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Mushrooms are very easy and profitable to grow, but things can wrong if you don’t get your ducks in the row. One of those ducks are substrates – bases for growing mushrooms. They are as important as the soil is for growing any other crop.

However, substrates are much more forgiving than soil since their composition is easier to control and can be reproduced anywhere, anytime. They are also a lot more forgiving when it comes to experimentation. And let’s not even talk about space limitations.

Having a good substrate is crucial – you can have the state of the art growing chambers and other equipment, but if the foundation is shaky, the whole house will fall. Luckily, this is not brain surgery and it’s relatively easy to figure out what type of substrate you need and how you should take care of it.

What do mushrooms like to eat?

Fungi in general have three different types of diet they gravitate to.

A lot of people believe that all mushrooms are parasites, but as it happens, it’s only a portion of species that can be called that. They feed by latching on a living host and draining it of nutrients. This usually ends in the host’s death. This is what honey and lobster mushrooms do, as well as the infamous cordyceps.

Saprophytic fungi feed on the dead matter. This means anything from anything that is just about to start their new career in pushing up daisies, up to ye good olde compost. Here we are talking about the majority of fungi that are “mass-produced” for human consumption – shiitake, oyster, portabella, button mushrooms, etc.

And mycorrhizal fungi are a combination of both. They both the dead and decaying matter, as well as get nutrients from the plants they are rooming with. They often form a symbiotic relationship with those plants and help them gain nutrients or abilities that they don’t usually have (ie better response to stimuli). This group is represented by truffles and the magic mushroom itself, fly agaric.

The last group is the most difficult to cultivate on a substrate (with truffles being particularly uncooperative). However, we can easily reproduce a perfect growing environment for the first two.

What are the best kinds of substrates?


Straw is a top choice of substrate material for most growers since it provides amazing yields and is suitable for numerous types of mushrooms. It’s also very cheap. Straw from any cereal can be used, and you can even experiment to see which one will suit your crop the best.

But, two things. One, this stuff can get seriously messy so it’s not suitable for a small apartment or garage-based operation. And two, you must sterilize it properly since it’s very easy for some microorganisms and other fungi to sneak in and compete with your crop for nutrition.


Sawdust is a must-have for any species that typically grown on trees and tree roots. It will provide all the nutrients that the mushroom was getting from it, but at the same time, it can be mixed with other things for maximum performance. Bran is one of the items that often end up in such mixtures, but anything is possible as long as the mushroom likes it.

Growers usually use oak, beech, and maple, which makes them ideal for growing oysters.


Bring in the logs when the sawdust is not good enough.

This kind of substrate is best if you have access to some woods and want to grow your crop in a more natural environment. There’s no need for special chambers and humidifiers, plus the logs are reusable without too much additional prep.

But don’t expect the same yield as you would get indoors. And you will have to deal with seasons.

Soy hulls

Soy hulls are the byproduct of soybean oil production. They are extremely rich in nutrients and are suitable for growing most species of edible mushrooms. In fact, soy hulls are one of the favorites of large commercial growers since they are not as messy and suitable for factory settings.

The hulls are cheap to buy, and you can even get them for free from a local oil producer if you have one. The only issue is that it doesn’t provide as great of a yield as straw does.


Coco coir and vermiculite

Coco coir is a mixture of ground coconut hulls and shells. Vermiculite is a silicate material that is often used in planting. They are quite often used together, but you can fud them separately in different bulk substrate recipes.

Just don’t mix up coco coir with coco fiber – they are quite similar, but the latter is completely useless to you.


It’s usually used as a part of a recipe for a substrate instead of on its own. It’s usually sterilized twice before use.

The button mushrooms you’ve picked up at the supermarket last week were probably grown on a manure-based substrate.

Compost and other waste product

They are decaying, so saprophytic fungi will come over for lunch.

Compost is usually used either on its own, or it can be mixed with manure and other materials to make a bulk substrate.

How to make the best mushroom substrates

The best substrate is the one that matches the spawn and mushroom you’re growing. Though you can make a safe bet by matching the substrate to the host said shroom latches on in nature (ie wood shavings for ones that grow on logs). Always start by doing in-depth research on your species of choice.

Of course, you can start the other way round as well and choose a substrate before you pick a species (or several) of mushrooms that go well with it.


How to pasteurize and sterilize your substrates

Pasteurization is pretty simple – all you have to do is to keep the substrate temperature in the range between 160 and 170 degrees Fahrenheit for one hour. The easiest way to do this is by boiling it in a plastic bag. And if you want to make your life easier, you can get a sous-vide circulator that will do all the work for you.

