If you’re wondering how to grow oyster mushrooms—even on coffee grounds!—this simple guide will take you step-by-step. 🍄
Oyster mushrooms, also known as King Trumpets, are fast, easy, and inexpensive to grow. And it doesn’t matter where you live or what the weather is outside because unlike other plants, they don’t require sunlight.
You can grow them indoors in the middle of winter!
So whether you go the traditional route or use coffee grounds, this simple guide will take you step-by- step.
What Are Oyster Mushrooms?
Oyster mushrooms (Pleurotus ostreatus) are an edible fungi known for their delicate texture and mild, slightly sweet taste. They grow in clusters on decaying wood and can be found in the wild or cultivated for culinary use. Their name comes from their oyster-shaped cap and soft, velvety appearance, which ranges in color from white and gray to pink and yellow.
Commonly used in soups, salads, lettuce wraps, vegan casseroles, and more, they have a tender consistency that absorbs flavors well.
Beyond their culinary appeal, oyster mushrooms offer countless benefits. They’re rich in protein, fiber, vitamins, minerals, and antioxidants that boost health. They’re also an excellent source of heart-healthy, gut-healthy beta-glucans, as well as a compound called ‘ergothioneine’ that helps offset disease.
According to Dr. Michael Greger, “Of more than a hundred compounds measured in the bloodstreams of thousands of individuals, the one most associated with the lowest rates of disease and death was ergothioneine,”—a compound in mushrooms.
How to Grow Oyster Mushrooms—A Step-By-Step Guide
Here’s an easy step-by-step guide to growing oyster mushrooms at home. We’ll start with the conventional way then describe the coffee grounds method below.
1. What You’ll Need
- Organic oyster mushroom spawn.
- A clean bag or bucket.
- Straw or hardwood sawdust.
- A spray bottle of filtered water.
- A warm, dark space for incubation (65–75°F / 18–24°C).
- A well-ventilated, humid area for fruiting.
2. Prepare the Substrate
Chop the straw into small pieces or use hardwood sawdust. Pasteurize it by soaking in hot water (160–180°F) for about an hour to kill off unwanted bacteria and fungi. Drain and let cool.
3. Inoculate with Mushroom Spawn
Once the substrate is cool, mix in your oyster mushroom spawn. Distribute it evenly for the best growth.
4. Pack into a Container
Place the inoculated substrate into a clean bag, bucket, or container with small holes for air exchange. If using a bag, poke a few small holes in it for ventilation.
5. Incubate in a Dark Place
Store the bag or bucket in a warm, dark place (around 70°F). After a week or two, the mycelium (the fungal roots) will spread and turn the substrate white.
6. Move to Fruiting Conditions
Once the substrate is fully colonized, move it to a location with indirect light, fresh air, and high humidity (such as a bathroom or greenhouse).
7. Mist and Wait
Keep the environment humid by misting with water 2–3 times daily. Tiny mushrooms (pins) will start forming in about a week.
8. Harvest and Enjoy
When the mushrooms reach full size (caps about 2–3 inches across), twist and pull them off gently. Congratulations! You’ve just grown your own oyster mushrooms.
Keep in mind that you can also use mushroom growing kits that include all of the essentials.
Growing Oyster Mushrooms in Coffee Grounds
Growing oyster mushrooms in coffee grounds is a fun, eco-friendly, and innovative way to cultivate fresh fungi while repurposing waste. Coffee grounds are rich in nutrients like nitrogen, making them an excellent growing medium for mushrooms. It not only reduces food waste, it provides a sustainable, low-cost alternative to traditional substrates.
In addition, oyster mushrooms are particularly well-suited for this process because they thrive on organic waste materials and break them down efficiently. Plus, the setup is simple, requiring minimal space and equipment, making it an ideal project for home growers or urban farmers.
The result is a fresh, nutritious food source that contributes to a circular economy by turning waste into delicious, edible mushrooms.
1. What You’ll Need
- Oyster mushroom spawn.
- Freshly used coffee grounds (collected daily).
- A container or bag with small air holes.
- A spray bottle of filtered water.
- A warm, humid place for fruiting.
