What is the Best Substrate for Mushroom Spawn

When it comes to magic mushroom cultivation, there are certain things that you would need to know to harness high-quality shrooms for your consumers. Seasoned growers of magic mushrooms know that substrates are one of the basic aspects of mushroom cultivation. It is an essential part of providing nourishment to the mushrooms which in turn grow and provide a very potent effect to the users.

But, what is a substrate, and which is the best substrate for mushroom spawn? Learning how to grow magic mushrooms takes a lot of time and effort and knowing which substrate is best for your mushrooms is an essential task for a grower.

What is a Mushroom Substrate?

A mushroom substrate is a collection of different organic materials that are used to provide nutrients and energy for the mushroom spores to grow into full-blown mushrooms. A good mushroom substrate can provide all the needs of mushroom spawns until they grow and fruit. They are prepared through different methods and each method would result in a different mushroom substrate.

These substrates are prepared differently and undergo strict sterilization before they are introduced to the spores. The reason behind the strict sterilization process is to prevent contamination of bacteria and other types of fungi that may cause harm to the mushrooms. Any form of contamination would risk affecting the growth and overall potency of the magic mushrooms.

Other factors alter the way substrates work with mushrooms. Temperature, humidity, sunlight, air circulation, and many others can affect the quality of your substrate. For that reason, placing your mushrooms substrate in a controlled indoor environment is key to the overall management of your mushrooms.

Some of The Best Substrate for Mushroom Spawn

When it comes to using the best substrate for the mushroom spawn, it all depends on the resources that you have. However, here are some of the most common and effective substrates to breed the mushrooms.

  1. Straw

Straw is considered one of the most common materials used as a mushroom substrate. Not only is it cheap to acquire, but it is also almost everywhere. You can simply purchase them in your local farm or even get them by yourself if you have your farm. While it is considered as a waste product for farmers, straw is a brilliant substrate for mushrooms spawns.

However, one of the main drawbacks of straw is that it needs to be prepared intricately first. It needs to be cleaned, chopped, and then pasteurized before it can be used as a substrate. While it can be complex for beginners, it is commonly used in large scale operations for its availability and effectiveness to do its job.

  1. Compost

Another effective substrate that you can use for magic mushroom cultivation is the use of compost. These can be made of fruit and vegetable scraps to coffee grounds. The mixture of all these organic materials is highly recommended. They provide the best mix of nutrients, water, and minerals for the mushrooms to grow well.

A compost substrate would mean a healthy organic dose for your mushrooms but you also need to be careful with the materials you use for the substrate. These products are readily biodegradable and often attract bacterial growth. This is where sterilization comes in and even then, it can still be risky to produce mushrooms using this type of substrate. Usually, this type of substrate is used by seasoned growers.

  1. Coco Coir and Vermiculite

Coco coir is a mix of coconut husk and the shells. It is commonly used as materials to grow mushrooms due to its ability to retain moisture. With its rich organic materials, coco coir provides all the necessary nourishments for the mushrooms to grow.

Many would want to simply use coco coir alone however, the moisture and the nutritious organic substances can still attract pests and bacteria which can destroy your mushrooms. This is why vermiculite is added into the mix and then pasteurized after so that it can still retain the moisture and allow the mushrooms to proliferate without having to deal with contamination.

  1. Manure

Animal manure is a common material used as a mushroom substrate. While there are only a few types of magic mushrooms that grow steadily in a manure substrate, it is still one of the most effective substrates to use for mushroom cultivation. The manure is gathered and undergo days of composting before it is mixed with straw. The mixture is then exposed to heat so that certain organisms thrive to give the mixture an extra boost of nutrients.

This compost undergoes pasteurization process to remove the harmful organisms while retaining the good ones. Another round of pasteurization then happens but this time, it removes the ammonia and other chemicals that can bring potential harm to your crops. While this is a complicated and tedious process, using manure as a substrate is not recommended for home growth. It is usually done by large scale mushroom growers who have all the equipment to mix and pasteurize the compost.

  1. Hardwood Sawdust

The use of hardwood sawdust is one of the best, most common, and most economical means of producing a substrate for your mushrooms. You can easily find hardwood sawdust in any area. Wood chips can also be added in the sawdust mixture for faster colonization. Hardwood species like maple, beech, hickory, and maple are commonly used in this substrate. Others like pine and fir are not recommended as they are categorized as softwood and may not be as effective as hardwood when it comes to providing a good environment for the mushrooms to grow.

  1. Soy Hulls

Soy hulls are another form of a substrate that can be used for mushroom cultivation. It is commonly mixed with wood chips and other materials to form a substrate that provides even nutrients and moisture for your magic mushrooms.

  1. Brown Rice

While this may not be a common ingredient for a substrate, brown rice is also used by some to create a substrate. The brown rice is grounded into a fine powder before it is mixed with vermiculite. This mixture retains moisture and provides enough nutrients for the mushrooms to mature and grow.

Pasteurization and Sterilization of Substrates

Substrates are commonly moist and are filled with materials that easily attract different kinds of bacteria. Bacteria thrive in the same environment as the mushrooms and they can become competition for the nutrients found in the substrate. This is why all substrates need to undergo either pasteurization or sterilization processes. These processes help eliminate contaminants that will reduce the growth of your mushrooms.

Pasteurization is the process of destroying the harmful organisms found in your substrate. The substrate is exposed to the heat of about 150 to 180 degrees Fahrenheit for about 2 hours. While this does not eliminate all the bacteria found on your substrate, it effectively reduces the number thus decreasing the chances of bacterial growth in your substrate. Straw substrates commonly undergo pasteurization.

The sterilization process is much more complex as it involves proper techniques to prevent any form of contamination from start to finish. Sterilization happens when you heat the substrate in high temperatures of up to 250 degrees Fahrenheit at around 15 PSI of pressure. This will eliminate all the contaminants in your substrate.

However, this process will have to remain free of contamination hence you will also need to perform the cultivation process under sterile conditions. This might be too tedious for home growers as you will need different protective equipment when handling the sterilized area to prevent cross-contamination. Most of the time, substrates made of hardwood sawdust undergo sterilization due to its affinity for molds and bacteria.


Whether you would go for pasteurization or sterilization process to reduce the contaminants on your substrate, it all boils down to choosing which is the best substrate for the mushroom spawn. The common denominators include convenience, budget, and the ability to provide good amounts of moisture and nutrients to your mushroom spawn.

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