1. Introduction
The substrate is the true foundation of a successful mushroom cultivation. It is what nourishes, hydrates, and supports the mycelium until fruiting. A poorly chosen or poorly prepared substrate can compromise an entire cultivation, even with the best spores or mycelium.
Among the simplest and most effective solutions, the CVG substrate (Coco - Vermiculite - Gypsum) has established itself as a reference choice for both beginner and experienced growers. Easy to prepare, economical, and highly efficient, it is perfectly suited for home cultivation of many mushroom species: oyster mushrooms, psilocybes, medicinal mushrooms, and many others.
In this article, I offer you a complete and practical guide: you will gain a deep understanding of what the CVG substrate is, why it works so well, and above all, how to easily make it with the right materials. Ready to give your mycelium the best chances of success? Let's go!
2. What is the CVG substrate?
The CVG substrate is one of the most commonly used mixes for indoor mushroom cultivation. Its name comes from the three main ingredients that compose it: Coco Coir (coconut fiber), Vermiculite, and Gypsum. Together, these materials create an ideal environment for the mycelium to quickly colonize and produce beautiful fruits.
Coconut fiber: an ideal base for mycelium
Coco Coir, or coconut fiber, comes from the husk of coconuts. It effectively retains moisture while remaining light and airy, two essential elements for mycelium development. Using a coco fiber substrate provides a stable structure, resistant to compaction, and naturally resistant to contaminants.
Vermiculite: for better water and air retention
Vermiculite is an expanded mineral that plays a key role in the balance of the substrate. It improves water retention without making the mixture soggy, and also promotes good air circulation. A coco vermiculite substrate thus ensures an environment that is both moist and well-oxygenated, perfect conditions to stimulate mycelium growth.
Gypsum: to enrich and stabilize the substrate
Gypsum (calcium sulfate) is often added in small amounts to stabilize the pH of the substrate and prevent it from becoming too acidic over time. It also provides calcium and sulfur, two nutrients that strengthen the health of the mycelium. In a substrate for mycelium, gypsum contributes discreetly but effectively to more abundant harvests.
3. Why choose a CVG substrate?
The CVG substrate has established itself as a reliable option for mushroom growers, whether they are beginners or more advanced enthusiasts. Here’s why this simple mix remains a strategic choice for successful cultivation.
An excellent water retention capacity
Thanks to coconut fiber and vermiculite, the CVG substrate maintains an ideal moisture level for mycelium development without becoming waterlogged. This water stability reduces the risk of drying out or excess water, two common causes of failure in home mushroom cultivation.
A low contamination rate
Unlike other substrates richer in organic matter (such as manure or straw), the coco mushroom substrate is low in nutrients for unwanted bacteria. This makes it a cleaner, more stable medium, and easier to secure with simple pasteurization. The CVG is therefore an excellent choice for those who want to avoid contamination.
Great adaptability
The CVG substrate is suitable for a wide variety of mushrooms: psilocybes, oyster mushrooms, reishi, Lion’s Mane, etc. It can be used as is or enriched to meet the specific needs of a species. It is a versatile, reliable, and customizable medium.
A simple and quick preparation
No need for complex equipment or long composting steps: the CVG is easily prepared with accessible ingredients. A good coco fiber block, vermiculite, a bit of gypsum, hot water... and you get a quality substrate, ready to be colonized.
Quality ingredients = quality cultivation
The success of a CVG substrate also depends on the quality of the materials used. A clean, well-loosened coconut fiber free of contaminants is essential. It is with this in mind that the Mycosphere Coconut Fiber Block was designed: a reliable, practical product perfectly suited for fungal cultivation.
4. Product focus: Mycosphere coconut fiber 🌱
To obtain a quality CVG substrate, the choice of ingredients is crucial, and it all starts with good coconut fiber. That is why Mycosphere coconut fiber is particularly suited for demanding growers.
Our coconut fiber block is 100% natural, without chemical treatment or additives. This ensures a clean, healthy, and mycelium-friendly support, with no risk of unwanted residues.
Easy to handle, the compressed block is compact, lightweight, and easy to store, even in a small space. Simply hydrate it to obtain an airy, fluffy, and perfectly textured coconut fiber: ideal for preparing a balanced coco vermiculite substrate.
Whether you are a beginner or a passionate grower, the Mycosphere Coconut Fiber Block provides you with a reliable base to start your crops under the best conditions.
The ideal coconut fiber block for your CVG substrate!
Our 100% natural coconut fiber is perfect for preparing a high-performance substrate. Untreated, convenient to store thanks to its compressed format, it offers an optimal texture after hydration.
Discover the product5. How to prepare your CVG substrate? (Step-by-step guide)
Preparing your own CVG substrate is simple and rewarding. Here is a clear tutorial to succeed every time.
Necessary equipment
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1 block of compressed coconut fiber (like the Mycosphere Block)
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2 liters of medium or fine vermiculite
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50 g of gypsum (optional but recommended)
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Hot water (not boiling)
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A large clean container
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A spoon or a shovel for mixing
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Clean gloves (optional)
Preparation steps
1. Hydrate the coconut fiber block
Placez les ingrédients dans un seau, versez l’eau bouillante, fermez hermétiquement et laissez reposer. Vous pouvez également recouvrir le seau d'une couverture pour prolonger la durée de pasteurisation. Portez toujours des gants de protection pour éviter les brûlures lors de cette opération.
Work in a clean place. After 6 to 8 hours of cooling, mix vigorously to homogenize.
Little tip: crumble the coconut fiber well with your hands to avoid the formation of "compact pieces" that would hinder colonization.
