Mycelium is the root network of fungi — a living, growing organism that can be cultivated at home from a box on your kitchen counter. Whether you want to grow oyster mushrooms on your used coffee grounds or experiment with certified-organic culture blocks, two European shops on the Grown. partner index ship real mycelium products to your door.
This guide compares them side by side so you can choose what fits your space, budget, and experience level.
## RotterZwam — Grow Kits on Coffee Grounds
RotterZwam is a Rotterdam social enterprise that grows oyster mushrooms on the city's spent coffee grounds — and sells the same grow kit so you can do it at home. Their numbers are published and real: over 419,840 kg of coffee grounds rescued from incineration, 26,693 kg of oyster mushrooms grown from them, and 144,164 kg CO₂-eq avoided. They are B Corp certified.
The **Mushroom grow kit oyster mushrooms (€15.15)** is the flagship: a pre-inoculated block that fruits oyster mushrooms when you mist it and keep it humid. You grow it on your own used coffee grounds — a closed loop from your morning espresso to your dinner plate. A simpler **DIY kit (€8.99)** is also available. Both ship in recycled packaging assembled in Rotterdam by people distanced from the labour market.
RotterZwam ships across the Netherlands and to neighbouring countries. If you are in the Benelux region and want the lowest-cost, most circular entry point to home mushroom cultivation, this is the shop to start with.
[Browse RotterZwam on the partner index →](/partners/rotterzwam)
## La Mycosphère — Certified-Organic Culture Blocks
La Mycosphère is a Belgian mushroom farm producing certified-organic mycelium, culture blocks, and ready-to-grow kits. Their products are certified "BE-BIO-01, Agriculture Belgium" by CERTISYS — verified on each product page. They produce their own mycelium in-house under laboratory conditions on organic substrates of wood sawdust and cereal grains, then ship it across the EU.
The main difference from a grow kit: culture blocks are larger, higher-yield blocks of fully colonised substrate. They produce multiple flushes of mushrooms over several weeks, rather than a single harvest. The **Oyster Mushroom Kit Ready to Grow (€22.50 on EU locale)** is the simplest entry point — a pre-colonised culture block that fruits within two weeks. For more advanced growers, the **Organic Lion's Mane Culture Block** and **Organic Grey Oyster Mushroom Culture Block** offer specialised species with higher yields.
La Mycosphère ships EU-wide via BPost, Mondial Relay, Post NL, DHL, and DPD — covering Belgium, France, Netherlands, Germany, and beyond. If certified organic credentials matter to you, La Mycosphère is the strongest option on our index.
[Browse La Mycosphère on the partner index →](/partners/la-mycosphère)
## Grow Kit vs Culture Block: How to Choose
Both products deliver living mycelium to your door. The difference is in scale, yield, and setup.
- **A grow kit (RotterZwam, €8.99–€15.15)** is a small, pre-filled block that fruits once or twice. You mist it, keep it humid, and harvest in 10–14 days. No extra supplies needed beyond your used coffee grounds. Best for: first-time growers, small kitchens, and anyone who wants to try mushroom cultivation with minimal commitment.
- **A culture block (La Mycosphère, ~€22.50)** is a larger, laboratory-produced block that fruits multiple times over several weeks, with higher total yield. Best for: growers with some experience, households that cook with mushrooms regularly, and anyone who wants certified-organic substrate and specialised species like lion's mane.
The right choice depends on what you want: a quick, low-cost experiment (RotterZwam) or a larger, multi-harvest investment with organic certification (La Mycosphère). Both are regenerative — they turn agricultural waste into food, and the spent blocks compost when you are done.
## What About Other Mycelium Products?
Beyond grow kits and culture blocks, mycelium is used to make packaging, planters, coasters, and building materials — grown, not manufactured. European producers of mycelium-object products exist, and we are researching them for the partner index. If you know of a European mycelium-materials maker we should vet, reach out to our concierge and we will add it to the pipeline.
For now, RotterZwam and La Mycosphère are the two verified mycelium shops on our index. Both sell living mycelium that you can grow at home — the most direct, accessible way to experience what this material can do.
Curious about the science? Read our deep dive: [What Is Mycelium and Why Does It Matter?](/blog/what-is-mycelium-and-why-does-it-matter)
Browse all 69+ vetted regenerative shops on the [Grown. partner index](/partners) — mushroom kits, fermentation cultures, composting supplies, organic seeds, and more, across Europe.