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Mushroom Growing Guide 14 June 2022

How to Grow Oyster Mushrooms?


Choose your own substrate for the oyster mushrooms to grow on.
A good oyster mushroom substrate could be any organic material, and should contain a high enough moisture content to keep the mushrooms hydrated, and provide a nutrient-rich structure and food source for the mycelium. We recommend using straw or cardboard but you could also use: Sawdust, sawdust pellets, coffee grounds, rice or logs if growing outdoors.
The kits include a straw substrate.

(Grain spawn pictured)


Before you begin the inoculation process, make sure your hands and the work surface are very clean. Any bacteria on hands or surfaces can affect the mushroom growth!
If using straw or cardboard, you will need to pasteurise the mix before inoculating the mushrooms. The easiest way to do this is to submerge the straw or cardboard in very hot water (65°C-80°C) for 2 hours. After the 2 hours, carefully drain the substrate. A sieve may be useful! To get the right moisture content, squeeze the substrate with clean hands! You should get just a few drops of water. If you don’t get any drips, you may need to add additional water, or if there is too much water, drain or allow the substrate to dry out for longer.
The next step is to find a sterilised container. This could be a large plastic container, bucket, growing bag or a large cooking pot. Mix the substrate and mushroom spawn together thoroughly in the container. This needs to be evenly spread. If using a grow bag, make sure that there are some air holes. The holes should be 2-3cm big every 10-15cm.


The mushrooms should now be left to incubate. Choose a warm, consistently heated area of your house, that is dark. You could use a box to help keep light out.
Incubation is complete when the substrate is completely covered in white-wool like material.


Finally you can prepare your mushrooms for fruiting!
Bring the mushrooms into the light (avoid direct direct sunlight) and maintain moisture and humidity levels. To do this, simply use a sterilised spray bottle with clean water to mist the substrate / growing environment. Try not to spray the mushrooms directly. The mushrooms should also have a good air supply. The first flush should appear within 7-10 days from the end of incubation.
Harvest the mushrooms when the edge of the mushroom caps begin to flatter or turn upwards. To harvest, gently twist the mushrooms at the base of the stem, or carefully cut flush with the substrate.

How do I grow shiitake mushrooms from the log kit?

The log kits give you the chance to innoculate your own log to start the process of growing mushrooms.
The log is
NOT included in the kit. The ideal log would be from a hardwood tree, such as oak or hornbeam. It should be cut for 2-8 weeks to allow the natural fungicides in the wood to die back, but it hasn't had time to completed dry out or become infected with another fungus. You can't use rotten logs.

Do shiitake mushrooms regrow every year?
Depending on the quality of the log used, mushrooms can fruit several times for up to 8 years!

Mushroom FAQs

What mushrooms are available?

· Pink Oyster (Pleurotus djamor)
· Yellow Oyster (Pleurotus citrinopileatus)
· Blue/Grey Oyster (Pleurotus ostreatus)
· White Elm Oyster (Pleurotus ostreatus var. florida)
· Lions Mane (Hericium Erinaceus)
· Shiitake

How much grain spawn will I need?

We recommend using at the ration of 1L per square metre in outdoor beds or mulching. If growing indoors in a container or bucket then 1L would be too much for one container. We would recommend the a 100ml bag of grain spawn for smaller projects.

What is a mushroom substrate?

Mushrooms need a substrate to grow, just like plants require soil. The substrate supplies energy, nutrition and structure needed by the mycelium, in order to develop and grow into beautiful mushrooms.

What substrates can I use?

Any organic material can be used as a mushroom substrate. Straw and cardboard are recommended as they are quite common and they require little prep.
Sawdust, sawdust pellets and coffee grounds can be used to grow mushrooms indoors.
Logs can be used if growing the mushrooms outdoors.
Straw and carboard will need to be pasteurised. This can easily be done by submerging in hot water at a temperature of 65-80°C for 2 hours. This will help to kill any bacteria and create a healthy environment for the mushrooms.
Sawdust will need to be soaked in clean water for 30-40 minutes.
Coffee grounds are best to use within a day of brewing them. If left longer, there is a higher chance of mould appearing. We also recommend using with another substrate material such as straw or sawdust. For a video on using coffee to grow mushrooms, click here.
Rice can also be used, although it is slightly harder to use. It must be sterilised before using. Heat using a pressure cooker at a temperature of 120°C +.
If growing outdoors, logs are a great substrate to use. The log should be hardwood, be healthy and disease free and be 50-100cm in length and 10-35cm diameter.

Why has mould started to form in the substrate?

The incubation period is when issues start to show. If mould has started to grow, this is usually from contamination earlier on in the process. Hands and any surfaces that touch the substrate and spawn need to be sanitised to avoid picking up bacteria. The substrate also needs to be pasteurised or sterilised before using hot water to reduce impurities.
If you’re unfortunate enough to find mould amongst your mycelium, it may be time to start over but with take extra care with sanitation. Mould can stop the mushrooms from growing. The original substrate can be used as compost.

What temperature should I keep my mushrooms at?

· Blue/grey oysters are naturally grown in the UK so they prefer colder temperatures compare to other oyster mushrooms. Ideal temperature is 18-20°C
· Pink oysters are naturally found in warmer climates. Their ideal temperature is between 18°C-30°C.
· Yellow-gold oysters prefer temperatures of 18°C-30°C.
· White Elm oysters prefer temperatures of 16-22°C.

How long will the mushroom spawn last?

Mushroom spawn can degrade fairly quickly, so it is best to use it right away or to refrigerate between 1-5°C (no lower than 10°C for pink oyseters) until it's ready to be used. It can be kept in a fridge for up to 3 weeks.

Do mushrooms need light?

During the incubation period, it’s best to block out as much light as possible. When fruiting, the mushrooms require light as it signals to the mycelium that it is time to fruit. Avoid placing the mushrooms in direct sunlight as this can cause mushrooms to dry out and prevent growth.

Do mushrooms need oxygen?

Mushrooms love oxygen-rich fresh air. If inoculating in a bag, ensure that there are sufficient air holes. The holes should be spread out every 10-15cm and should be around 2-3cm big.  When fruiting, if the mushrooms stems start to narrow and extend, it may be a sign of high Co2 levels. Ensure they get regular fresh air to avoid this.

Do I have to water the mushrooms?

We recommend spaying the mushrooms twice a day using a sterllised spray bottle. We suggest spraying the inner lining of the grow kit box to maintain a moist, humid environment.

How many harvests can I expect?

This will depend on the size of substrate and amount of spawn that has been used. On average, they should produce 5 harvests, though the size of your grow may decrease with each flush.

Do you have a video on how to grow grain spawn?

Take a look at this video showing how to grow grain spawn in a bucket.

For more help on how to grow mushrooms, please take a look here:


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