how are edible mushrooms grown - shiitake growing on log

How are Edible Mushrooms Grown?

Growing edible mushrooms requires different methods for different mushrooms. You can grow the common button mushroom from grocery stores on compost. Shiitake mushrooms can be grown on sawdust or in your backyard on logs. Oyster mushrooms can be grown on just about any medium from used coffee grounds to old sofa pillows.

Choose the Type of Mushroom You Want to Grow

Button Mushrooms

Button mushrooms are the small white mushrooms most commonly found at grocery stores. They are sapophytic meaning they eat by consuming dead decaying plant material.

Cremini and portobello are the brown versions of white button mushrooms. Originally they were discarded but a market eventually developed when people got bored of just white mushrooms. Portobello are simply brown cremini mushrooms that have fully opened. To learn to grow button mushrooms is to learn to grow cremini and portobello.

Button and cremini make great cooking mushrooms to add to soups. casseroles, and as side dishes.

Portobello are one of, if not the best, mushroom for making a whole food, high protein, high fiber plant-based veggie burger. No more mushy bean and quinoa burgers. Learn to grow your own crisp, delicious portobello burgers right at home!

Shiitake Mushrooms

Shiitake mushrooms are most common in east Asian cuisine. I first discovered them working at a Japanese restaurant. They’d be delivered in these small open boxes which would go right in the fridge. Little did I know at the time how much went into making them.

Shiitake are wood consuming mushrooms. You can grow them on logs (most common commercially) or sawdust (easiest for growing at home as a dining room centerpiece).

They are larger and have a more firm texture than button mushrooms. They can also be dried then cooked into stews for a completely new flavor profile.

Oyster Mushrooms

Oyster mushrooms are the pigs of the grown-at-home mushroom world. You can fatten them up on just about anything. They’ll grow on used coffee grounds, compost, old sofas, and even diesel contaminated soil.

Oyster mushrooms were once used in a soil cleanup challenge where they consumed all the diesel in a pile of soil from a spill site. They were more effective than the other forms of standard treatment for this type of spill. Plus they created an edible by-product that contained non of the diesel or other petroleum contaminates originally in the soil (they ate it!).

Oyster mushrooms have a very light texture. They do well in stir frys but for me, they are just fun to grow. Growing edible mushrooms on used coffee grounds just feels awesome. Waste not want not!

The next three sections will cover step by step how to grow button mushrooms, shiitake mushrooms, and oyster mushrooms. Youtube video tutorials will be included for each so you can watch or read, whichever you prefer.

How to Grow Button/Cremini/Portobello Mushrooms on Compost Terrariums

Tools and Equipment You Need for Button Mushrooms

  • Button Mushroom growing kit or spawn
  • Shallow rectangular container with a lid (1′ x 2′ by 6 inches deep)
  • Compost
  • Manure

If this is your first time growing button mushrooms we highly recommend you do so with a mushroom growing kit. With this kit you’ll get safe, clean mushroom spawn. You can make that on your own later but it’s a more advanced technique that requires sterile equipment and procedures. Mushroom contamination is easy to do so let someone else do this step.

What is a mushroom growing kit?

Mushroom growing kits include a growing media that has already been fully grown out with mushroom mycelium. Often you simply change the conditions slightly and mist daily to get this to fruit immediately. This is the easiest way to grow mushrooms at home.

Using a mushroom growing kit is similar to buying baby pepper plants. You didn’t have to germinate and care for them while young and you’re much faster to getting to harvest.

We recommend you start with a mushroom kit for quick wins right in the beginning.

What is mushroom spawn?

Mushroom spawn are similar to buying vegetable seeds. It’ll be up to you to add these to a clean growing medium. Then you’ll wait for the mushroom mycelium to spread throughout the media. Then you’ll change conditions to inspire mushrooms to fruit.

This is a bit more work but you get more mushrooms for your investment. We recommend you try to grow from spawn after successfully getting mushrooms to grow from a mushroom kit.

Button Mushroom Growing Steps (from spawn)

1. Mix 1 part compost with 1 part manure. Mist this mixture. Stir with a sterilized metal spoon (sterilize with rubbing alcohol). Mist and stir till the entire mixture is moist but not wet.

2. Fill your container with this mix so it’s at least 6 inches deep.

3. Sprinkle the mushroom spawn from on top.

4. Cover and store at room temperature.

5. Check and mist daily.

6. It’ll take a 3-4 weeks for the mushroom spawn to grow through the substrate.

7. Once the medium looks fully grown out with white mushroom roots (mycelium), add a thin layer of sterile soil. This is the step that will inspire mushrooms to fruit.