Make sure to cool down the substrate completely before you inoculate it.

Sterilization can happen in several different ways. The cheapest and easiest is scalding, aka submerging the substrate in hot water. Another easy method is by using chemicals, but that one can get pricey very quickly.

You can also soak the substrate in a lime solution for one day, or mix in with compost for one week.

People on the internet seem to like the pressure cooker method the most. It makes sense since it’s fairly easy, quick, and foolproof. Once the cooker reaches 15 psi, you just have to leave it all there for 45 minutes. And there’s no need for a fancy setup – a decent quality model that’s designed for home use will do.

The most labor-intensive one is the process called tyndallization. It consists of several cycles where the substrate is treated at different temperatures for 72 hours. You start by bringing the material to 212 degrees Fahrenheit for 30 minutes, then keep it at 99 degrees for 12 hours. Repeat the cycle over and over, and finish with a final 30 minutes at 212 degrees.

What substrates produce the highest yields of mushrooms?

Straw based substrate comes at number one here. It’s followed up by sawdust, soy hulls, and manure.

But that’s just the starting point. Different species of mushrooms require a different cocktail of nutrients and each will have a base that works better for them. Also, there are the things you do and the environment you’re growing the mushrooms in.

Straw is a decent place to start, but you should never stop experimenting and trying to see what works best for you.

What’s a bulk substrate and how it’s made?

Bulk substrates are mixtures of several nutritious materials that are used to grow mushrooms. The most important way they differ from the regular kind is that they can’t be inoculated with liquid culture or spore solution. You need to create something called grain spawn (usually millet or rye grain that is inoculated with mushroom spores), and then that’s mixed into the bulk substrate.

The bulk substrates themselves consist of multiple ingredients, with at least one of them being animal manure. Regular plant compost can also be used, but it’s not a great replacement for manure in this case.

Multiple recipes are floating about cyberspace, and which one is ideal depends solely on the species of mushrooms you’re growing. Most of them have only 2 or 3 ingredients, but there ones where the list goes into the double digits. Pretty much, it’s safe to assume that the ones with more ingredients will also be more nutritious.

Bulk substrates must also be pasteurized before adding the grain spawn. Sterilization is a no-go since it can kill some of the goodies from the compost and manure.

When growing with bulk substrates, growing chambers are a must. Some monitoring equipment will not hurt either, since you will have to keep an eye on what else (if anything) is growing in there with your shrooms.

All species of mushrooms like this method of growing, no matter if they are edible or medicinal. The trick is only in finding the recipe that suits your chosen species the most.


What are the best mushroom fruiting conditions?

The ideal temperature for fruiting is between 70 and 79 degrees Fahrenheit. And, as it’s the case with mushrooms at any time, the area should also be dark and damp.

The ideal humidity level is about 9-% Mycelium is perfectly able to maintain humidity on its own when it grows, but it will need a lot of help in those early weeks. You can easily do this with the help of humidifiers, or by misting the crops regularly.

Fresh airflow is also very important. You will need to provide as much of it as they would have if they were growing in the wild.

But before you start with setting up any of that stuff, you will have to ensure that everything is clean and sanitized. Washing the area with soap and water will do the trick, but you can also follow it up with a disinfectant to be on the safe side.

There must be no mold before you start growing since it’s easy for it to take over everything.

What temperature does mycelium grow best in?

Shrooms like to be somewhere between 75 and 80 degrees Fahrenheit. The slight deviation may slow their growth and lessen the yield, but extreme fluctuations will kill the whole crop.

What do I do so I don’t kill my mycelium?

The most significant thing is to maintain the ideal temperature. Most importantly, never crank up the heat. Cold may send it to sleep, but the heat will kill both the mushroom and its spores.

Other than that, try to avoid acidic environments and solutions. Vinegar is a common ingredient in many home fungicide recipes because mushrooms are not very keen on the acid. In fact, when exposed to it, they will dry out and die. So, keep an eye on the pH of the substrate and the water in the humidifiers.

How long can you expect your mycelium to live?

At the normal room temperature, you can expect about 6 to 8 weeks of life without spoilage. This is, of course, after they have fully grown (with the average growing period of a lot of edible mushrooms being about 3 weeks).

If you want to preserve your mushrooms for longer, you will have to move them to the fridge. You’ll get at the very least about 3 more months out of them, though you can double that with additional effort and attention to temperature consistency and other environmental parameters.

Proper storage can get you even years of life, with some growers and labs reporting that they still have specimens that have been around for decades.


How long can a mushroom substrate last?

