Mushroom Cultivation: Grain Spawn


Mushroom grain spawn is sterilized and hydrated grain that has been inoculated by a live mushroom culture. This step in mushroom cultivation is used to provide a high-energy food source for mushrooms to grow to their full potential, as well as to expand your mushroom culture. Grain spawn is used to inoculate your fruiting substrate (eg. M-minus and Woodlovers).


Can’t I just inoculate fruiting substrate?

The short answer is that you CAN inoculate your fruiting substrate directly, but you will have more success if you inoculate your culture on to sterilized grain first. Grains are packed full of nutrients and starches that are necessary for fast mycelial growth and larger fruiting yields. If you were to inoculate your fruiting substrate directly with a mushroom culture, the mycelial growth through the substrate would take longer and the fruiting block would produce fewer fruits and flushes. Grains also provide multiple inoculation points for mycelial colonization, with each inoculation point providing a wealth of nutrients.


Sterilized grain spawn

Sterilization of your grains is a critical step in mushroom cultivation. It is crucial to ensure that there are no other competing organisms (contaminants) in your grains before inoculation. Because grains are so nutrient-dense, they are very susceptible to contamination and the contaminants are likely to out-compete your mushroom culture. Even fast-growing mushroom species, such as Pleurotus ostreatus, will not be able to compete with contaminants and you will either have a failure in cultivation or a highly reduced harvest of mushrooms that pose a health risk. Thus, sterilized mushroom spawn is essential for a good yield and to ensure your own health when consuming your cultivated mushrooms.


Organic grain spawn

Commercial cultivators choose organic grains for their mushrooms. The reason for this is that non-organic grains can contain anti-fungal chemicals which can inhibit or reduce mushroom growth. Organic mushroom spawn provides consistent and fast growth, which is why all the grains that are sold by Myterra Labs are organic and GMO-free.


Inoculating grain spawn

There are many ways to inoculate sterilized mushroom spawn. The three recommended methods for inoculation are agar inoculation, liquid culture inoculation, and grain spawn inoculation.

  • Agar inoculation is the cleanest method for grain spawn because contaminants are very visible on agar and the culture can be confirmed as contamination-free immediately prior to use.
  • Liquid culture inoculation can be performed in bulk and can be performed with a lower risk of contamination, but the liquid culture needs to be plated onto agar a few days prior to use to ensure that the culture is contaminant-free.
  • Grain spawn inoculation is used to expand grain spawn from one bag into multiple bags. There is a higher risk of contamination if you are not adept at identifying contamination within a spawn bag, but can be very cost effective if you have this skill. It is not recommended to expand your organic grain spawn more than twice as this can result in lower yields and poorer quality mushrooms.

Other methods for inoculation include spore inoculation, which is not recommended. Although this might seem like an easy use for your spore syringes or plates, this method poses an extremely high risk of contamination, and the mushroom culture will not be consistent between spawn bags. It is well worth the effort to learn agar techniques to isolate your mushroom culture and ensure a contaminant-free culture.


Ready, Set, Go!

Myterra Labs provides fully hydrated, sterilized, organic grains to create your own organic grain spawn. Our goal is to enable everyone to successfully grow mushrooms with as much ease as possible. All our products are fully sterilized and packaged in a HEPA-filtered clean room to ensure a contaminant-free product. We also seal all our products in air-tight, UV-resistant packaging for an extended shelf life so that you can grow mushrooms whenever you want to. Thorough scientific testing has ensured that our grains are suitable for a wide variety of mushrooms and will provide the best source of water and nutrition for your mushrooms. What are you waiting for? It’s time to grow mushrooms!