Grow kit instructions
Blue Oyster Mushroom Grow Kit
Pleurotus ostreatus var. columbinus
One of the fastest gourmet mushrooms you can grow at home. Cut the bag, mist the air around it, and you can be harvesting dense blue-grey clusters within 7 to 10 days.
- Net weight
- 1.8 kg
- First harvest
- 7-10 days
- Ideal temperature
- 10-20°C
- Harvests per kit
- 2-3 flushes
- First flush
- up to 400g+
Setup: how to start growing
Five minutes of work, then it is just misting and watching.
Step 1: Open the box
Cut along the dotted line on the box.
Tip: use scissors for a clean opening.
Step 2: Create the growing zone
Cut a 3cm cross (X) on the front of the bag. Do not fold back the corners.
If pins have already formed inside the bag, cut your X directly over them.
Important: do NOT remove the plastic wrap. It is what keeps the block from drying out.
Step 3: Find the right spot
A normal room with some air movement is ideal — indirect light, no cold drafts and away from heating vents.
A bathroom, or a spot near a humidifier, works very well for keeping moisture up.
Step 4: Mist to keep humidity high
Mist the air around the block every 2-3 hours during the day, aiming for 3-7 mistings per day.
Avoid soaking the caps directly — water sitting on the mushrooms causes yellow patches.
Harvest: when and how to pick
Blue Oyster moves fast. Check twice a day once the caps start expanding.
Step 5: Check for readiness
Blue Oyster mushrooms are ready when:
- Caps have expanded to a good size but the edges are still curled slightly downward.
- Colour has lightened from the deep blue-grey of young pins to a lighter blue-grey.
- The cluster feels firm, not floppy.
Harvest before the cap edges flatten and curl upward — that is the sign the mushroom is about to release spores, which lowers quality and leaves a fine white spore dust on nearby surfaces.
Step 6: Harvest technique
With clean hands, grip the cluster at its base, twist gently and pull it away from the block. It should come away cleanly.
Remove any leftover stumps with a clean knife, as they can rot and affect the next flush.
Step 7: Storage tips
Store fresh Blue Oyster in a paper bag (not plastic) in the fridge for up to 5-7 days.
For longer storage, slice and dehydrate, or sauté and freeze in portions.
Post-harvest routine
What you do in the week after picking decides how big the next flush is.
Step 8: Resting period1 week
After harvesting, let the block rest for about one week. Keep it in the same spot and keep the plastic wrap on.
Do NOT water during the resting period. The mycelium needs time to recover — thanks to Blue Oyster’s fast growth, this rest is shorter than for slower species.
Step 9: Rehydration (optional)6-12 hours
Leave the block in its bag, cover with clean cold water and weigh it down if it floats.
Soak 6-12 hours, never longer. Drain completely, leaving no standing water in the bag, then return it to the growing spot and resume misting.
Next flushes: keep growing
Each kit has more than one harvest in it.
Step 10: Subsequent flushes
New mushrooms usually sprout near the site of the previous harvest.
Expect 2-3 flushes in total from each kit, and each flush typically produces a smaller harvest than the one before.
Avoid these mistakes
- Never remove the plastic wrap — it dries the block out.
- Avoid cold drafts, dry air and heating vents.
- Do not let the surface dry out between mistings. Blue Oyster grows fast and needs consistent humidity to keep up.
- Do not grow it in a sealed cupboard or closed cabinet. A normal room with some air movement is ideal.
What to expect
A typical Blue Oyster kit, day by day. Warmer rooms run faster, cooler rooms slower.
- 1Days 1-3
Adjusting
Nothing visible — the mycelium is adjusting to fresh air.
- 2Days 3-5
First pins
Small blue-grey pins start clustering around the cut.
- 3Days 5-8
Rapid growth
Caps expand fast — one of the quickest-growing mushrooms you can grow at home.
- 4Days 7-10
Harvest
Caps expanded, edges just starting to flatten. Check twice a day once caps start expanding: Blue Oyster can go from perfect to past its best in under a day.
Expected yield
Yields vary with room conditions, so treat these as a guide rather than a guarantee.
1st flush
up to 400g+
2nd flush
40-70% of first
3rd flush
Smaller again
if conditions are good
Cooking tip
Blue Oyster has a delicate, savoury flavour with a subtle briny note and a wonderfully meaty texture once cooked.
Tear into pieces and sauté in a hot pan with a little oil or butter for 3-4 minutes, until the edges turn golden and crispy. Season with salt, pepper and a squeeze of lemon.
Troubleshooting
Most problems come down to humidity or fresh air. Start here before getting in touch.
- Yellow or slimy patches?
- Water is sitting on the caps. Mist the air around the block, not directly onto the mushrooms, and improve air flow.
- No pins after 7 days?
- Move it to a slightly cooler spot (10-20°C) and increase fresh air.
- Pink or green mould?
- Stop misting that area and contact us for help.
- Mushrooms are tiny?
- More fresh air. Avoid cabinets and closed spaces.
- Block seems dry?
- Soak it for 6-12 hours, then resume normal care.
Did you know?
Nutrition powerhouse
Blue Oyster mushrooms are naturally low in calories and fat, while offering a good source of protein, fibre and B vitamins — a genuinely healthy addition to any meal.
Speedy grower
Blue Oyster is one of the fastest-growing gourmet mushrooms in the world — from pinning to harvest in as little as 5-7 days, quicker than almost any other variety.
Kitchen favourite
With a delicate, subtly savoury flavour and a tender yet meaty texture, Blue Oyster is a chef’s favourite for stir-fries, soups and pan-searing.
100% natural
Our grow kits use sustainably sourced hardwood substrate with no chemicals, pesticides or artificial additives.
Safety and storage
Safety information
- Cook thoroughly before eating. Do not eat raw.
- Mushroom spores may cause respiratory irritation in sensitive individuals. Harvest before the caps flatten and ventilate the room.
- Do not consume if you see green, black or pink mould, or if there is a sour or unpleasant smell.
- Keep out of reach of children and pets.
- Wash hands after handling the substrate.
- Not suitable for anyone with a mushroom allergy.
Storage before you start
- Living product. Start within 4 weeks of delivery.
- To delay, refrigerate (2-5°C) for up to 2 months.
- Do not freeze. Keep out of direct sunlight.
Net weight: 1.8 kg · Pleurotus ostreatus var. columbinus
Still need help?
Please contact us before leaving a review — we are always happy to help you get a harvest out of your kit.