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Oyster Mushroom 'Black Pearl King' - 2.2KG Ready To Fruit Block

Oyster Mushroom 'Black Pearl King' - 2.2KG Ready To Fruit Block

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Thick, scallop-cut stems and caps so dark they read black on the plate.

Black Pearl King (Pleurotus spp.) is a Japanese hybrid — King Oyster (P. eryngii) crossed with Pearl Oyster (P. ostreatus). It takes the thick stem, dense flesh and bold savoury depth from its king parent, and the fast colonisation and easy side-fruiting from its pearl parent. You get King Oyster texture on the plate without King Oyster fussiness in the grow room.

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 cool and humid, and the block does the rest.

Why growers and chefs chase this one

King Oyster stems, oyster-easy growing

Meaty stems. None of the eryngii fuss.

True King Oyster is notoriously demanding to fruit well. This hybrid inherits the thick, dense, caramelising stem — cut it into rounds and it sears like a scallop — while fruiting from a simple side cut the way every other oyster in our range does. That combination is the whole point of the cross.

Caps that read near-black

Darkest in the cold.

Deep charcoal to almost black, with rippling cap margins that lighten as they mature. Colour is driven by cool temperatures and consistent light — fruit it at the low end of the range and you get the dramatic near-black clusters that sell themselves on a market table or a menu.

You decide the shape it grows

More air, wider caps. Less air, thicker stems.

Airflow is a dial on this variety in a way it isn't on the others. Restrict fresh air and the stems elongate and thicken into a king-style column. Open it right up and the caps expand into a broad, layered oyster fan. Same block, two very different products — chosen before you start fruiting.

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

  • Stems with real substance — thick enough to cut into rounds and sear, holding their shape in the pan
  • Charcoal to near-black caps with rippled edges — the most striking cluster in the range
  • A firm, resilient bite and bold, earthy flavour with a faint sweetness and a hint of smoke
  • Noticeably better fridge life than a standard grey oyster — the dense flesh holds up
  • Control you don’t get elsewhere — adjust airflow and steer the harvest toward stems or caps

Why the hybrid behaves the way it does: P. ostreatus is a vigorous wood decomposer — fast to colonise, forgiving, and happy to pin from an opening in the bag. P. eryngii is the opposite: a grassland species that in the wild feeds on plant roots rather than wood, which is why it demands so much more control in cultivation, but also why it builds that famously dense, low-moisture flesh. Black Pearl King is a cultivar selected to carry the eryngii fruit structure on the ostreatus growth habit. The Masters Mix underneath it does the rest — hardwood supplies the lignocellulosic backbone, soy hulls add readily available nitrogen and protein, and the extra nitrogen is what fuels thick stems rather than thin, watery ones.

Why airflow changes the shape: Mushrooms read CO₂ as a depth cue. When CO₂ builds up around the block, the fungus behaves as though it’s buried and pushes the stem upward to reach clear air — stems elongate and thicken, caps stay tight. When fresh air is plentiful and CO₂ falls, it reads the surface as reached and invests in cap expansion instead. Most varieties treat this as a fault to be avoided; on Black Pearl King it’s a deliberate lever. Decide which form you want before you start fruiting, then set your airflow to match and leave it there.

Why cool and bright makes it black: Cap pigmentation in this cultivar develops most intensely at the low end of the fruiting range and under a consistent daily light cycle. Fruit it warm or in a dim corner and the caps come out a washed-out grey-brown — still perfectly good eating, but without the drama that makes this variety worth growing. Cool, bright and indirect is the recipe.