8. Continue to check and mist daily. After another 3-4 weeks your mushrooms should start fruiting.

How to Grow Shiitake Mushrooms on Logs

Tools and Equipment You Need for Shiitake Mushrooms

  • Shiitake Mushroom plug spawn
  • Logs – 3-6 inches in diameter and 3-4 feet long, freshly cut
  • Drill with drill bits that are the same size as the plug spawn
  • Rubber mallet
  • Cheese wax

Shiitake Mushroom Growing Steps (from spawn)

1. Drill holes 3 inches apart scattered over the surface of the logs. About 30 to 40 holes per 4 foot long log.

2. Use the rubber mallet to hammer the plug spawn into the holes.

3. Seal the holes with hot cheese wax. Cheese wax is less likely to crack at lower temperatures compared to beeswax.

4. Use extra wax to seal scarred or broken bark areas (to prevent infection of other types of mushrooms).

5. Choose a location so they will be in the shade for most of the day. (north side of a building). You can also cover them with burlap or similar to shade them.

6. Stack them in sets of 4. Lay down four logs side by side. Then lay 4 more on top cross-stacked. Keep adding layers and making piles till you’ve used up your logs.

7. Watering isn’t needed. They will draw moisture from the logs. This is why you use fresh cut logs. Only water if there is a drought. Rain water will also naturally keep them moist.

8. Wait 8-18 months for the spawn to fully grow through the logs. Check the ends of the logs. When you see white mycelium mushroom roots at the ends they are ready for fruiting.

9. Logs should eventually fruit (form mushrooms) on it’s own. If not you can shock them.

10. Shock non-fruiting logs by soaking them in cold water for 24 hours. You can use a pond or stream as long as nighttime temperatures are above 50F.

11. After shocking, lean the logs against a wall or stack them together in an A-frame shape. This will inspire them to fruit. Fruiting starts with the appearance of small mushroom pins on the surface of the log. Pins eventually fruit into full mushrooms.

12. Mushrooms will be ready 7 to 10 days after shocking.

13. Logs can be fruited for up to 3 seasons or more.

How to Grow Oyster Mushrooms on Used Coffee Grounds

Tools and Equipment You Need for Oyster Mushrooms

  • Oyster mushrooms from the store (get ones with stems)
  • 91% Isopropyl alcohol
  • Bowls
  • Plates
  • Razor blade
  • Coffee grounds
  • Coffee filters (large)
  • Tyvek sheets. Tyvek lets air in and CO2 out but has smaller pore space and reduces contamination from green mold.
  • Pint sized mason jars with lids (just the lid rings). Use smaller jars for fast growth which helps prevent contamination.
  • Gallon ziploc bags
  • Bale of Straw

Oyster Mushroom Growing Steps

1. Sterilize the bowls, plates, and razor with 91% isopropyl alcohol

2. Cut off the bottom of the stems from the mushrooms with the sterile razor. Place them into a sterile bowl or plate. Feel free to eat the remainder of the oyster mushrooms. You only need the very bottom of the stems. See video for what this should look like.

3. Make a full pot of coffee. When the grounds are warm (not hot or cold) taken them out and squeeze the filter with grounds in the sink to remove excess water. It’s important to use fresh grounds as these will essentially be sterile. Don’t let them get cold as they could get infected with other mushrooms.

4. Rip up the filter and stir together with grounds into a sterile bowl.

5. Sterilize the inside and outside of a mason jar and one lid. Let air dry.

6. Sterilize one large coffee filter. Let air dry.

7. Add sterile coffee grounds and sterile straw in a 1:1 ratio to the jar just enough to fill the bottom 1 inch. Sterilize straw by cutting into 1 inch pieces then boiling in water for 20 minutes then letting cool. The straw will speed up inoculation time helping to reduce green mold infections.

8. Add oyster stem stubs to coffee. Make sure mycelium side (bottom) is down. Use sterile knife to flip them over so bottom is down if needed.

9. Add sterile tyvek sheet to the top and screw on lid. Don’t use the sold portion of the mason jar lid. Just use the ring.

10. Store at room temperature in a dark place. Wait 8 days. Check that mycelium roots have grown throughout the coffee.

11. Once the roots are fully grown, make a new batch of coffee (just enough to cover with an inch of new coffee). Wait for the grounds to cool then add to the jar. Wash your hands with isopropyl first and use a new sterile coffee filter to seal the jar.

Note: Don’t add too much coffee. This will cut off oxygen to the mycelium which slows growth and could lead to infection.

12. Keep adding coffee grounds every time the mushroom spawn has colonized the last batch of coffee. It should take 4-6 weeks to fully fill the jar and get everything colonized.

