Growing mushrooms is a fun, satisfying hobby for some and a grower’s passion for others. What lies in common for all is the need for the right growing base to help their mushrooms thrive. Without the right base, mushroom spores can’t truly thrive.
Read on to learn all the details about the different mushroom substrate bases, how to choose the right one for growing your mushroom variety of choice, and more!
What is a Mushroom Substrate and Why Is It So Important?
Knowing about mushroom substrates is one of the most important keys to learning how to grow the types of mushrooms you want. Not all mushroom substrates are created equal–and not every type of mushroom will grow in the same sort of substrate.
The best way to think of mushroom substrate is to think of it as similar to soil. Just as you need the proper soil base with the right nutrient balance to grow various types of plants, different varieties of mushrooms also need their own unique substrate in order to flourish and thrive.
The General Rules of Mushroom Substrate
While there are numerous kinds of mushroom substrates to choose from, most of these will have a few properties in common. For example, mushroom substrates are usually full of fibrous, woodlike, and carbon-dense components that allow mycelium to grow. They need to be devoid of any other living organisms that might compete with the mushroom mycelium.
Typically, a substrate substance will need a percentage of nitrogen, along with traces of potassium, sulfur, phosphorus and calcium, and magnesium. There should be a balanced PH level between 5 and 6.5 and a minimal moisture content of 50% to 70%
Common Types of Mushrooms Substrate
Coconut Coir
Coconut coir, or coco coir, is a fancy name for a material derived from ground up coconut hair and husks. Coconut coir is available at many lawn and garden centers and is typically mixed with a yellowish brown mineral called vermiculite.
When combined, these two elements make an ideal mushroom substrate. The general ration is eight cups of vermiculite to every one and a half pounds of coconut coir, all mixed together with about 16 cups of boiling water.
This mushroom substrate will expand quite a bit once it fully absorbs the water, so be sure to mix it in a large container!
What Type of Mushroom to Grow in This Substrate
Because it retains moisture so well and is so resistant to colonization from unwanted bacteria, fungi, and outside spores, coconut coir proves to be a very versatile type of mushroom substrate. Amusingly, it’s often championed for growing hallucinogenic mushrooms.
However, many of your standard edible mushroom types will also thrive when coco coir is mixed with their other base mushroom substrate materials, such as manure, straw, etc.
Coffee Grounds
Coffee grounds are another highly popular base for a mushroom substrate. They are easy to come by, reduce the waste generated by tossing out used coffee grounds, and typically need very little in the way of addendums to make them a perfect substrate.
This is largely due to the fact that the brewing process with coffee grounds serves to pasteurize them. This then eliminates the need for additional sterilization, so once you have your coffee grounds brewed and are ready to discard them, you are good to go!
The fresh coffee grounds and mushroom spores can simply be combined in a blender to begin the inoculation process of the mushroom mycelium. One thing to note is that espresso grounds are the ideal substance to use, since they usually retain a more balanced amount of moisture as opposed to cafe style coffee that often sits in quite a bit of water.
What Type of Mushroom to Grow in This Substrate
Coffee grounds make a great mushroom substrate for several popular varieties of mushrooms. These include oyster mushrooms–such as pink, gray, and yellow or gold oysters–as well as shiitake and reishi mushroom types.
Logs
Often, in and around logs is where you will find wild mushrooms growing at will–so it stands to reason that this is a perfect option for a mushroom substrate at-home growers can use, too. An added bonus of log based mushroom substrate is that you can often gather a longer harvest, as the mushrooms will tend to spawn again and again within the log.
As a general standard, you want to aim for cut logs that fall into the hardwood category. This includes beech, maple, oak, etc. These are typically the best types for inoculating with mushroom spores, as they are often liked by even the pickiest mushroom varieties.
You want your mushroom substrate log to be about three feet long and five feet in diameter, and give it several weeks to settle past cutting before you inoculate it.
