4 hrs to allow fresh air come in fruiting area. Spry very less water to all the bags.

Could you pl. guide me where I am going wrong and not able to achieve fruiting.
What r the factors effective fruiting / yield


2 replies

A week after your substrate is fully colonised you should start to see some pinning. In nature you get a drop in temperature with Spring rains, so you can sometimes (depending on your variety) place your substrate in a cooler area and then bring them back after pins start forming. Test your substrate is fully colonised and all smell the bags (healthy bags should smell sweet).

Thanks for your reply,

My problem is why after very good pinning it dry out . Heads are not grown?

spraying water 3~4 times a day to maintain humidity. Temp. is about 28~32 degrees. Guy cloth curtains ( Half or the height) are hanged near to the fruiting area. Due to gunny cloth light is very less during day times also. do I need to open tube light in the room.

Hello Mr. Rocketsurgery,

You helped me earlier also when I started growing oyster mushroom. Now, again I need your expert advice in an out of the track question about Mycelium and oyster mushroom.

Q. Is it possible to stop mushroom fruiting completely after the spawn run is complete? I am somehow trying to stop fruiting once the spawn run is complete and the bag is completely white with mycelium. Is there a way to freeze this stage? Even the pinheads should not appear ever at any temperature and in all moderate environmental conditions for fruiting. I want the process to stop and sustain at mycelium run completion stage.

Please let me know if its possible somehow. It would be a great help here.



Surinder Verma


2 replies

I got it Mr. Rocketsurgery.

Thanks for your time. :)

I will get back to again for some other help.


Surinder Verma


Oysters fruiting conditions are basically warm weather and moisture exchange. I have never tried to delay fruiting but you should be able to refrigerate (around 4 degrees) and wrap to delay pinning. Sometimes in nature, mushroom fruiting will be delayed by a month due to the colder conditions... obviously it is best to allow fruiting for best yields, delaying may lead to less vibrant growth and so lower crop yields... do some experiments and let us know how you get on.

Hi rocketsurgery,

First I would like to thank you for such a wonderfully put together instructable on growing Oyster Mushrooms. I am very much interested in growing Oyster Mushrooms for myself and eventually to sell at local farmers markets.

I am planning to start off growing in my garage in a space of 10'x10' feet or 100 sq. feet. I am concerned on the amount of spawn I should buy to last me for the summer (3 months). Websites that are selling spawns have them with sawdust bags and grain bags/jars. Sawdust bags have yields up to 1 gallon (about 5 lbs) of spawn in each bag. The jars say they can be expanded up to 1000 times their size. I am unsure of what any of these details actually mean. The website I was planning on buying my spawn was from Fungi Perfecti and their Pearl Oyster is the type of mushrooms I would like to grow.

I have read your instructables on making my own spawn and am confident that I can do that. Just starting the grow itself is my current barrier.

TL, how much spawn should I get to start a 100 sq. feet growing area?

Kind regards,


3 replies

Hi Alex,

Thanks for your message and encouragement. The amount of spawn you need really relates to how much substrate you intend to inoculate and colonise. Also, the more spawn you use the faster the colonisation of your substrate. If you buy too much, simply leave it in the fridge and this will keep well until your next inoculations. Regarding expanding your spawn by 1000 times, 1 litre of master culture should be able to produce 10 litres of generation one, 100 litres of generation two and finally 1000 litres of generation three (see How to Grow Mushroom Spawn Step 6: Inoculation Grain Spawn Transfer for more details). It is considered good practise not to propagate spawn beyond the third generation to prevent higher contamination rates. Contamination rates of 10% or less are considered acceptable. I hope that answers your questions and I wish you all the best with your growing.

Hi Rocketsurgery,

I am starting an oyster mushroom farm in the Philippines with 20k fruiting bags, im pretty sure everything is ok but i'm a little bit lost when it comes to lighting. During the night what is the lighting requirements for oyster mushrooms?

Hi there... Regarding lighting, I have never grown in artificial light but I would recommend 12hrs on 12 hrs off, much like nature provides. Hope you have great success!