Mushroom Growing FAQs

Frequently Asked Questions About Growing Mushrooms At Home

pink oyster mushroom grain spawn

Getting Started With Growing Mushrooms

As you’re getting started with growing mushrooms it’s common to have a myriad of questions. In this article we hope to answer some frequently asked questions and provide some trouble-shooting advice for growing your own mushrooms at home.

We’ll be discussing when and how to open a mushroom grow kit, common issues with colonisation, fruiting body development, maintaining humidity and storing mushroom growing supplies.

What Is Mycelium?

Mycelium is the branching mass formed from strands of hyphae. It’s this mass that is responsible for breaking down and consuming matter via the excretion of enzymes. These nutrients are absorbed and used to expand and eventually produce fruiting bodies.

Mycelium can have different appearances depending on the species of fungi. Oyster mushrooms produce thick, white mycelium whereas species like lion’s mane are much finer and less opaque.

Mycelium will provide protective qualities to the substrate similar to the layer of mould on an aged cheese.

What Is Grain Spawn?

Grain spawn is our little known secret weapon in the world of mushroom cultivation. It’s made from sterilised grains that have been inoculated with a live mycelium culture.

Grain spawn contains a lot of energy for our mycelium to consume. It’s a bit like rocket fuel for mushrooms. Once it’s added to your substrate it takes off like wild fire. 

Mother Nature works her magic using spores but in a controlled environment you need to tip the scales in your favour by using clean high-quality grain spawn so you are doing your best to ensure success.

What Is A Grow Kit?

A mushroom grow kit is a block of supplemented sawdust that has been sterilised and inoculated with a live mycelium culture in lab conditions.

It’s really simple to use and perfect for the beginner looking to learn about mushroom growing and how to maintain excellent fruiting conditions.

open a mushroom growing kit

Do I Need A Humidifier?

The short answer is no. There are a few different methods that growers can  use when starting out to maintain higher levels of humidity. The most compact, discreet and low cost method is by making a Shotgun Fruiting Chamber (SGFC). 

Alternatively a mini-greenhouse can be used. These can be fitted with a humidifier, humidity control and fan to fully automate the process or you can mist the inner walls to increase humidity levels via evaporation.

Some species like pink oyster are very tolerant to fluctuations in humidity and are great for getting started. 

How Long Can I Store A Grow Kit?

Grow kits have a relatively short lifespan. We recommend removing the mushroom grow kit from the shipping parcel upon arrival and sitting it upright, undisturbed out of direct sunlight to ensure that the mycelium is receiving plenty of fresh air via the white micron filter patch.

Usually within a few days the mycelium will have regenerated from being in transit and is ready for opening. If left unattended it may attempt to form fruit within the bag. Fruiting may be delayed slightly by maintaining the kit at a lower temperature and by returning it to the box once the mycelium has fully colonised the substrate.

The increased CO2 levels within the box with slow down the development of fruiting bodies in some species.

Fully colonised grow kit ready to be opened.

When Is A Grow Kit Ready To Open?

It’s important that the grow kit bag remains closed until the substrate is fully colonised by the mycelium. This white layer of mycelium will help protect the sterile substrate similar to the layer of mould on aged cheese.

Learn ho

w to open a mushroom grow bag with our step by step article and video tutorial in the link below.

How Long Does It Take To Fully Colonise?

When making your own grow kits it will generally take between 8 – 21 days for the substrate to finish colonising. A number of factors can influence the colonisation speed such as temperature, spawn ratio, type of substrate, level of hydration and species of mushroom. 

Sometimes you may notice small flakes of uncolonised brown sawdust stuck to the edges of the sawdust based grow kits. This is completely normal and is due to the condensation on the edges of the bag. 

Why Isn't The Substrate Colonising Evenly?

One of the main reasons for the substrate to not colonise evenly is due to uneven fresh air exchange. It’s common for the mycelium closer towards the top of the mushroom grow bag to develop faster as it has greater fresh air exchange.

For this reason it important to unbox grow kits upon receipt to ensure maximum fresh air exchange. In some cases where the top has over developed the substrate can be gently crumbled without opening the bag to incorporate the already colonised substrate with the uncolonised substrate. Each fragment of mycelium will funtion as an inoculation point.

What Is The Orange Fluid Expelled By Mycelium?

As the mycelium colonises the substrate it will often expel metabolites. This is a naturally occurring byproduct of the mycelium. It can vary in colour from light pale to deep orange. Where metabolites condense you may find that the substrate will not fully colonise due to the excess hydration. Fruiting blocks and grain spawn rarely produce enough metabolites for it to cause any complications with colonisation.

How To Grow Mushrooms
open a mushroom growing kit

Why Isn't Primordia Forming?

The fine threads of hyphae which compose the mycelium will form hyphal knots once mature and exposed to the correct fruiting conditions. These hyphal knots will give rise to primordia – or pins. The primordia will eventually develop into the reproductive fruiting bodies which we call mushrooms.

