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Oyster Mushroom 'Blue' - 2.2KG Ready To Fruit Block

Oyster Mushroom 'Blue' - 2.2KG Ready To Fruit Block

$24.00
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The most cold-hardy oyster in the range — thriving exactly when the others slow down.

Blue Oyster (Pleurotus ostreatus var. columbinus) is the classic cool-season oyster — prized by commercial growers for thick, meaty caps, steel-blue colouring and rock-solid performance right through the cold months when other varieties struggle to fruit cleanly. It's a close cousin of Pearl Oyster, but bred for the cold: where Pearl tops out around 22°C, Blue Oyster keeps pinning and fruiting down to 12°C.

This is a 2.2 KG ready-to-fruit block: fully colonised, sealed, and ready to pin as soon as you cut it open. Grown, sterilised and colonised right here on Tamborine Mountain on our own hardwood + soy hull Masters Mix — not imported, not repackaged, not resold. Cut an X, keep it humid, and you'll have mushrooms in about a week.

Why Blue Oyster earns a spot in the range

Built for the cold

Fruits cleanly down to 12°C.

Where most oyster strains stall out below 16°C, Blue Oyster keeps pinning and fruiting through the coldest part of autumn, winter and early spring. If you're growing outdoors or in an unheated space over winter, this is the block that keeps producing when others won't.

Thick, meaty caps

Denser flesh than Pearl.

Blue Oyster caps are noticeably thicker and meatier than Pearl's — steel-blue to slate-grey when young, softening to grey-brown as they mature. The extra density holds its shape better under searing, grilling and heavier cooking methods.

Firm, savoury flavour

Richer than Pearl, meatier than Shimeji.

Where Pearl is mild and Blue Shimeji leans nutty, Blue Oyster brings a firmer bite and a deeper, more savoury flavour — closer to a meat substitute than a delicate garnish. A favourite with chefs building plant-based mains.

Grown and colonised on-farm

Not repackaged. Grown here.

Every block is mixed, sterilised and colonised at Kai Kai Farm on our own hardwood + soy hull Masters Mix — the same substrate we fruit commercially. Verified contamination-free, consistent block to block, and packed to order rather than sitting in a warehouse.

What you'll notice

  • Pins forming within about a week of cutting the bag, even in cool conditions that would stall other varieties
  • A dense first flush of thick, steel-blue-grey caps — 500–600 g under good conditions
  • Multiple harvests from a single block — keep the humidity up and re-flush up to four times
  • Firm, savoury mushrooms that sear, grill and braise better than most oysters
  • The most cold-tolerant grow in the range — ideal for outdoor or unheated winter growing spaces

Why Masters Mix drives strong oyster yields: Hardwood provides the lignocellulosic backbone — the cellulose, hemicellulose and lignin that oyster mycelium evolved to digest. The soy hull fraction adds readily available nitrogen and protein, which fuels denser mycelial growth and heavier flushes than pure hardwood alone. Every block is sterilised and fully colonised in controlled conditions before it leaves the farm, so the mycelium arrives established and primed — all it's waiting for is air, light and moisture.

Why Blue Oyster fruits at lower temperatures: The columbinus strain carries genetics selected over generations to pin and develop proper fruiting bodies well below the range most oysters need — without the misshapen caps or long, thin stems that cold weather causes in warm-adapted strains. That's why it keeps producing cleanly through the months when Pearl and other standard oysters slow right down.

How to fruit your block

Site it → cut an X → keep it humid → harvest pre-curl → rest → re-flush

Fruiting conditions at a glance

Fruiting temperature 12–18°C — the coldest-tolerant oyster in the range, at its best through the cooler months
Humidity 85–95% around the cut surface
Fresh air High — good airflow gives tight, well-formed caps
Light Bright but indirect — never direct sun
Time to first pins 5–7 days after cutting the block
Pin to harvest ~5–7 days
First-flush yield 500–600 g under optimal conditions
Total flushes Up to 4 before the block is spent (2 recommended for commercial operations)

