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What Is A Mushroom Terrarium And How Does It Work?

If you’ve ever taken a walk in the park or gone on a hike in the forest, you’ve probably seen mushrooms growing around. You might have even seen them grow in your front yard. They seem like great candidates for plants to go in a terrarium. Can it really be done?

Here’s the answer: mushrooms can be grown in a terrarium, however their requirements will be different than most plants. Rather than planting a seed, you will need to inoculate the substrate with mushroom spawn. Their growth will also strongly depend on the growth medium/substrate. Their growth conditions might also be a little bit more strict than some common terrarium plants.

As you can probably guess, mushrooms are pretty different from your typical terrarium plants. These differences are not just visual. They have special growth requirements that you will need to pay attention to if you want the best chances of growing mushrooms in your terrarium successfully.

So let’s get into how you can actually grow mushrooms in your terrarium.

What are mushrooms exactly?

So you probably know what a mushroom looks like or you at least know one when you see one. You might have even had some when you last had Chinese food. But do you actually know what mushrooms are?

Mushrooms aren’t plants, but rather are a type of fungus with over 50,000 different species. As a matter of fact, mushrooms are actually more closely related to animals than to plants. Unlike plants, they breathe oxygen instead of carbon dioxide (just like animals) and produce microscopic fungal spores rather than seeds.

What most people visualize when they think of mushrooms is actually just the fruit. The body of the mushroom is actually the mycelium, a web of tiny filaments called hyphae that are usually hidden in the substrate. The mycelium kind of looks like white fuzzy stuff, much like the stuff that you see on moldy bread.

They also tend to grow pretty fast, seemingly appearing overnight. The reason they can grow so fast is that often the invisible body of the mushroom, the mycelium, has been storing up nutrients while hiding in the soil, but only fruit once a year in certain seasons. The mushroom fruits actually grow through cell enlargement rather than cell division which means that the cells can expand rapidly with very little energy. 

Mushrooms have all sorts of different uses. Everyone knows that mushrooms can be eaten, but that only comprises about 3,000 species or about 6% of mushrooms. It’s also pretty well known that mushrooms can be hallucinogens, but those also are a small fraction of mushrooms, roughly 200 different species or 0.4% of mushrooms.

Mushrooms are saprotrophs, meaning they don’t get their energy from the sun (although their growth will be influenced by the direction of light). Instead they get their energy by digesting organic matter. Essentially, organic matter is transferred through cell walls along the mycelium, white, thread like branches akin to plant roots.

What this means for you is that the substrate you choose for your mushroom will have a big impact on how well your mushroom does. To further complicate things, each mushroom will have its own preference for the substrate it will grow on.

We’ll get to that later.

How do you grow mushrooms in a terrarium?

There are certain growth characteristics of mushrooms that are common to most species. However, as any experienced mushroom grower can tell you, each species will have its own preference for growing conditions.

For beginners

If you’re a complete beginner and don’t want to get into anything too complicated, you can get started with a mushroom kit. All of the research and hard work has been done for you and all you have to do is just take it out of the box and follow the instructions.

Mushroom kits will come with the growing medium already inoculated with mushroom spawn. So all you would have to do is cut a piece out, place it in your terrarium, and watch it grow.

For the best chances of success, I recommend starting with either oyster mushrooms or button mushrooms.

Advanced techniques

If you want to go the DIY route, that’s going to be a little bit more complicated, but will give you more options to choose from. This is the way to go if you want to get serious about growing mushrooms or just want to grow certain mushroom species that you can’t seem to find in a kit.

Here’s a rough overview of how mushrooms are grown/cultivated from spores to fruit:

  1. Get a spore print or spore syringe
  2. Inoculate your spawn with the spores to grow mycelium
  3. Place the colonized spawn in a growth medium
  4. Give it plenty of moisture and wait for the mushrooms to fruit

So if you’re like me when I first looked into this, you’re probably confused and/or overwhelmed right now. Let me explain what’s going on here.

