No, mushroom spawn is not the same as mushroom spores!

Mushrooms release spores in order to reproduce. A single mushroom can release trillions of tiny spores into the air in the hope that a compatible pair will meet up and land together on an inviting surface. This is the way mushrooms reproduce in the wild. In a crude sense, think of mushroom spores like the seeds of a plant. You can plant a row of the seeds from the same species of plant but you might get variations among the individual plants that grow. They are not identical to the mother plant. In mushroom cultivation predictability and control are our friends. We want to be able to exactly replicate the DNA of a strong strain of a single species. To do this we use spawn, not spores.

If spores are like seeds, then spawn could be likened to taking a cutting of a plant. We take a piece of tissue from the mushroom and grow that onto an agar plate. This grows the mycelium which we can transfer to a liquid culture. This becomes the mother culture, the mycelium of the strong species we want to grow again. We keep this mother culture and expand it onto sterilised grain, continually replicating the desirable traits of the mother strain. The end product of mycelium on grain is called mushroom spawn. We use mushroom spawn as it is a much more reliable and replicable method to grow mushrooms than using mushroom spores.

No, grain spawn is not a ready-to-grow mushroom kit and can’t be used to grow mushrooms directly from the grain spawn bag. Think of grain spawn like a carrier of the mycelium (the inoculum), or like mushroom seed - it needs to be mixed with bulk substrate, such as hardwood sawdust, before you can grow mushrooms.

If you would like to purchase a product that is ready to grow mushrooms, the best place to start is with a Mushroom Kit or our Big Block Box.

Mushroom grain spawn is used as the carrier to transfer mycelium to bulk substrate. Grain is ideal for this job as it has a high nutrient content, a small particle size, and is a media which mycelium can easily grow upon.

Once we add the mycelium to sterilised grain in the lab, the mycelium will colonise this grain over a couple of weeks. Once it’s well established on the grains you can add these grains to bulk substrate which has been pasteurised or sterilised and the mycelium will jump off the grains and onto the fresh food source - the bulk substrate.

Each grain becomes an inoculation point to transfer mycelium to the substrate. But all the mycelium is part of the same genetic organism, so it will join back up in a network of mycelium to colonise and consume the substrate - and eventually fruit mushrooms!

Unfortunately, mushrooms just don’t grow well directly off grain spawn. It’s too high in nutrients and any mushrooms that may form will be mutated and very small.

If you keep grain spawn for a long time in the fridge you may start to see some mushroom growth forming on the grains but it won’t develop into nice mushrooms.

The correct technique for best results is to mix grain spawn into a bulk substrate such as sawdust, sugarcane mulch, woodchip or straw.

If you are looking for an easy way to get started and grow mushrooms immediately, try our beginner mushroom grow kits. These are fully colonised on a proven, high-yielding substrate and are easy to grow - just mist with water and watch them grow!

Grain spawn can be used in many ways to transfer mycelium between media. You can use it for mushroom cultivation, to make more grain spawn, or to make other types of spawn such as plug spawn.

• Mushroom cultivation - mix grain spawn with a bulk substrate such as sugarcane mulch or hardwood sawdust to grow mushrooms from bags, buckets, or outdoor garden beds

• Grain to grain - you can expand your mushroom spawn by adding some to more blank sterilised grain. This is called a grain-to-grain transfer. We do not recommend doing this unless you have a high quality cleanroom and laminar flow cabinet.

• Plug spawn - you can add some grain spawn to sterilised dowels to make mushroom plug spawn for use in mushroom log cultivation. You can also purchase ready to use inoculated plug spawn for common log cultivated species from our website.

The best substrate to use depends on the mushroom species you’re trying to grow. The most commonly used substrate is hardwood sawdust as this is close to what most tree mushrooms (saprophytic species) grow on in the wild as they decompose dead and decaying wood.

You can download our Mushroom Substrate Compatibility Guide for a better understanding of what your specific mushroom species will grow best on as well as alternatives for hard to find materials.