What Type of Mushroom to Grow in This Substrate
Many well known wild and domestic mushrooms absolutely thrive in a log based mushroom substrate. Some of these include turkey tail, wood ear, shiitake, reishi, oyster mushrooms (such as yellow or gold, pink, and gray oysters), maitake, and lion’s mane.
Manure
Because mushroom substrates require sterilization of some sort before they can play proper host to mushroom mycelium, manure is not typically considered the ideal mushroom substrate. This is a substance already teeming with all sorts of microbial life and organisms, which are hard to sterilize.
However, there are certain mushroom types that simply grow their best in a manure mushroom substrate. With that being the case, manure can be made into a useful substrate by adding enough water to reach field capacity (meaning the manure is soaked without additional water pooling in it). Then, you can either sterilize it by baking it, or pasteurize it.
Generally, you will also need to mix the manure with another substrate type, such as coco coir, to achieve the perfect mushroom substrate.
What Type of Mushroom to Grow in This Substrate
Button mushrooms are a variety that grows best in a manure based mushroom substrate.
Straw
Straw is a highly popular and effective mushroom substrate for growing several varieties. It’s also well liked because it’s generally affordable, easy to come by, and easy to work with. Most straw is compatible with mushroom growing, although you will want to avoid using any straw treated with eucalyptus, which is a natural fungicide and will prevent your mycelium from colonizing.
Because of its natural base compounds, straw does usually lack the necessary one to two percent nitrogen levels required for an effective mushroom substrate. To achieve this threshold, you can pasteurize the straw in a heat resistant bag placed in boiling water for up to an hour, or ferment it for up to a week in an airtight container.
What Type of Mushroom to Grow in This Substrate
Mushrooms that thrive in a straw based substrate include enokitake, pioppino, shaggy mane, garden giant/wine cap, and various oyster mushrooms. This includes gray oyster, pink oyster, and yellow/gold oysters.
Hardwood Pellets
If you are looking for some of the same benefits in your mushroom substrate as you would get from a hardwood log, but without using the log itself, you have the option of using hardwood pellets. Usually based in maple, beech, and oak, these hardwood pellets are often sold for use in grilling or smoking. You just want to avoid ones with smoke flavor or the common apple or hickory flavoring.
Given their common use, hardwood pellets are relatively easy to come by and make for an easy mushroom substrate. Simply mix 10 cups of hardwood pellets with 2.8 liters of water to create 10 pounds of mushroom substrate. You can also mix in a couple of cups of bran to supplement the nutritional base your mushroom substrate needs in order to fully support the mushroom mycelium.
What Type of Mushroom to Grow in This Substrate
In addition to oyster mushrooms, reishi, shiitake, and other mushroom varieties that thrive in hardwood logs, you can also grow varieties such as chestnut mushrooms, pioppino mushrooms, and more in a hardwood pellet mushroom substrate.
Cardboard
Finally, the underdog champion of mushroom substrate is simply…cardboard! This ingredient for mushroom substrate is rapidly growing in popularity due to its ease of access, recycling of otherwise waste material, and how straightforward it is to use.
Cardboard can be made into a proper mushroom substrate simply by soaking it in boiling water, then letting it cool and ringing out the excess water. Then you can colonize it with aggressive mushroom spores, such as oyster mushrooms.
You can also help your cardboard mushroom substrate along a bit by adding in coffee grounds, coconut coir, or other addendums.
What Type of Mushroom to Grow in This Substrate
Oyster mushrooms will typically grow quite well on just the damp cardboard itself. You can even colonize a cardboard mushroom substrate with the stems of oyster mushrooms purchased from a grocery store!
However, with adding in coffee grounds and other addendums, you can grow many types of mushrooms, both aggressive and not so aggressive proliferators, in a cardboard based mushroom substrate.
Frequently Asked Questions About Mushroom Substrate
Where can I purchase mushroom substrate?
In many cases, premade mushroom substrate can be purchased from retailers. Places like Amazon, and many local lawn and garden centers, will offer premixed, already sterilized or pasteurized mushroom substrates containing the proper nitrogen balance and mineral components.