Once you’ve pasteurized your substrate, you have at least a couple of days (if not up to 2 weeks) to proceed with your next step. Though keep in mind that most growers prefer to use it as soon as possible. They also report diminished yields if they leave their substrates to linger around too long after pasteurization.

But how long a substrate cake can last once you receive it and while it’s still in the original packaging, depends on the manufacturer. They will provide you with detailed info about the expiry date as well as the best storage solutions. As a ballpark, you are looking at 6 months on average, but still, consult with your supplier before you buy it if you don’t plan to use it straight away.

The dry materials are very shelf-stable, but you will have to make sure they stay dry and that they don’t start developing mold.

How long can a mushroom substrate last once I start using it?

Usually, anything from a couple of weeks to months (and in rare cases, years). This truly depends on how you use it and what species of mushroom you’re growing.

If you are reusing a substrate, pay attention to your yield. Once the numbers go down by about 10%, it’s a decent sign that it’s time to retire it. You could try and squeeze one more crop out of it, but don’t plan on using it for any longer after that.

Proper substrate storage for longevity

When your order comes in, more often than not the original packaging will be enough to keep your substrate in tip-top condition until you’re ready to use. Unless the manufacturer has stated otherwise, you can pretty much move it somewhere cool and dry, and be done with it.

But once you open the package, the only thing that will help in the long run is vacuum packing. Regular airtight containers are a decent first-aid solution, but you will have to break out the big guns if you need to store your substrate for weeks or longer.

A standard vacuum sealer that you can pick up at a local big box store will do the trick for a small family farm (especially if you’re okay with packing it in smaller chunks). Anything bigger than that, you will have to go commercial-grade.

How many times can I reuse a mushroom substrate?

The answer to this question depends on the original type of mushroom you were growing, which species do plan to grow after, and how you’re going about all of it. But in any case, it’s safe to say that you can get at least a couple of extra uses from a substrate.

When it comes to edible mushrooms, you can freely reuse a substrate to grow several crops. Shiitake, for example, grow rather well on a substrate that was previously used for the same type of crop.

Medicinal mushrooms are a little bit more problematic and finicky. As in, you will not get a second generation of the crop with the same substrate. However, you can at the very worst squeeze out one batch of regular edible mushrooms.

Your best bet is to use the spent substrate to inoculate the new one. You pretty much have to crumble and mix them, then leave them to incubate.

Also, if you want to get the most out of all your substrates, remember to “rotate” the crops. Generation after generation, you will get a better yield if you’re not growing the same species on the same substrate (even if the said substrate was already used numerous times before).

mushroom compost-in. pot

What can I do with the mushroom substrate when spent?

First and foremost, you can compost it or use it on its own to fertilize and grow other crops or regular plants. Even when it becomes unsuitable for growing mushrooms, it’s still full of amazing nutrients that can do some fantastic things for your veg.

SMS (spent mushroom substrate) is ideal for freshly seeded lawns. Not only will it feed the soil and help the lawn grow to be rich and lush, but it will also provide physical protection from the birds that may decide to snack on the seeds. Just make sure the substrate is at least 6 months old before you start using it for these two applications – this is to prevent any unwelcome reappearances of the mushrooms you were growing due to leftover spores.

Another use (that doesn’t require a proper lab) is as a source of energy. Even with a small mushroom farm, you can produce enough biogas to serve the needs of your household. If your production is on a lot larger scale, you could even make some money out of it. If you want to learn more about this in detail, this paper covers everything in detail, from pre-treatment and storage to the processing options.

All other applications require more tinkering and some specialized equipment. SMS can be used as food for some animals, but it will need some processing before it’s safe to consume.

Several interesting compounds can be extracted with all that extra tinkering. Some of them can neutralize various ait, water, and soil contaminants, while others can be used to produce a plant hormone that can vastly increase the yield of vegetables and legumes.

How to enjoy the process

At this point. someone could say that your mushroom farm is like a pet. However, the truth is that it’s more like a little Tamagochi egg – a lot easier to grow and take care of. Well, at least when compared to other types of farming.

What’s unique and most satisfying about growing mushrooms is the speed at which everything is happening. You can see the fruits of your labor in weeks, instead of months or even years. And this is what gives you the freedom to play.

Of course, you will have to do what you know works best to secure your profits, but you can also have a small sample with which you can pretend to be a mad scientist. That’s what’s going to bring more color into the sometimes monochrome rut of growing and harvesting.

So, just let yourself go and have fun experimenting. Embrace all mistakes and failures, and celebrate every success. Who knows, maybe you’ll even make a big enough discovery to earn you a mention on the Saturday morning news.