Mushrooms produce spores. That’s how they reproduce. A spore print is essentially where mushrooms have been placed onto a surface where their spores can collect in small piles, leaving a “print” of spores ready for use.

A spore syringe is another way spores are collected and distributed. It’s essentially spores that are added to sterile water. This can be injected into a growth medium for the spores to create mycelium.

Just a quick note, if you’re working with spores to grow your mushrooms, everything needs to be extremely sterile. This means wiping everything down with alcohol, wearing gloves, and working in still air or a laminar flow chamber. If you’re interested in learning more about that, check out this post.

That’s why working with spores is not recommended for beginners, it’s kind of complicated, there’s a lot of equipment needed, and there’s a lot of places to make mistakes. However, that will allow you to grow virtually any mushroom species you can get your hands on. You could even go foraging for your own mushroom species in the wild and propagating them yourself if you wanted to.

What I recommend for people who don’t want to work with spores, but still want a little bit more options available to them is to start with mushroom spawn.

Spawn is pretty much small grains that have been colonized by mycelium. You can add this spawn to a substrate and have it grow on its own. You can think about these as akin to mushroom seeds, although they technically aren’t seeds.

If you have spawn, all you have to do is mix the spawn with a substrate or growth medium and watch your mushrooms grow. Essentially, you’ll be skipping steps one and two and jumping straight to step three. That cuts out a lot of work on your end.

Once your spawn is mixed in with the growth medium, all that’s left to do is give your mushrooms plenty of fresh air and humidity to grow. 

This gets a little bit complicated if you’re trying to grow them in a terrarium. In a closed terrarium, you’re going to get plenty of humidity, but you might have some trouble getting your mushrooms enough fresh air and oxygen to breathe. 

One way you can do this is to open up your terrarium once in a while to let fresh air in. The other option you have is to drill some holes so that air can get in. The downside of that is you’re going to have to water it more frequently to maintain the humidity levels.

If you’re growing your mushrooms in the right temperature with plenty of humidity and air, you should see your mushrooms start growing within a couple of weeks. If you want to harvest your mushrooms, your spawn should be good for several cycles of mushroom fruit.

What conditions are needed for a mushroom to grow?

Mushroom terrariums are a little bit different than a standard terrarium because mushrooms have different needs than most plants. At the same time, growing mushrooms in a terrarium have some advantages over growing mushrooms out in the open.

Some of these needs include:

  • Oxygen to breathe
  • Specific temperature requirements
  • Specific substrate requirements
  • Sterile growth conditions

Let’s walk through these one by one.

Do mushrooms breathe oxygen?

Mushrooms are not plants. One of the big differences that comes out of this distinction is that mushrooms will need to breathe oxygen instead of carbon dioxide (although plants sometimes do need oxygen). 

What this means is mushrooms may not have such a good time growing in a closed container on their own. They will need some ventilation to get the oxygen that they need to breathe. 

However, if you are also growing other plants in your terrarium along with your mushrooms, they should be able to produce some oxygen for your mushrooms to breathe without having to have some ventilation in your terrarium. Your mushroom will also provide your plants with carbon dioxide to breathe, complementing their ability to produce oxygen through photosynthesis.

One thing to note is that different mushrooms will have different oxygen needs and that each terrarium will have a different ratio of plants to mushrooms. This means that you should always watch your terrarium plants to see if any adjustments need to be made.

The other thing you need to watch for is that your mushrooms aren’t being soaked in water. Mushrooms breathe oxygen through cell exchange in contact with the air. If they are completely covered in moisture, that’s going to block them from being able to breathe. Preferably, it’s best to direct the water to the substrate rather than at any mushroom fruit.

what temperature should you grow your mushrooms at?

Mushrooms like dark, cool, and humid environments (just like moss). Unlike plants, they don’t even need sunlight to grow.

Mushroom species will have their own temperature preferences, but for the most part, growing them at a comfortable room temperature around 70F will be sufficient for most species. Just make sure to double check your research before planting your mushrooms.

