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Grey Oyster (Pleurotus ostreatus) is the classic oyster mushroom variety—the one you'd find growing wild on hardwood trees in nature. It thrives in temperatures between 50-80°F, making it one of the most adaptable varieties for year-round indoor growing. With a firm texture and delicate, sweet flavor, it's prized by chefs for its versatility in everything from stir-fries to risottos.
How to get started
Using a clean knife, cut a 3” x 3” ‘X’ into one side of the bag—it’s okay to cut into the sawdust! You’ll likely see white, pink, or yellow growth inside, which is healthy mycelium. If you notice green fuzzy mold, reach out for support.
Fill the included sprayer with filtered or distilled water and mist the cut area at least twice daily, or more often in dry conditions. Keep up this routine, and tiny mushrooms (“pins”) should appear in a few days. If not, you can loosely cover the block with a hole-punched bag to boost humidity.
Watch your mushrooms grow! Be sure to mist your mushrooms every day to keep them moist. You may need to mist them twice a day if you’re in a dry climate. As your mushrooms grow, keep an eye out for signs that they’re ready to be harvested. Refer to our harvesting guide below for more information!
Harvest when caps begin to flatten and edges start to curl upward. Grey Oysters are best when picked young—as they age, the flesh becomes tougher. Twist and pull entire clusters from the base, or cut with a clean knife. Don't leave stems behind as they can invite contamination.
After first harvest, rest the block for 7-10 days without misting. Then submerge the entire block in clean water for 12-24 hours (we use a cooler or large bowl). Drain completely and resume regular misting. Second and third flushes typically appear within 1-2 weeks and can be just as productive as the first.
Grey oyster mushrooms are among the fastest-growing varieties, usually producing their first harvest in 3-5 days after fruiting begins. You’ll start to see small pinheads form within the first week, and they’ll rapidly expand into full clusters just a few days later. Ideal fruiting conditions are 70–75°F (21–24°C) with high humidity (85–95%) and good airflow to help the mushrooms develop their signature broad, curling caps.
This is a common beginner issue caused by high CO₂ levels or low airflow. Grey oysters need plenty of fresh air exchange to form wide, healthy caps. If your mushrooms look leggy, open your fruiting chamber or tent more often, increase air circulation, or add a small fan nearby (not directly on your mushrooms) to keep air gently moving. Maintaining high humidity while improving airflow usually fixes the problem quickly.
Yes — most oyster grow kits can produce 2–3 flushes of mushrooms. After harvesting, gently remove leftover stems, mist the surface lightly, and continue maintaining humidity and airflow. The block may rest for about a week before producing the next flush. Each harvest is smaller than the first, but all are just as delicious and fresh.