However, something to bear in mind when purchasing premade mushroom substrate is, again, whether or not the substrate mix is a good fit for the type of mushrooms you plan to grow. Not every substrate mix will declare on the label what its base components are, so you may not be purchasing a prepared substrate that will mesh well with your intended mushroom spores.
Always be sure to read labels and do your research when purchasing a prepared mushroom substrate.
Should I make my own mushroom substrate?
If you can get your hands on the necessary base ingredients, creating your own mushroom substrate is often the best way to go. It can take some time to learn the proper methods of sterilization and pasteurization, but once you’ve got the hang of it, this is truly the most foolproof method to ensure you are pairing the right substrate with the right mushroom mycelium.
It’s also worth noting that there are some relatively easy ways to make your own mushroom substrate, such as when using cardboard or coffee grounds. You can take your time learning and familiarizing yourself with the process before moving on to more complex mushroom substrate types, such as logs.
What is the pasteurization and sterilization of mushroom substrate and why is it important?
Pasteurization and sterilization are methods by which mushroom substrate is made into a “clean slate,” free of competitive microbial life and organisms, for mushroom mycelium to thrive in. This is often a necessary process because the damp, nutrient-dense conditions in which mushroom mycelium thrive also play host to a lot of different molds, bacteria, and other microorganisms.
If left unchecked in an unsterilized or unpasteurized environment, these organisms can often grow faster and more aggressively than the mushroom mycelium. This gives your mushroom variety little chance to grow. They can also infect your mushrooms, causing discoloration or decay.
Mushrooms sporting these signs of contamination should not be consumed, as the presence of the bacteria can make you ill.
How is mushroom substrate pasteurized or sterilized?
Pasteurization is done by heating the mushroom substrate to temperatures between 150 and 180 degrees Fahrenheit for an hour and a half to two hours. While pasteurization won’t wipe out all organisms in your mushroom substrate, it will reduce them enough for most mushroom mycelium to take over.
Sterilization, on the other hand, heats the substrate to 250 degrees Fahrenheit with additional pressure, which will kill all microorganisms in the mushroom substrate.
This is the key difference between pasteurization and sterilization: the pasteurization process reduces the presence of organisms, while sterilization aims to eliminate them entirely.
Do I always have to pasteurize or sterilize my mushroom substrate?
Not all mushroom varieties need pasteurized or sterilized mushroom substrate in order to thrive. In fact, some varieties will not grow at all in a cultivated or sterilized environment! In the same regard, some mushroom substrates are naturally more sterile than others, such as coffee grounds or cardboard.
What if I accidentally use the wrong mushroom substrate?
Even if you use the wrong substrate, typically you still have a chance of growing some mushrooms. You may not be able to grow as many or as well, but mushrooms are quite hardy and even in a less than ideal environment, you may be able to reap a small harvest.
You can also start over and try again! Unlike crops that require a specific growing season, growing mushrooms can be a year-round venture. So, if you find yourself using the wrong substrate, it’s never too late to start over with the right one.
Wrapping Up The Essential Guide to Mushroom Substrate
Feeling inspired and confident in your knowledge about mushroom substrates? Now it’s time to start growing! Check out our Mushrooms page to learn about all sorts of varieties!
- About the Author
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Renee Dugan
Renee Dugan is a lifelong writer, professional editor, and lover of all things nature, gardening and the big outdoors.
A Midwest girl who’s been in the garden since she could first hold a hand trowel, Renee’s love of growing things has bloomed into a passion for healthy living, holistic lifestyle, and knowing where our food comes from.
Now a mother and maturing gardener herself, Renee is passionate about channeling everything she knows and continues to learn about gardening into lessons for her son and others. Her excitement for sharing this knowledge is only superseded by her excitement about being able to finally grow her own citrus plants in pots.
Renee can be reached at renee.s.dugan@gmail.com