Depending on your area’s climate and whether or not you have indoor heating or cooling, you might need to buy a heating lamp or perhaps find a cooler to grow your mushrooms in if your area is really hot. If your temperatures are too extreme, you might find it difficult to find success growing mushrooms, although it should still be possible with the right equipment.

If you’re growing your mushrooms from spawn, you might want to keep the temperature a little bit warmer in the beginning, maybe reaching temperatures of about 80F. But once mycelium starts to grow, your mushrooms should start generating a little bit of heat on their own, so you can drop the temperature a bit.

You’re also going to want to keep your mushroom terrarium out of direct sunlight and keep the soil moist. This will avoid letting them dry out or letting the temperature get too hot inside your terrarium. Remember, a terrarium acts like a tiny greenhouse and sunlight can easily heat up a terrarium to high temperatures.

What substrate should you use for growing mushrooms?

The mushroom substrate is the material that your mushroom mycelium is going to colonize. If you’re starting from mushroom spawn, this is the material that you’re going to put the mushroom spawn in to grow your mushrooms.

Mushrooms, like most fungi, get their energy by decomposing organic material. In other words, they digest the substrate. What this means is the substrate will matter a lot more than it does for plants. Some species will even prefer to grow in a solid block of wood!

For the most part, the substrate is going to be some type of woody, fibrous material. They also usually have small amounts of minerals and nitrogen for your mushrooms to use as nutrition.

Some common ones that you might see include: 

  • straw
  • sawdust
  • manure
  • coir
  • cardboard
  • Coffee grounds

The substrate that works best will depend on the particular mushroom species you are trying to grow. But if you’re looking for a substrate that will work fine for a large number of mushroom species, try starting with coffee grounds. One of the benefits of using coffee grounds is that they should already have been sterilized by the brewing process, which means you can start growing mushrooms in it right away without having to sterilize it yourself.

Sterile growth conditions for growing mushrooms

One of the challenges with growing mushrooms is that you’ll want to avoid competitor organisms. Any substrate you’re going to use is going to be a great breeding ground for all sorts of different fungi and bacteria. If you want to make sure that you are only growing the fungi that you want, you’re going to want to minimize the competition by sterilizing the substrate.

Sterilizing the substrate is a bit out of the scope of this article, but basically you would have to either boil or pressure cook your substrate at high temperatures to kill off any unwanted organisms or bacteria. This is an important step because if there are too many competing organisms in your substrate, that could prevent your mycelium from growing or reducing your mushroom yield. You probably don’t have to worry about this step if you are using a mushroom growing kit with an established mycelium colony.

A sterile working area is even more important if you’re starting from mushroom spores. If you’re cultivating mushrooms from spores, your mushrooms are going to have a much harder time fighting and competing with all the other thousands of fungi, bacteria, and other organisms that could be present in your environment compared to a mycelium colony that has fully established itself.

You might see sources that say you’ll need to work with a laminar flow hood on top of constantly spraying and wiping down your work surface with alcohol. But in case you don’t have all that fancy equipment, you can always give it a try with what you have and hope it works out. You may find that your mushrooms will turn out fine anyways, although you might have a smaller chance of that happening.

When thinking about competition and sterilization, you don’t need to worry about any of your terrarium plants competing with your mushrooms. Fungi and plants tend to go hand in hand. There’s no need to spread out your plants from the mushrooms or constrain yourself to a mushroom only terrarium.

Mycelium can wrap around nearby plant roots if your mushrooms can grow in soil. But this is no cause for concern. This can actually be beneficial to your plants by providing essential minerals and water to them. It’s also beneficial for your mushrooms because they can take in sugars created by nearby plants. It’s a symbiotic relationship called a mycorrhiza.

In terms of growth conditions, if you can meet those four criteria, you’ll probably have good chances of successfully growing mushrooms in a terrarium.

Thanks for reading. Check out some of the articles below if you’re interested in reading more.