‘Grainspawn’ is just that Grain and Spawn. The grain refers to a variety of different cereal grains/seeds and the spawn refers to the mycelium that you inoculate them with. I’m going to go through the most common grain spawns that us, as mushroom growers, use.
I will preface this with a bit of reassurance. All of these will work for almost any mushroom. However, as you gear up towards a big commercial grow (1000kg+ per month) you’re going to be thinking about more specialist grain blends that companies like Amycel and Sylvan provide where a few % saving or increase in yield can make a big difference in margins.
There are 3 main types, Wheat, Rye and Birdseed. There are also many other grains that people use which include Millet, Popcorn, Sorghum, Oats and Rice. My first and foremost bit of advice to you as a hobbyist grower is to pick the grain that most common in your area. In the UK wheat is grown prolifically whereas Rye is mostly imported or grown as a niche grain, meaning a higher price.
Whichever grain you choose, give a bit of thought to what you’re planning on growing your mushrooms on i.e. straw, sawdust, coffee and mix a few spoons in before you sterilise. You want to acclimate the mushrooms to the food/environment they’re going into, allowing them to develop the required acids and enzymes for digesting the food. This makes spawning the substrate slightly less traumatic for the mycelium, meaning it will take to it faster and reduce the risk of contamination.
Birdseed Grain Spawn or WBS Grain Spawn as it is often written is a mixture of several types of different seeds. These can include Wheat, Red Dari, Split Maize, Sunflower, Millet, Peas, Beans and much more however, the bulk of the volume comes from wheat.
In my experience it is best to avoid birdseed with ‘Split Maize’ or ‘Cracked Corn’ if possible. This is because of the difficulty when it comes to shaking as it tends to go solid and bind up after soaking and cooking.
You can find it without maize, pick it out by hand or just not worry. I’ve generally found that WBS is a bit more difficult to shake in jars but is no problem in bags. This is the only real downside of WBS as a grain spawn, it has a diverse and rich nutrient profile making it very good for mushroom growing. It also contains a good level of fatty acids which are a great energy source as well as being very common and cheap to buy.
The most common grain spawn across the UK is wheat. It is readily available across the country in pet shops, animal feed stores and even in some health food shops. It has a good nutritional profile including high levels of copper, manganese, B vitamins and protein. Once prepared through soaking and cooking, the grain swells and the mycelium can easily penetrate the soft kernel. It is often referred to as WBS (Wheat Berry Spawn) easily confused with Wild Birdseed Spawn, also known as WBS.
One of the main problems I find with wheat is its habit of drying out and the bran re-hardening up and leading to slow colonisation. This is why it is important to prepare your grain correctly before sterilising. You’ll find that hydrating any grain 100% correctly is a real hit and miss process due to the differing size of the kernels. One tip I have used is adding a few teaspoons of wheat bran to the mixture before you sterilise your grain, this readily available food gives the mycelium a kick start.
You’ll find most grains contain some debris, these aren’t going to cause any adverse effects to your mushroom’s growth, however you may wash the grain before hand to ensure any dust/debris is removed before proceed. I would always recommend wheat in the UK as it is the cheapest and most readily available source of grain available.
I’d say that Rye is the most popular choice of grain in online forums. Since most of these forums are based in America you can see why obtaining rye is easier for them than it is for us islanders. We do grow rye in the UK but it’s not nearly as common as wheat and will therefore demand a higher price. You can find rye grain online, through my shop or through my ebay page here. It’s organic as this seems to be the greatest market for rye in the UK as it’s often used for artisan breads.
It shares a very similar nutritional profile and properties to wheat, sharing the same levels of high copper, manganese, B vitamins and protein. Once hydrated the only distinguishing feature is their difference in colour. Again it shares a similar problem to drying out in the autoclave, as wheat may, but you will soon develop a method of prepping grain that suits you best however, most commercial growers will simply hydrate the grain in a bag, letting it soak over 24hrs, then autoclave it so even the less than perfect grain still works well, especially if you have developed a strain of mushrooms that has enzymes fit for that grain.
Ultimately all these grains will work just the same each with their own little nuisances that you will come to love. Wait for my next post when I compare the colonization speed of several types of grains spawn.