2. Collect Your Coffee Grounds
Used organic coffee grounds are an excellent growing medium since they’re already pasteurized by hot water. Let them cool completely before use.
3. Mix in Mushroom Spawn
In a clean container or bag, mix your oyster mushroom spawn with the coffee grounds. Each time you add fresh grounds, mix them in well.
4. Keep it Moist and Aerated
Store the mixture in a warm, dark space and mist it lightly with water every day. The mycelium will spread over the coffee grounds in about 2–3 weeks.
5. Maintain Humidity
Mist regularly to keep humidity high. In about a week, small mushrooms will begin to appear.
6. Harvest and Enjoy
When the mushrooms are mature, twist them off gently and enjoy your fresh, homegrown oyster mushrooms! 🍄
Pro Tips
1. Choosing the Right Strain
- Select a strain suited for your climate (e.g., Pink Oysters thrive in warm temperatures, while Blue Oysters prefer cooler conditions).
- Experiment with different varieties to see what works best in your setup.
2. Selecting the Best Substrate
- Common substrates: Straw, hardwood sawdust, coffee grounds, cardboard, coco coir, vermiculite, gypsum, and agricultural waste (e.g., corn husks, cottonseed hulls).
- Pasteurize straw or agricultural waste to reduce contamination risks.
- Supplement sawdust with bran or gypsum for increased yield but be aware that it may increase contamination risks.
3. Sterilization & Pasteurization
- Use hot water (65–80°C for 1 hour) or cold water lime soak (12–24 hours) to pasteurize straw before inoculating.
- Fully sterilize hardwood sawdust and supplemented substrates using pressure sterilization (15 PSI, 90+ minutes).
4. Proper Inoculation Techniques
- Work in a clean environment to prevent contamination.
- Mix spawn evenly into the substrate and pack it loosely in grow bags, buckets, or containers with air holes for airflow.
5. Ideal Incubation Conditions
- Temperature: 20-24°C (68-75°F)
- Humidity: 80-90%
- Darkness: Oyster mushrooms don’t need light during colonization.
- Airflow: Ensure gas exchange by using breathable bags or poking small holes in plastic containers.
Fruiting
6. Fruiting Stage Optimization
- Introduce fresh air and increase humidity when the mycelium fully colonizes the substrate.
- Ideal fruiting conditions:
- Temperature: 15-22°C (59-72°F)
- Humidity: 85-95%
- Fresh air exchange: At least 3-5 air exchanges per hour
- Light: Indirect or ambient light (6500K LED or natural daylight)
7. Managing Humidity and Airflow
- Use a humidity tent or grow chamber to maintain moisture.
- Misting is essential but avoid over-saturating the mushrooms.
- Keep airflow consistent to prevent spore buildup and contamination.
8. Harvest at the Right Time
- Harvest when the mushroom caps start to flatten but before they curl upwards.
- Use a sharp knife or twist off clusters gently to avoid damaging the mycelium.
9. Preventing Contamination
- Always clean your hands, tools, and workspace before handling spawn.
- Remove any moldy or contaminated substrate immediately to prevent spread.
10. Maximizing Multiple Flushes
- After the first harvest, soak the block in cold water for 12-24 hours to rehydrate.
- Keep humidity high and wait for new pins to form.
- Most substrates produce 2-3 flushes, but some can yield more.
Growing Oyster Mushrooms From Stems
You can also grow oyster mushrooms from other oyster mushrooms. Start by selecting fresh mushrooms with intact stems. Cut the stems, leaving about an inch attached to the base. Prepare a growing medium such as pasteurized straw, coffee grounds, or sawdust, and place the stem pieces inside.
Keep the medium moist but not soaking, and store it in a warm, dark place for about a week until white mycelium begins to spread. Once colonization is visible, transfer the substrate to a humid environment with indirect light and fresh air.
Within a few weeks, small mushroom pins will appear, growing rapidly into full-sized oyster mushrooms ready for harvest.
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The medical and health topics covered on the PlateofGrass website have not been evaluated by the FDA and are not intended to prevent or cure any disease. This article and its content is presented ‘as is’ for informational purposes only.
