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Grey Oyster Mushroom Growing Guide

Grey Oyster (Pleurotus ostreatus)

Grey Oyster mushrooms (Pleurotus ostreatus) are the most widespread type of oyster mushroom and can be found across the world. This species is very forgiving to cultivate, and a great option for both beginner and experienced home growers. When the mushrooms first start pinning they’re a lovely dark grey-blue, fading to light grey as they mature. Grey Oysters like a lot of air exchange and will grow large caps under the right conditions. When fresh air is limited they stretch and produce longer stems rather than big fan-like caps (you want to avoid this as the stems tend to be quite tough). They are found either in clusters of smaller mushrooms, or as individual larger mushrooms, with broad, thin, fan-shaped caps and crowded gills that run most of the way down the stem.

Fruiting months: All year round

Pinning Temperature: 10°C – 16°C

Pinning Humidity: 95% – 100%            

Fruiting Temperature:  15°C – 21°C

Fruiting Humidity: 85% – 95%

Cultivation Difficulty: Easy    

                                                                                              

Fruiting Instructions

Grey Oyster mushrooms fruit easily and readily. While 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. Pour it out after a few minutes.

Step 2: Cut open the plastic at your chosen spot (see tip below). Cutting an “X” shape is best as 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 an overlay of mycelium has already grown under the plastic, in the form of bumps or bulges. These are good spots to choose for this step. If there is no sign of pins forming, wait for a week or so, and if you still don’t see any bumps or buldges, choose a spot with the most concentrated mycelium.

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

Tip: Soaked perlite helps to create the optimal humid environment for mushrooms to thrive, and we recommend using it to get the best results from our grow sticks. All our fruiting chambers are supplied with dry perlite, but it is also readily available at most nurseries.

Grey Oyster Tip: The Grey Oyster mushroom likes a lot of fresh air so we recommend our countertop or macramé fruiting chambers for optimal fruiting conditions. If you don’t have one, use a plastic tray or plate.

Step 4: To avoid possible contamination, clean the chamber with soap and water, and rinse it thoroughly.

Step 5: Place the grow stick in the fruiting chamber. Make sure that the fruiting site is positioned in a way that the 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 reasonably 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 not direct sunlight. Avoid drafty areas such as those next to open windows or doors as this will dry out the grow sticks. A closed-off room that has a stable temperature is best.

Step 6: Using a spray bottle, fine-mist 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 fine 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 pour more water into the perlite.

Harvesting

Like all oyster mushrooms, Grey Oysters should be harvested just before the edges of the caps start to curl upward. A good sign to look for is the curling up of the cap edges on the largest mushrooms in the cluster – as soon as they do this, harvest straight away.

  • Grey oysters should be harvested all at once, in their clusters.
  • Wash your hands with soap and water before harvesting.
  • Gently grip the base of the cluster and with a twisting and pulling motion carefully separate the mushrooms from the substrate of the grow stick.
  • Try not to take too much substrate off the grow stick.
  • Tape up the hole with some clear packaging tape as neatly as possible with 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.

These mushrooms have a longer shelf-life than pink and golden oysters, but for best nutritional and culinary results, cook them within a few days of harvest.

Caution: If you let your mushrooms grow for too long before harvesting they will drop spores. When your mushrooms drop spores it dramatically decreases their quality.

Culinary Notes

Grey Oyster mushrooms have a slightly sweet taste with a woodsy characteristic. Compared to shiitake mushrooms they have a milder and more tender flavour profile. The stems should be cut away as they are tough even when cooked. Once cooked they have a tender texture, especially when fried, roasted, or grilled. Braising and sautéing will bring about a softer texture.

Grey Oysters are versatile and substitute well into many mushroom recipes. They are a fantastic meat replacement for stir-fries and go particularly well in egg dishes like omelets or quiches. They are a delicacy often used in Japanese, Korean, and Chinese cuisine.

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