2. Add the vermiculite and gypsum
When the coconut fiber is well moistened and aerated, add the vermiculite and gypsum.
Tip: lightly sift the vermiculite if it contains large pieces to obtain a more homogeneous texture.
3. Mix carefully
Mix everything by hand (with clean gloves) or using a shovel.
The goal is for the vermiculite and gypsum to be distributed uniformly throughout the coconut fiber.
Quick reminder: a homogeneous mixture ensures better colonization of the substrate by the mycelium.
4. Adjust the humidity ("tightness test")
Take a handful of the mixture and squeeze it tightly in your hand:
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If a few drops of water bead between your fingers, that's perfect.
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If water flows freely, it is too wet: add some dry coconut fiber or vermiculite.
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If nothing comes out and the mixture is crumbly, add a little water.
Tip: use a spray bottle or a rain-like water jet to finely adjust the humidity without soaking the substrate.
Substrate composed of a mixture of hydrated coconut fiber, grain spawn, and gypsum, just before being sterilized in the pressure cooker. The addition of grain spawn increases the richness of the substrate, and thus its potential productivity, but it also increases the risk of contamination because bacteria also love the sugars present in the grain spawn.
6. Pro tips for an even better CVG substrate
Even though the CVG substrate is simple to prepare, a few tips from experienced growers can really make a difference. Here's how to maximize your chances of success.
Always check the moisture with the "squeeze test"
The moisture of the substrate is one of the most critical factors. After mixing your CVG, always perform the "squeeze test":
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Grip a handful of substrate in your hand.
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A few drops should bead without running.
If it is too humid, the mycelium can suffocate or give way to contaminants.
If it is too dry, the mycelium will have difficulty colonizing the substrate.
👉 Take your time to adjust the humidity. This small effort at the start can change everything!
Do not pack the substrate too tightly
When bagging or binning, it is important not to compact the CVG substrate too much.
The mycelium needs oxygen to breathe and grow. If the substrate is too dense, it slows colonization and increases the risk of rot.
Tip: gently tap the substrate so that it conforms to the shape of the container without ever forcing or crushing it.
Should gypsum always be used?
Gypsum is very useful, but not mandatory in all situations:
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Use it if you want to stabilize the pH on long cultures (Reishi, Lion’s Mane, etc.) or enrich your substrate with calcium.
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You can omit it for fast-growing cultures like some oyster mushrooms or psilocybes.
👉 In case of doubt, adding a bit of gypsum is often a risk-free "plus."
Adapt the CVG according to the cultivated species
Each species of mushroom has its little preferences:
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Oyster mushrooms: prefer a substrate that is a bit more aerated and lighter (add a little more vermiculite to lighten the texture).
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Psilocybes: love the classic structure of the standard CVG.
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Medicinal mushrooms (Reishi, Lion’s Mane): prefer a slightly more humid substrate and sometimes enriched with additional nutrients.
Tip: by finely adjusting the texture and moisture to the cultivated species, you can achieve faster and more abundant harvests.
Can we enrich its CVG substrate?
Although the standard CVG substrate is already very effective, it is possible to enrich it to obtain more abundant harvests, especially with certain demanding species.
Enrich with sterilized grain spawn
The addition of grain spawn (such as rye, wheat, or millet) in the CVG substrate provides additional nutrients, rich in sugars and nitrogen. This stimulates the colonization speed and can improve production.
Attention: an enriched substrate is also more attractive to contaminants (bacteria, molds). It is therefore essential to handle the grain spawn in ultra-clean conditions and to ensure perfect sterilization.
Enrich with pelletized manure
Composted and pasteurized pelleted manure (horse, poultry, etc.) can be incorporated in small amounts to enrich the substrate. It improves nutrition without making the texture too heavy, provided it does not exceed 10 to 20% of the total volume.
Tip: prefer pasteurized pellets of horticultural quality to limit risks.
A tip for beginners
If you are a beginner, it is recommended not to enrich your CVG substrate. A simple substrate is more stable, less risky, and much more forgiving in case of mistakes.
You may harvest a little less, but you will maximize your chances of success and satisfaction by avoiding losing everything due to contamination.
7. FAQ rapide
Should I pasteurize my CVG?
Yes, it is highly recommended to pasteurize your CVG substrate, especially if you are working in a non-sterile environment. This reduces the risk of contamination and gives the mycelium a head start.
What is the best coconut fiber for making CVG?
A 100% natural coconut fiber, untreated chemically and well loosened, is ideal. The Mycosphere Coconut Fiber Block is specially designed for this use.
Can vermiculite be replaced by something else?
Vermiculite is difficult to replace because it combines water retention and aeration. Failing that, you could try perlite, but the result is often less optimal for fungal cultivation.
Is gypsum really necessary?
Gypsum is not mandatory, but it stabilizes the pH and provides nutrients useful to the mycelium. It is particularly recommended for long cultures or enriched substrates.
How long can I keep my prepared CVG?
The CVG substrate can be stored for 1 to 2 weeks in a clean airtight bag, in a cool place. It is important to check that it does not dry out or develop suspicious odors before use.
8. Conclusion
The CVG substrate is a simple, reliable, and effective solution for successfully growing mushrooms at home. Thanks to its water retention capacity, low risk of contamination, and great adaptability, it stands out as a valuable ally for both beginner and experienced cultivators.
The ideal coconut fiber block for your CVG substrate!
Our 100% natural coconut fiber is perfect for preparing a high-performance substrate. Untreated, convenient to store thanks to its compressed format, it offers an optimal texture after hydration.
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