Open. Mist. Grow. Harvest.
Your grow kit is alive. For best results, activate it as soon as you receive it.
THE GRIB contains a wood-based substrate block fully colonised by living mushroom mycelium. There is no need to prepare substrate, transplant mycelium or use specialist equipment. Open the box, cut the bag, maintain humidity and watch your mushrooms grow.
Quick start
- Open the front panel along the perforated line.
- Cut an X in the plastic bag.
- Mist the opening 2–3 times a day.
- Harvest the entire mushroom cluster when ready.
Jump to a section: Your kit is alive · Inspect before opening · Before you begin · Activating your kit · Daily care · Growth and harvest · Safety & allergy information · Getting another harvest · Troubleshooting · After the final harvest · Need help?
1. Your kit is alive
Mushroom mycelium is a living organism. Its natural purpose is to grow, explore the substrate and eventually produce mushrooms.
For the most reliable result, activate your kit promptly after delivery.
If you cannot start immediately
Do not open or cut the inner bag. Follow the storage instructions printed on the species label.
Storage requirements vary by mushroom species and strain:
- some kits may be kept in a cool place;
- some species may tolerate refrigeration;
- warm-loving strains may need to remain at room temperature;
- certain kits must not be refrigerated.
The species label always takes priority over these general instructions.
Keep an unopened kit:
- away from direct sunlight;
- away from radiators and other heat sources;
- in a clean, dry place;
- in the temperature range stated on the label.
Every kit ships with a printed species label showing the exact species, strain, fruiting temperature, storage-before-activation window, activate-by date and batch number for your kit. Always follow the label inside your box — it takes priority over the general guidance on this page.
2. Inspect the kit before opening
Remove the kit from its shipping packaging and check that the box and inner bag are intact.
Inside the bag you will see a substrate block colonised by mushroom mycelium.
Normal mycelium may look like:
- white or cream-coloured growth;
- a dense white layer on oyster mushroom blocks;
- a very thin, wispy layer on Lion’s Mane;
- slightly uneven colonisation;
- small amber or light-brown droplets;
- a subtle pinkish tone in some Pink Oyster strains.
The white, fuzzy material is usually mycelium, not mould. Mycelium is the vegetative part of the fungus from which mushrooms grow.
Contact THE GRIB support before activation if you see:
- expanding green or black patches;
- excessive slime;
- a torn or punctured bag;
- a strong sour, rotten or chemical smell;
- a large amount of standing liquid;
- severe damage to the block.
If the block was damaged during transport
If the block has cracked but the bag is still sealed:
- Gently press the pieces together through the closed bag.
- Keep the bag sealed.
- Allow the kit a few days to recover under the storage conditions stated on the species label.
- Activate it normally.
If mushrooms are growing near the filter
This means that the mycelium is ready to fruit. Carefully remove only the accessible mushrooms and activate the kit. Do not scrape mycelium from the filter. Do not wet, puncture or damage the filter.
The filter allows the living mycelium to breathe while the bag remains closed.
3. Before you begin
You will need:
- your THE GRIB grow kit;
- the included spray bottle;
- clean drinking water at room temperature;
- clean sharp scissors or a knife;
- a small tray or washable surface under the box.
Wash your hands and clean the cutting tool before use.
Do not remove the substrate block from its plastic bag. The bag protects the block and helps retain moisture.
Activating your kit
Step 1. Open the box
Remove the front panel along the perforated line. Leave the plastic bag and substrate block inside the box. Do not tear the box beyond the marked opening.
Step 2. Cut an X in the bag
Through the opening in the box, carefully cut an X in the plastic film along the marked area.
Important
- Cut the plastic only.
- Do not cut deeply into the substrate block.
- A light surface scratch will not normally harm the kit.
- Do not remove the cut plastic.
- Do not fold the plastic flaps outwards.
- Do not make extra holes.
- Do not cut or puncture the filter.
The X-shaped opening allows air and humidity to reach the mycelium. This provides a signal that conditions are suitable for mushroom formation.
Leaving the plastic flaps in place helps prevent the exposed surface from drying out.
About dense surface mycelium
Some oyster mushroom strains may develop a dense white surface layer. This is often normal and does not need to be removed. Do not make a deeper cut unless THE GRIB support has reviewed a photograph of your kit and specifically recommended it.