How to fruit your block

Site it cool → cut an X → pick your airflow → keep it humid → harvest pre-curl → rest → re-flush

Fruiting conditions at a glance

Fruiting temperature 13–20°C — a cool-weather variety, best in autumn, winter and early spring. It will not pin reliably above 20°C
For darkest caps 13–17°C with a consistent daily light cycle
Humidity 85–95% around the cut surface
Fresh air Your dial — plenty of air for wide open caps, restricted air for thick king-style stems
Light Bright but indirect, roughly 12 hours a day — never direct sun. Light drives cap colour
Time to first pins 5–8 days after cutting the block
Pin to harvest ~7–10 days
First-flush yield 450–550 g under optimal conditions
Total flushes 2–3 before the block is spent — fewer than a standard oyster, but heavier and denser per mushroom

Step by step

1. Find a cool, bright spot. 13–20°C with bright indirect light, out of direct sun and drying draughts. This is the one non-negotiable — above 20°C the block will sulk rather than pin. A cool spare room, garage, shaded verandah or cellar all work well through the cooler months.
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. Choose your form. For thick king-style stems, keep airflow low — tent the block loosely with a bag and vent it only briefly each day. For wide open caps, give it as much fresh air as you can while keeping the surface damp. Pick one and stick with it; switching halfway gives you neither.
4. Keep it humid. Mist around the cut 2–3 times a day so the surface stays damp but never waterlogged. Target 85–95%. If cap edges start cracking or drying, humidity is losing — mist more often or tent more closely.
5. Harvest pre-curl. Pins appear in 5–8 days and mature over ~7–10. Twist and pull the whole cluster from the base just before the cap edges flatten and turn up — that’s when colour is deepest, texture firmest and shelf life longest. A day early beats a day late. Don’t leave stumps behind.
6. Rest and re-flush. Clean off every stem stub, let the cut face rest and re-colonise for a few days, then bring the humidity back up. A second flush usually follows within 1–2 weeks, and often a third after that. 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 5–8 days · harvest ~day 12–18 450–550 g — the biggest and darkest flush of the block
2nd 1–2 weeks after the first harvest Typically smaller — cold-soak the block first to maximise it
3rd A further 1–2 week rest Lighter again, and usually the last worthwhile flush

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

🍳 In the kitchen

Bold, earthy and faintly sweet with a whisper of smoke, and a firm, resilient bite that holds up where a standard oyster would collapse. Cut the stems into thick rounds and sear them hard in a dry pan before adding butter — they caramelise and eat like scallops. Tear the caps into big pieces for grain bowls, tacos and stir-fries where you want each piece to carry visual weight. It takes high heat, long roasting and grilling far better than any other oyster in our range, and the near-black caps hold their colour on the plate.

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?

Black Pearl King is a strong margin variety for growers supplying restaurants — it commands a premium over standard oysters and travels better — and 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 (3 weeks for Pioppino and Reishi); we’ll confirm your dispatch date once the order is placed. Get in touch for commercial pricing and standing orders.

Perfect for

Restaurants and chefs after a mushroom with real structure · market gardeners wanting a premium point of difference · small commercial farms diversifying beyond grey oysters · home growers with a cool space and a season or two under their belt · anyone who has tried King Oyster and wants the eating without the equipment.

What’s inside the block

Australian hardwood pellets (Tasmanian Oak sawdust)
Soy hull pellets
Filtered rain water
Black Pearl King organic certified grain spawn (Pleurotus spp. hybrid)

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

More ready-to-fruit blocks

Variety Character
Pearl Oyster The benchmark — fastest to pin, highest yielding, endlessly versatile View
Blue Shimeji Oyster Deep blue-grey to charcoal fans — dark drama in a classic oyster form View
Snow White Oyster Pristine white clusters — elevates presentation on any plate View
Italian Oyster Heat-tolerant — the summer counterpart when Black Pearl King won’t fruit View

New to growing? Black Pearl King rewards a bit of experience and a cool space. If this is your first block, start with the Pearl Oyster Mushroom Kit — a more forgiving variety in a beginner-friendly boxed format.

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.

Black Pearl King is one of the more interesting things we grow — a variety that rewards a grower who pays attention, and one our restaurant customers notice the moment it lands on the bench. Whether you’re fruiting a single block in a cool spare room or running a rack of them through a market garden, this is the block we grow ourselves.

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