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Black Pearl Oyster Growing Guide

Black Pearl Oyster (Pleurotus ostreatus)

Black Pearl Main Image
Younger Black Pearl
Close up Black Pearl


The Black Pearl Oyster (Pleurotus ostreatus) is a hybrid between European and Asian Pleurotus ostreatus that comes from Japan. They are much easier to grow than their finicky cousins – the King Oyster – and although they tend to look quite similar when starting out, as they mature they look more like the Grey Oyster with lighter caps.

Unlike other oyster mushrooms, black pearl oysters have a long shelf life and can be kept in the fridge for up to two weeks after harvesting.

Black pearl oysters are like a perfect mixture between regular oyster mushrooms and king oysters. They produce a decent sized stem and a lovely round cap. Even though the stem is larger, they tend to grow in clusters. They are a bit less picky about their placement in your house, although you still want to make sure there is as little draft as possible with a stable temperature.

Fruiting months: Winter

Pinning Temperature: 10°C – 16°C

Pinning Humidity: 95% – 100%

Fruiting Temperature:  15°C – 21°C

Fruiting Humidity: 80% – 95%

Cultivation Difficulty: Easy – Medium

Fruiting Instructions

Black Pearl Oyster mushrooms fruit easily provided the correct conditions are provided. Various methods can be employed to fruit them successfully, the following is a tried and tested guideline:

Step 1: Remove the cotton wool plug from the grow stick and fill the hole with a small amount of water. After a few minutes you can pour it out.

Step 2: Cut an X-shape (fruiting site) in the plastic at your chosen spot (see below for a tip!). Each cut should be roughly 5cm long. Don’t cut more than one X and make sure to use a sharp knife or pair of scissors.

Tip: Often pins have already formed under the plastic and look like small bumps or bulges. These are good spots to choose for the next step. If there is no sign of pins forming, try to make your opening close to the hole of the grow stick. 

Step 2: Cut open the plastic at your chosen spot (see the tip below!). Cutting an “X” shape is the best, because it’ll keep your pins a bit covered and therefore keep their environment sufficiently humid. You can also just cut the plastic away completely and expose the mycelium, but make sure you keep the exposed area wet enough.

Tip: Often pins or overlay has already formed under the plastic and look like small bumps or bulges. These are good spots to choose for this step. If there is no sign of pins forming, it is best to wait (up to a week) to see if you get any overlay or pins forming under the plastic. If you still don’t see any pins, you can try cutting at a spot that has a lot of concentrated mycelium. Make sure this spot is close to your soaked perlite, and keep it well hydrated (especially with this species!)

Optional Step 3: Put your perlite in a colander or sieve and run some cold water over it before adding it to your fruiting chamber. Once it’s in the chamber, you can even add a little extra water to make sure it’s soaked through.

Tip: Soaked perlite is extremely useful to help create the optimal humid environment for your mushrooms and we recommend using it to help you get the best results from our grow sticks. We supply perlite with all our fruiting chamber options but it is also readily available at most nurseries.

Tip: The King Oyster mushroom likes limited fresh air so we recommend keeping it in a closed off room while fruiting. If you do not have one of our fruiting chambers you can use a plastic tray or plate instead.

Step 4: To avoid possible contamination, clean your chosen fruiting chamber with soap and water, rinse it thoroughly and let it dry.

Step 5: Place the grow stick in your chosen fruiting chamber. Make sure that your fruiting site is positioned so that your mushrooms will not be obstructed by any part of the fruiting chamber as they grow, and that they are as close to the water or soaked perlite as possible.

Tip: Consider carefully where you place your mushroom kit as this will affect how well they grow. Try to find a spot that receives plenty of ambient light but is out of direct sunlight. Avoid drafty areas such as those next to open windows or doors as this can dry out the growsticks. A closed off room that has a regular temperature is best.

Step 6: Using a spray bottle set to a fine mist, spray your grow stick from about 30cm away.  Misting 2 – 4 times per day is enough to keep your mushrooms happy! Before work, when you get home, and just before bed should be sufficient but an extra misting would be beneficial if you’re at home.

Tip: Try to spray so that the mist falls over the grow stick and perlite rather than spraying directly at the mushrooms. It’s ok for the mushrooms to get slightly wet but remember that the aim of misting is to maintain a humid environment for them. Use your mister to rehydrate the perlite if it feels dry, and don’t be afraid to add some more water to the perlite at any stage.


When to harvest is up to the cultivator’s preference, although younger black pearl oysters do tend to have a better flavour and texture. A good way to tell when to harvest is the colour change and upward curling of the caps. Black pearl oysters have a much better shelf life than other oyster mushrooms and can be kept in the fridge for up to two weeks after harvesting.

  • Black pearl oysters grow in clusters.
  • Wash your hands with soap and water before harvesting
  • Lightly grip the base of the cluster and with a twisting and pulling motion carefully separate it from the substrate of the grow stick.
  • Try not to take too much substrate off of the grow stick.
  • Tape up your hole with some clear packaging tape as neatly as possible with as little chance for air to enter the gaps.
  • Check out our guide on how to get a second flush out of your grow stick – The Second Flush.

Caution: If you let your mushrooms grow too long before harvesting they will drop spores. When your mushrooms drop spores it dramatically decreases their quality and it can be dangerous to your lung health if this happens too often.

Culinary Notes

These mushrooms have a similar texture to the other oyster mushrooms, though their stems tend to be a bit tenderer than other varieties. They have a unique flavor with a lovely peppery aftertaste. Their strong taste means they can do well even when cooked with other strong ingredients.

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