Step 3. Mist the opening
Fill the supplied spray bottle with clean drinking water. Mist the X-shaped opening approximately 5–10 times with a fine spray, 2–3 times per day. Adjust the amount according to how quickly the surface dries.
Correct moisture level:
- the plastic near the opening looks moist;
- small droplets may remain on the film;
- the exposed surface does not look dry;
- water does not run down into the box;
- no puddle forms inside the bag or box.
The goal is to maintain a humid microclimate, not to water or soak the block.
After small mushrooms appear
Continue misting gently. Spray mainly around the growing area rather than forcing a strong stream of water into the mushroom cluster.
Step 4. Choose the right location
Place your grow kit:
- at the fruiting temperature stated on the species label;
- in soft, indirect daylight;
- in a room with normal fresh-air exchange;
- on a stable, washable surface or tray;
- somewhere you can inspect it morning and evening.
Do not place the kit:
- in direct sunlight;
- on or beside a radiator;
- beside a cooker or other heat source;
- under a strong air-conditioning stream;
- inside a closed cupboard;
- in a sealed plastic bag;
- in a constant strong draught.
Mushrooms do not use light for energy in the same way that plants do, but soft daylight helps them develop their natural shape and colour. They also need fresh air — a sealed or poorly ventilated space may produce long stems and small caps.
Daily care
Check your kit morning and evening. Focus on three factors:
1. Humidity
The area around the X-cut should remain moist but not saturated.
If it dries completely between mistings:
- mist slightly more often;
- move the kit away from heating or air conditioning;
- use a ventilated humidity tent.
If water collects at the bottom:
- stop misting temporarily;
- allow excess moisture to evaporate;
- carefully drain accessible standing water;
- resume with fewer sprays.
2. Fresh air
Oyster mushrooms need a regular supply of fresh air. Signs of insufficient airflow include:
- unusually long stems;
- very small caps;
- mushrooms stretching upwards;
- distorted or trumpet-like growth.
Move the kit to a more open location. Do not point a fan directly at it.
3. Indirect light
Colourful oyster mushrooms may appear pale when kept in a dark room. Move the kit to a location with soft daylight, but never expose it to direct sunlight.
Using a humidity tent
A humidity tent can help in very dry homes.
- Use a clean, loose, transparent bag.
- Cut many holes approximately 10–15 mm wide throughout the bag.
- Drape it loosely over the kit.
- Do not seal or tie the bottom.
- Mist the inside of the tent as needed.
- Once small mushrooms appear, remove or raise the tent to provide more fresh air.
The bag must not touch or compress the growing mushrooms. A humidity tent should increase humidity without creating an airtight chamber.
Growth and harvest
When will mushrooms appear?
Small mushrooms may appear within several days, but some kits may take approximately one to two weeks. Timing depends on:
- species and strain;
- room temperature;
- humidity;
- fresh-air exchange;
- the condition of the block after transport.
Once small mushrooms appear, growth can be very fast. Check the kit at least twice a day.
Species-specific notes
- Young Golden Oyster clusters may initially look pale or cream before turning yellow.
- Lion’s Mane mycelium is very fine and may look less dense than oyster mushroom mycelium.
- Small amber droplets on mycelium are often normal.
- White fuzzy growth around the base of developing mushrooms is usually mycelium.
When to harvest oyster mushrooms
Harvest the entire cluster when:
- the caps have opened;
- the cap edges are still slightly curved downwards;
- the caps have not become completely flat;
- the edges have not started turning upwards.
Do not wait for the mushrooms to reach their maximum possible size. Harvesting slightly earlier usually provides better texture, better appearance, longer storage life and fewer airborne spores.
When to harvest Lion’s Mane
Harvest when:
- the mushroom has formed a dense white mass;
- visible soft teeth or spines have developed;
- the mushroom is still white or cream;
- there is no significant yellowing or softening.
Do not wait until the mushroom becomes strongly yellow or brown.
How to harvest
- Wash your hands.
- Use a clean, sharp knife or scissors.
- Hold the cluster close to its base.
- Cut the entire cluster as close to the block as possible.
- Remove all small, dried or undeveloped mushroom remains.
- Trim any substrate from the mushrooms before cooking.
Do not remove individual mushrooms from the centre of the cluster. This can damage the remaining mushrooms and leave decaying material on the block.