13. Check for green mold (Trichoderma spp.).  See part 2 video below for example. If you see it toss out that jar.

The green mold could spread spores that will infect your other jars. Try adding sterile used coffee grounds slower and making sure you get full mycelial growth (white roots of mushrooms) all throughout coffee before adding new grounds.

14. The final step is to mix your oyster mushroom spawn with sterile straw.

15. Chop up straw in a food processor till it’s 1″ pieces or smaller. Fill a 5 gallon bucket of chopped straw. Use a protective mask outside while doing this (it generates small particles you don’t want to breath in).

16. Heat water up to 190 F. Add this to the bucket of straw. The water/straw mixture should be at least 160 F. Hold it at that temperature for 1.5 hours (by covering with blankets to hold in the heat and adding more boiling water if needed). This will pasteurize your straw.

17. Strain out water. Use a sterile salad spinner to squeeze out more water (sterilize with isopropyl alcohol).

18. Sterilize table top and ziploc bags (inside and out) with isopropyl alcohol.

19. Wipe outside of oyster spawn jars with alcohol.

20. Scoop out spawn with sterile spoon and break up into smaller pieces.

21. Add layer of sterile straw to bag then a thin layer of spawn. Repeat till bag is full of layers of straw and spawn. Pack it tightly down (make sure hands are clean by washing with alcohol).

22. Squeeze out excess air then seal bag.

23. Use a sterile razor, cut 1″ x’s on the sides. That’s where the mushrooms will fruit out.

24. Within 14-20 days the oyster mushrooms should full grow through straw and you should see pins growing out the side slits.

25. When pins start to form mist the bag on the outside twice a day. Add a humidifier next to the bags if you are in a dry area.

26. Full mushrooms should be complete 7-8 days after pins first appear.

26 steps is a lot! If you use a mushroom growing kit you essentially skip steps 1 through 23. That’s why we recommend you start with a kit then do the above later when you’re ready to go deeper.

Full videos of the method described above can be found if you scroll below.

What to do if you keep getting green mold contamination while growing oyster mushrooms

If green mold contamination keeps being an issue for your oyster mushrooms do the following:

  • Use smaller jars. Faster growth means less time for contamination
  • Use fresh used coffee grounds. Don’t let them cool.
  • Start many batches at once. More batches increase the chances of having successful batches.
  • Throw out contaminated batches immediately.
  • Grow in a different location. Your chosen room may have a source of green mold. Try a new location.
  • Wash your hands frequently with isopropyl alcohol during checking and mushroom work. Keep things clean!
  • Wash the area frequently with isopropyl alcohol. OCDs and mushroom growing are a match made in heaven!
  • Use tyvek sheets instead of coffee filters to seal the jar lids. Tyvek has smaller pore spaces so it reduces contamination while allowing air flow.
  • Add sterile straw in with the coffee while growing. This speeds up grow time which reduces exposure to green mold infection.

Growing Oyster Mushrooms on Coffee Grounds Part 1

Growing Oyster Mushrooms on Coffee Grounds Part 2

Growing Oyster Mushrooms on Coffee Grounds Part 3

How to Grow Wild Mushrooms

Some types of wild mushrooms can be grown at home, or in your back yard rather. This is a much more advanced technique as they are wild for a reason – they do not prefer human cultivation.

Still, chanterelles and morels and other wild mushrooms can be urged to grow outside if you maintain proper conditions which will be explained in another article on growing wild mushrooms.

Frequently Asked Questions (FAQ)

What is Mushroom Spawn?

Mushroom spawn refers to mushroom mycelium (roots) that you purchase from a supplier. You use these to inoculate mushroom growing medium which in turn will grow mushroom fruits.

What is a Mushroom Growing Medium?

Mushroom growing medium refers to the “soil” of sorts that you use to grow mushrooms. This medium could be sterile straw used to grow oyster mushrooms, wooden logs for shiitake, or compost and manure for button mushrooms.

What are Edible Mushroom Growing Kits?

Mushroom growing kits give you a quick start to growing mushrooms at home. They already include and fully prepped growing medium. All you typically have to do is spray with water, keep in a suitable humid location, and wait for your mushrooms to sprout.

This is the shortcut we recommend you do for your first batch of mushrooms. Once you’ve mastered this you can move on to growing mushrooms from scratch. These easiest mushrooms to grow from scratch are oyster mushrooms. See  complete instructions and videos above.

What Conditions are Needed for Mushrooms to Grow?

Mushrooms require sterile mushroom media, 70-80% humidity, room temperature, and dark conditions to grow then light to fruit. Maintaining these conditions are vital to preventing infection of your mushrooms. See detailed steps above for growing oyster mushrooms as an example of how to maintain these conditions.