It is almost always a result of incorrect fruiting conditions if the mycelium is not developing primordia. The three primary triggers for primordial development (pinning) are light exposure, fresh air exchange and humidity.

Generally we can discard light exposure as a very minimal amount of ambient light is sufficient. Fresh air exchange and humidity are often the culprit and should be increased by more frequent misting, the use of a humidifier, or potentially placing a small fan near the fruiting  chamber to ‘pull’ air away.

Why Do Fruiting Bodies Stall?

Primordia or developing fruiting bodies will stall if the fruiting conditions are not maintained. It’s important to provide the mushrooms with fresh air and humidity during once the kit has been opened. If the fruiting bodies dry out too much they will abort. The same applies if too much carbon dioxide accumulates around them.

How To Grow Mushrooms
open a mushroom growing kit

What If The Stems Are Growing Long?

Mushrooms require fresh air exchange to produce healthy, well-developed fruiting bodies. As they grow they release carbon dioxide. This can accumulate in the fruiting chamber or grow kit causing the mushrooms to grow long and ‘leggy’ as they seek fresh air. 

At times this can be used as a deliberate strategy to grow longer mushrooms as can be seen in the production of enoki mushrooms or reishi. 

When receiving sufficient fresh air oyster mushrooms will develop short stems and large shell-like caps. When increasing fresh air exchange it’s important to be mindful of humidity levels.

What Can I Do About Contamination?

It’s important to not expose sterilised substrates to the environment until the substrate has been fully colonised by the mycelium. This layer of mycelium will provide the substrate with protection. Despite this it is still possible for pathogens to grow and inhabit the fruiting block. Contaminants will usually have their growth stunted by the mycelium and can be disregarded at this stage.

It’s not recommended to cut away contaminants as this will often lead to a greater level of contamination of the fruiting block.

Mushrooms can be consumed as normal providing that the contaminant isn’t present on the fruiting body itself.

When Are Mushrooms Ready To Harvest?

Ideally mushrooms are harvested before they have dropped the bulk of their spores to maximise the time that they can be stored. We store our mushrooms within a paper bag in the refridgerator.

Oyster mushrooms should be harvested before the caps turn fully upwards. At this point they will still be firm and full of colour. 

Lion’s mane can be harvested while young for a firmer and tighter texture or just as the spine begin to reveal themselves for a looser and fluffier texture. 


Are Mushrooms Gluten Free?

Mushrooms themselves are gluten free. 

The spawn used to cultivate mushrooms is often grown on wheat, oats or other gluten contain grains however this is not always the case. This gluten remains in the substrate and will not form part of the edible mushroom. 

We recommend the use of gloves while handling the fruiting block for individuals who cannot make skin contact with gluten.

open a mushroom growing kit

Do I Need A Flow Hood?

A flow hood is not needed for the cultivation of mushrooms. Mushrooms can be cultivated in open air when using methods that require pasteurisation rather than sterilisation.

Small batches of grain spawn, agar and even sterilised substrates such as master’s mix or pf tek can be produced without the use of a  flow hood with varying degrees of success. An open flame such as a bunsen burner can create a small updraft to work beside reducing the likelihood of contamination.

It’s recommended to use a flow hood if you intend to regularly work with sterilised substrates. This is essential for the commercial production of grain spawn and fruiting kits with high levels of supplementation.

What If The Spawn Fruits Prematurely?

Mushroom grain spawn may form fruiting bodies before it has been incorporated with a substrate. These fruiting bodies will usually remain small and abort due to the lack of fresh air exchange within the bag of spawn. 

In the name of best practice we recommend to exclude the partially formed fruits from use. The remaining grain spawn can be used as normal.

This is less relevant if using the spawn for a grain to grain transfer or to inoculate a sterile substrate using aseptic technique as the media will be fully colonised and protected before exposing to external pathogens.

What If The Grain Spawn Is Loose?

After colonisation grain spawn will knit together into a solid block. Species like lion’s mane are considerably finer and will produce a less solid block. During transit the grain spawn can come loose due to the vibrations. 

Once broken apart the mycelium will be less visable however upon close inspection there should be visible remnants of mycelium on the grain. The grains will normally be slightly sticky. Within the starchy centre of each grain the mycelium is viable and ready for use.

Sometimes the grain spawn will knit together again as it is left to sit. This is less common for species such as lion’s mane or if the spawn is more mature.

Can I Reseal A Bag Of Spawn For Later Use?

We recommend to use an entire bag of grain spawn at once to reduce the likelihood of contamination. 

Every time the bag is opened air containing microorganisms will enter and slowly develop. Over time this will increase and eventually harm the spawn or result in greater amounts of contamination once incorporated with a substrate.

If using the spawn to inoculate a sterilised substrate it is absolutely crucial that the bag remain sealed until use.

Who We Are

I’m Luke and I’m mad about mushrooms. I operate a small scale family run business located 40 minutes west of Brisbane. We’re passionate about fungi and we look forwarding to sharing our experiences with you.

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