Safety and allergy information
This product contains a living culture of an edible mushroom species. People who are sensitive to fungi may experience an allergic reaction.
Mature mushrooms naturally release spores. Spores may appear as pale dust beneath the caps or around the grow kit.
To reduce exposure:
- harvest mushrooms before they become overmature;
- keep the kit in a normally ventilated area;
- avoid placing a mature kit in a bedroom;
- sensitive individuals should avoid close or prolonged exposure to spores.
Additional safety guidance:
- children should use cutting tools only under adult supervision;
- do not eat the substrate or mycelium block;
- keep the block away from pets and small children;
- cook all harvested mushrooms thoroughly before eating;
- when trying a species for the first time, begin with a small portion;
- do not consume mushrooms from a kit with mould, slime or an unpleasant smell;
- do not consume mushrooms if you have a known mushroom allergy.
Getting another harvest
After the first harvest
- Remove the entire mushroom cluster.
- Remove all small remaining fruit bodies.
- Leave the block inside the original bag.
- Do not cut a second X.
- Continue lightly misting the original opening.
- Prevent water from collecting inside the bag or box.
A new harvest may begin after approximately one to three weeks. Later harvests may be smaller than the first, although individual mushrooms can sometimes grow larger.
New mushrooms may form at the original opening, around the edge of the previous harvest site, or occasionally near another area of the bag. Check the entire bag regularly.
If another harvest does not appear
Check:
- whether the temperature is suitable for the species;
- whether the opening has dried out;
- whether the kit receives enough fresh air;
- whether water is collecting in the bag;
- whether there are signs of contamination.
If the block has become noticeably lighter and very dry, it may require rehydration.
Rehydration
Do not use one universal soaking time for every species — follow the species-specific guidance on the label included with your kit.
General procedure:
- Keep the block inside its plastic bag.
- Remove it from the cardboard box.
- Place the cut side in clean, cool water.
- Soak only for the time specified for that species and strain.
- Let the block drain fully.
- Make sure there is no standing water inside the bag.
- Return the block to the box with the original opening facing out.
- Resume light misting.
Lion’s Mane blocks require particularly careful handling and may need a much shorter rehydration period than oyster mushroom blocks.
Troubleshooting
The opening dries very quickly
Likely cause: low room humidity, heating or air conditioning.
What to do: mist slightly more often and use a ventilated humidity tent.
Water collects at the bottom
Likely cause: too much spraying.
What to do: stop misting temporarily, drain accessible water and resume with fewer sprays.
Oyster mushrooms have long stems and small caps
Likely cause: insufficient fresh air.
What to do: move the kit to a more open, normally ventilated location.
Colourful mushrooms are very pale
Likely cause: insufficient indirect light or an overmature harvest.
What to do: provide soft daylight and harvest earlier.
Small mushrooms formed and then dried out
Likely cause: a sudden drop in humidity.
What to do: remove dried mushrooms, restore stable humidity and continue care.
No mushrooms appear after 10–14 days
Possible causes: unsuitable temperature, dry surface, insufficient air or recovery after transport.
What to do: check the species label, correct the conditions and send THE GRIB support a photograph.
White fuzzy growth appears on the block
This is often normal mushroom mycelium. Compare it with the reference photographs for your species.
Amber or light-brown droplets appear
These are often natural mycelial metabolites and do not necessarily indicate a problem. Monitor the kit for changes in smell, colour or texture.
An expanding green or black patch appears
This may indicate mould. Isolate the kit, avoid disturbing the affected area and contact THE GRIB support.
The block becomes slimy or smells unpleasant
This may indicate bacterial spoilage. Stop using the kit. Do not consume mushrooms from it. Send photographs to THE GRIB support.
Mushrooms are growing beside the filter
Remove only accessible mushrooms and activate the kit promptly. Do not scrape, wash, cut or puncture the filter.
After the final harvest
When the block no longer produces mushrooms, dispose of it as biological waste or use an appropriate controlled composting method in accordance with local regulations.
Do not release non-native mushroom species into forests, parks or other natural habitats. Do not bury a block outdoors unless the species-specific instructions explicitly allow it.
Need help?
Take clear photographs in daylight and email them to us. Please include:
- mushroom species and strain;
- batch number;
- delivery date;
- activation date;
- room temperature;
- misting frequency;
- a photograph of the entire kit;
- a close-up of the affected area.