Growing Mushrooms at Home: Substrates & Grain Spawn

Identifying the Best Substrate

At-home mushroom growing is taking off like never before. Whether you are looking to grow edible mushrooms, functional mushrooms, or medicinal mushrooms, NANO has various substrates and an array of information to suit your needs and guide you along your at-home mushroom growing journey.

For example, oyster mushrooms may thrive on straw substrate whereas Lion’s Mane and Shitake mushrooms grow best with a hardwood substrate.

Understanding the substrate that will best serve your purposes is dependent upon the types of mushrooms you are planning to grow.


Utilizing a grain such as rye as a substrate is seen commonly in the cultivation of medicinal mushrooms such as P. Cubensis.

Grain is used as a high-nutrient medium for rapid mycelial expansion. It is typically the step after mycelial growth on an agar medium.

Rye is typically considered the best go-to grain for growing mushrooms because of its small kernel size which means more total surface area for the mycelium to grow out of when it is placed into a bulk substrate. It also holds more moisture than any other grain and rarely bursts or gets mushy.


Wheat berries are another great choice and are very similar to rye, however, they tend to break when processed and don’t hold as much water.


Millet is great to mix with another grain to make grain spawn. It’s the smallest grain, and thus provides a massive number of different inoculation points in your substrate. Check out NANO Fungi Sterilized Millet for the best-priced and highest-quality millet for your grain spawn needs.

What is Grain Spawn?

Utilizing grain spawn provides a major benefit by supplying a pre-colonized Nitrogen source to the substrate.

Grain spawn provides an advantage in the world of mushroom cultivation because of its ease of use as a starter culture to grow mushrooms.

It’s made from sterilized grains that have been inoculated with a live mycelium culture. The growing mycelium consumes the inoculated grains which are a huge energy source and provide an ideal nutrient profile.

These inoculated grains are consumed by the growing mass of mycelium and are mixed with a bulk substrate.

Why Is Grain Spawn Sterilized?

Grain is an excellent source of nutrients for mycelium because it is packed full of starches and sugars. Grain spawn must be sterilized because while it’s an amazing food source for mycelium, it’s also an ideal growing medium for mold and bacteria, a major contamination source. Due to that, the grain must first be completely sterilized to ensure that any mold spores or bacteria have been killed off.

By utilizing a pre-sterilized grain such as NANO Fungi’s Sterilized Millet you can be assured that you are utilizing the highest quality grain for your at-home mushroom grows.

If you choose to make your own grain spawn, be sure to check out our upcoming article “How to Make Grain Spawn for At-Home Mushroom Grows” and check out NANO Fungi Wide Mouth Jar Lids w/ Rings, and NANO Adhesive Air Exchange Jar Lid Filters which you will need if you are planning to make your own grain spawn.


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Join our email list and keep up to date on new developments. *All NANO articles aim to provide well-established scientific information paired with up-and-coming research that can be used as a starting point for further exploration and in making empowered decisions to improve all aspects of your health and life. As always, we encourage you to continue along an enlightened path by doing your own research, thinking critically, and trusting your intuition. All content on this NANO site is for informational and/or educational purposes only and does not substitute for professional medical advice or consultations with healthcare professionals.

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