How much grain spawn you need to use to inoculate your substrate is dependent on a couple of factors:

• What species are you growing?

• Are you using pasteurised or sterilised substrate?

• Do you have a very clean work environment? For example, are you inoculating in a cleanroom or just in the open air at your house?

Our general rule is that the better your technique and processes are, the less grain spawn you need to use. In theory, a single grain coated in mycelium will eventually colonise a completely sterile substrate, but adding many grains will colonise the same substrate much faster.

The average inoculation rate falls between 2-10% spawn weight to final weight (wet weight) of substrate.

Sterilised substrate:

For substrate which has been sterilised in a pressure vessel and inoculated in a cleanroom environment in front of a laminar flow cabinet you can use a 2% spawn rate with confidence. For example:

For a 2.5kg bag of Master’s Mix substrate we would recommend using 50g of spawn per bag.

Super pasteurised substrate:

For substrate which has been heated with steam to a very high temperature (95 degrees celsius plus) for several hours and will be inoculated in a very clean environment such as a still air box or enclosed tent we recommend a spawn rate of between 2-5%. There is still a chance of bacterial contamination present in the substrate and some airborne contamination so a high spawn rate will help give the mycelium the advantage. For example:

For a 2.5kg bag of Master’s Mix substrate that has been steam treated without pressure we would recommend using approximately 100g of spawn per bag.

Pasteurised substrate:

For substrate which has only been pasteurised, for example sugarcane mulch or straw soaked in a lime bath or hot water, and will be inoculated in the open air (any air which is unfiltered through HEPA filters) we recommend a much higher spawn rate as your risk of contamination from airborne moulds or residual mould spores in the substrate is far greater. We would recommend a spawn rate of 10% in this case. For example:

For a bucket or mushroom bag filled with 2.5kg of pasteurised substrate we recommend using 200g - 250g of grain spawn.  

These are guidelines only and you may find with your own experimentation and trials that you are able to decrease the amount of grain spawn you need to use. However, we recommend using the above as a starting point.

It is best practice to use the whole bag of grain spawn at one time. Once the bag is opened the spawn is compromised and attempting to store it once it has been opened can increase the chance of contamination even if you reseal the bag.

If you need a smaller amount of grain spawn we recommend our 1kg bags for home or hobby growers.

Store all grain spawn in the fridge at 1-2 degrees celsius if possible, but under 5 degrees celsius is fine if you only have a standard home refrigerator.

The only exception is Pink Oyster Grain spawn which can not be stored below 10 degrees celsius. Use Pink Oyster grain spawn as soon as you receive it for best results as this species deteriorates quickly.

We recommend using spawn within 3 months of receiving it for best results.

At Little Acre we make our grain spawn from Australian-grown wheat which is sterilised in an industrial autoclave. Once the grain is sterilised we inoculate it with mycelium liquid culture. Every batch of grain spawn goes through a quality assurance process to ensure it is free from contamination. It is then incubated in our purpose-built rooms and closely monitored. Once the grain spawn is colonised we keep it chilled in our cold rooms before shipping it to you. We are making grain spawn weekly so it’s always fresh and vigorous! 

Yes. We strongly recommend choosing Express Post when ordering grain spawn as mycelium in grain spawn form is more heat sensitive and can easily overheat - especially during the warmer months!

All our grain spawn is fully colonised and ready to use upon dispatch from our facility.

Not all mycelium looks the same and some mushroom species such as Lion’s Mane, Pink Oyster, Maitake and Shiitake have a more faint mycelium which can look uncolonised. Rest assured, the mycelium is present and once you add it to substrate you will see it is active and growing!

If your spawn is slightly broken up in the bag during transit this can also affect the look of the grain spawn (similar to how it may look if you break it up ready to use it during inoculation).

If you have any concerns or questions or just want us to double check your spawn please send us some photos to hello@littleacre.com.au within 24 hours of receiving the spawn and we’ll be more than happy to check it out for you!