Using Sterilised Rye Grain Bags

Using sterilised rye grain bags for spawn…

Like all things relating to growing mushrooms, using our sterilised rye grain packs to make your own mushroom grain spawn isn’t terribly difficult, but does require that users follow strict sterile working and handling practices.

For the benefit of those who haven’t done this before, we have provided a simple ‘how to’ guide on using sterilised rye grain bags. Additionally, if this is your first attempt at producing grain spawn, we have also outlined below what some of the basic phrases you need to understand actually refer to.

As always, patience is the key when using sterilised rye grain to produce grain spawn. It takes a little patience to read up on what you need to know and do, patience to adhere to sterile working techniques and patience to wait while mycelium colonises your grain. But your patience will pay off!

Things you need to know..

Sterilised Rye Grain Bags
As you might expect, our sterilised rye grain bags contain sterilised rye grain and nothing else! Sterile and optimally hydrated, rye grain is an optimum choice for producing mushroom grain spawn. The bags are heat sealed with injection ports added after sterilisation. In order to produce mushroom grain spawn you will need inoculate material in the form of liquid culture, which you provide yourself.

Inoculation – Inoculating your grain
Inoculating your grain is effectively the process of ‘seeding’ it by injecting it with inoculate material such as liquid mycelium culture.

Spore Syringes
We always advise against the use of spore syringes. Spore syringes contain mushroom spores suspended in a sterile liquid. We advise against using spore syringes because (1) it is a slower process than using liquid mycelium culture and (2) the risk of contamination is significantly higher.

Liquid Culture Syringes
You will find liquid culture syringes for almost all types of mushroom readily available online. Liquid culture syringes contain live mycelium floating in a nutrient solution. Hopefully, your liquid culture comes in a syringe complete with a sealed and sterile needle.

Colonisation
When mycelium is added to a suitable food source such as rye grain it will start to grow and colonise the grain. What this means in practical terms is you will see white growth starting to occur in the regions of the bag where you injected your liquid culture. Your grain will change appearance until it is fully covered with healthy white live mycelium. This is called colonisation.

Using Sterilised Rye Grain

Basic process

In order to produce mushroom grain spawn you need to inoculate the grain with your liquid culture. It probably helps to think of this process as ‘seeding’. After inoculation, mycelium will (hopefully!) start to form, giving the appearance of white mould which slowly spreads through the grain. This is what you want to see!

At a later stage, you can gently manipulate the bag in order to mix together the colonised grain with the remaining uncolonised grain. Once the whole block is colonised, it is ready to be mixed with your chosen substrate. Colonisation can be a slow process (multiple weeks, not days), even when the environment you store the bags in is perfect, so patience is always essential.

Before you start – Traceability

Avoiding contamination is a battle all mushroom growers face and, when it occurs, working out what caused it is very important (otherwise it will happen again and again). Sterilised grain provided by commerial suppliers is produced in strict sterile conditions and the contents have been fully sterilised to kill any possible contaminants. However, we advise to set aside your newly delivered grain for a week, leaving it at room temperature and away from sunlight. This allows you to confirm the sterility of the bag contents and will help you better trace where any subsequent contamination (if any) came from. Typically, contamination is caused by inadequate sterile working, contaminated inoculate syringes (or needles) or incorrect handling. Most contamination is visible 3-7 days after being introduced to a food source, so if you keep a simple diary of all contact you have with your grain bags you should be able to trace the cause. We will not offer replacement bags or refunds for bags that have been inoculated, so this check is most definitely in your best interests.

Step 1 – Prep

As with all things mushroom, when using sterilised rye grain bags, first clean your hands, all surfaces and all the equipment you will be using with 70% alcohol. If you have them, wear disposable nitrile gloves (and facemask if you have one). Check the grow bag is still intact. If so, you’re good to go.

Step 2 – Inoculation

Mycelium liquid culture

Next, you need your liquid culture syringe. Remove it from its packaging and attach the needle that should have come with it. Take care not to touch the needle itself. If you are re-using a needle, you need to sterilise it in a flame before use (it must be red hot) then cool it by sucking in and ejecting a small amount of liquid culture.

Wipe the black injection port on your grow bag with a sterile alcohol wipe. Gently gently shake the syringe to distribute the mycelium evenly inside the syringe. Push the needle into the bag via the injection port and inject 5-10ml of culture into the bag. Try to move the needle as you inject, to send the liquid into different areas of the bag.

Gently manipulate the bag by pulling the neck gussets apart, allowing a small amount of air to enter the bag via the air filter – never touch the filter. Make sure there is an open space behind the filter to allow air to travel down to the bag contents – more air will be drawn in naturally over time.  Do not handle the bag roughly as this can cause holes and tears to appear, especially on folds, seams and creases. It’s all too easy to get over-enthusiastic and burst the bag or dig holes with fingernails.

Store your inoculated all in one grow bag in a location where temperature can be kept constant – the exact incubation temperature will vary according to the mushroom type you are growing – and where it is out of sunlight.

Step 3 – Mixing

Live Mycelium

After one to two weeks, the first faint signs of colonisation will begin to appear. Grain bags tend to colonise from the inside out, so signs can take a while to appear – usually around 2 weeks. You’ll see white blotches starting to pop up, which will be mycelium growing.

Once it is at least 50% colonised, take the bag and gently manipulate it to break up the colonised grain and mix it with the grain that hasn’t been colonised yet. This speeds up the process. Don’t be worried if the white mycelium seems to vanish as you break it up – this always happens.

Leave your grain to incubate until the bag contents become one solid white lump, covered in mycelium. Once you’re happy this has been done, leave the bag alone for a further 5 days to ensure the very centre is fully colonised.

Step 4 – Grain spawn is ready to use..

Once your rye grain is fully colonised it’s ready for whatever you have planned for it. Whether you plan to mix your grain spawn with substrate in a container or add it to fresh grain in order to make more grain spawn, be sure that you follow strict sterile working practices at all times. Although your colonised grain is about as contamination-resistant as it will ever be, it is not bulletproof. Putting it into non-sterile containers or using non-sterile tools will always end badly!