Step by step

1. Site your block. Bright, indirect light at 12–18°C, out of direct sun and drying draughts. Because this variety tolerates cooler conditions so well, an unheated shed, garage, shaded patio or outdoor set-up over autumn and winter all work well.
2. Cut an X in the bag. With a clean, sharp knife, cut a 5–8 cm "X" through the plastic on one face of the block — or directly over any pins already forming. Mushrooms fruit from the cut. One or two cuts per block is plenty.
3. Keep it humid. Mist around the cut 2–3 times a day so the surface stays damp but never waterlogged. Blue Oyster wants 85–95% humidity — in dry weather, tent the block loosely with a perforated plastic bag to hold moisture in.
4. Give it fresh air. Oysters need good air exchange to form proper caps. Too little airflow (high CO₂) produces long stems and small caps; a well-ventilated spot with daily fresh air gives tight, meaty clusters.
5. Harvest pre-curl. Pins appear in 5–7 days and mature over ~5–7 days. Twist and pull the whole cluster from the base just before the cap edges curl upward — for the best texture, deepest colour and cleanest presentation. Don't leave stumps behind.
6. Rest and re-flush. Keep misting after harvest. A second flush usually follows within 1–2 weeks, then a third and fourth in succession — each a little smaller. To boost later flushes, submerge the block in cold water for a few hours, drain, and continue.

What to expect from each flush

Flush Timing What to expect
1st Pins in 5–7 days · harvest ~day 10–14 500–600 g — the biggest flush of the block
2nd 1–2 weeks after the first harvest Typically smaller — cold-soak the block first to maximise it
3rd–4th Successive 1–2 week rests Progressively lighter, until the substrate is spent

Yields vary with temperature, humidity and airflow. The figures above are typical for a block fruited in good conditions.

🍳 In the kitchen

Firm, meaty and savoury, with noticeably thicker flesh than Pearl or Snow White. Best cooked rather than eaten raw — it sears beautifully, holds its shape in stir-fries and soups, and works well as a plant-based meat substitute. Some cooks pick up a faint umami or mild seafood note when it's pan-seared hot in butter. Cook it hot and fast for a firm bite, or slow-braise for a heartier, richer dish.

Storage & handling

If you can't fruit straight away, store the sealed block somewhere cool and dark below 18°C for up to 2 weeks. Handle it gently — the mycelium inside is alive and ready to go. Leave the bag sealed until you're ready to start fruiting; once you cut the X, the clock starts and the block wants humidity and air.
📦 Shipping in warm weather: We strongly recommend adding Express Post during the warmer months to minimise heat stress in transit — add one per block to your cart.

Ordering for a farm or a kitchen?

Blue Oyster is the natural choice for growers wanting reliable cold-season production — bulk pricing is available from 10 blocks. Orders of 4 or more blocks of a single variety are made to order and can take up to 2 weeks (5 weeks for Chestnut and 10 weeks for Shiitake); we'll confirm your dispatch date once the order is placed. Get in touch for commercial pricing and standing orders.

Perfect for

Small commercial farms and start-ups · market gardeners and farm-to-table producers · home growers wanting a robust, cold-season variety · outdoor and unheated-space growing over autumn and winter · restaurants and chefs harvesting unique produce on-site · workshops and educational demonstrations.

What's inside the block

Australian hardwood pellets (Tasmanian Oak sawdust)
Soy hull pellets
Gypsum + Chalk to buffer pH
Filtered rain water
Blue Oyster organic certified grain spawn (Pleurotus ostreatus var. columbinus)

~2.2 KG block, sterilised and fully colonised with Blue Oyster mycelium before dispatch. No fillers, no additives — just substrate and mycelium.

More ready-to-fruit blocks

Variety Character
Pearl Oyster The benchmark oyster — mild, fastest-pinning, high-yielding View
Blue Shimeji Oyster Not to be confused with Blue Oyster — dense clustered fans, blue-grey to charcoal, nuttier flavour View
Snow White Oyster Pristine white clusters — elevates presentation on any plate View
Italian Oyster Heat-tolerant — fruits successfully when the others won't View

New to growing, or after a smaller starter? The Pearl Oyster Mushroom Kit is a forgiving beginner-friendly boxed format from the same range.

The Kai Kai Farm story

Kai Kai Farm is a family operation on Tamborine Mountain in Queensland's Scenic Rim. We grow gourmet mushrooms commercially — oysters, lion's mane, pioppino, chestnut — and we sell blocks cut from the same production we fruit ourselves.

We're growers, not resellers. Every block is mixed, sterilised and colonised here on the mountain, using methods refined over years of commercial gourmet and medicinal mushroom production. What arrives at your door is genuinely fresh — inoculated, colonised and packed to order, with verified contamination-free cultures and full transparency from substrate to shelf.

Whether you're fruiting one block on a kitchen bench or running a rack of them through a market garden, this is the block we grow ourselves. It's the one we'd hand a first-timer, and the one our commercial buyers keep coming back for.

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