Oyster Mushrooms On Coffee Grounds

I have wanted to inoculate coffee grounds with oyster mushrooms for quite awhile. With the help of the cool people at Wild Joe’s, I have managed to collect some great organic, free trade coffee grounds. The grounds are too rich to waste and the folks at Wild Joe’s  feel the same way! Oyster Mushrooms grow on almost anything, so it stands to reason they would like coffee grounds. The very strength of coffee grounds, is also their downfall.They are a perfect semi sterile substrate for growing fungus because they have been steam pasteurized. The problem with that is the quickest fungus to get to them is usually green mold. The trick to this project is going to be controlling the growing conditions to help the oysters while making the mold unhappy.When I first put the spawn in the coffee grounds, the spawn took off because it was warm in the garage and the spawn was hungry. Then I noticed the green mold creeping in, and as you see in the pictures, there is a major war going on between the mold and the oysters.

Coffee Grounds From Wild Joe'sOyster Spawn on Coffee GroundsOyster Spawn on Coffee GroundsOyster Spawn on Coffee GroundsOyster Spawn on Coffee GroundsOyster Spawn on Coffee Grounds

The little brown specks are the grain from the spawn mixture. The white spider web is the Oyster spawn growing and the green is, you guessed it, mold.At this point the project has gone outside,and neither the spawn nor the mold is happy! But I know the spawn is still growing as the temperature is just above freezing, and the mold won’t survive the cold.Hopefully the bucket will produce mushrooms. Either way the experiment has already told me that Oyster spawn does indeed like coffee grounds.

Thanx again to the awesome crew at Wild Joe’s for saving the grounds for me,and thank you Hannah for setting it up. Stop by their coffee house on Main Street in Bozeman and create some grounds for us.

34 thoughts on “Oyster Mushrooms On Coffee Grounds”

  1. Yes, the experiment was successful and the mycelium won the war. They were some of the best tasting oyster mushrooms I have ever tasted. Check out the oyster mushroom pictures on the homepage.

    Check out the harvest on the July 2009 link.

  2. I tried putting the inner parts of Oyster Mushrooms in Coffee Grounds. In 2 to 3 days time White mycelium grows. But after another day or two it stops. What could be the reason?


  3. Hello,
    Thank you for your question. There are a lot of variables in growing mushrooms. Without knowing specifics, my guess would be moisture. Did the coffee grounds dry out? I have had a tough time getting the moisture right on coffee grounds. They are not as forgiving as other growing mediums. Sometimes the mycelium goes underground, so to speak, and is difficult to detect. Don’t give up on it, I have walked away from projects to have them flush without my help. Let us know how you do.

  4. Hello, and thank you for your comment. I have been only using coffee grounds. It works with or without the coffee filters! I try to get them inoculated before they mold. If I were to mix with anything, it would be straw or wood chips.

  5. Hi, I have been trying to grow Pohu oyster mushrooms in coffee grounds, but I am not very impressed with the rate of growth, especially compared to their growth on box Elder chips/sawdust. Do you think it could be the variety? what type of oysters did you plant?

  6. Try drying out your coffee grounds by baking them first. Then remoisturize with 10% hydrogen peroxide. The peroxide stops the mold but not established mycelium. The peroxide will kill fungi spores so you can’t use it it to start out your mycelium.

  7. Hello, And thank you for your comment.
    I don’t recognize the variety “Pohu”. I will look it up, but does it go by a common name? I have been using the Pleurotus ostreatus sawdust spawn from Fungi.com (link on homepage). This is considered the tree oyster and it grows wild around here. There is quite a difference in strains as far as how they grow and flush. My biggest issue was getting the moisture just right. Too much and they molded, too little and they didn’t flush. Good luck and let us know how you do.

  8. Great Tip!
    This could be used on a large scale also. Do you grow, or just know?
    Thank you for the tip, and keep them coming!

  9. Hey, I just hopped over to your web page using StumbleUpon. Not somthing I would typically read, but I enjoyed your thoughts none the less. Thanks for making some thing worthy of reading through.

  10. Hi, Dean! Really informative. Thanks! How did you go about finding and purchasing the oyster mushroom spawn?

  11. Hello and thank you for your comment!
    I have purchased spawn from
    You also can wrangle spawn from the wild. The part where the mushroom is attached to the tree will usually Jump to coffee grounds.
    Let us know how you do,

  12. Thanks, Dean! Unfortunately, as it showed up on my screen it only said “I have purchased spawn from” and then it goes blank. I think I will go with Fungi Perfecti as they seem to be one of the most reputable firms out there. Thanks again for the how-to!

  13. I agree with using Fungi Perfecti for spawn. Paul Stamets runs a great company and has done much for the mushroom community.
    There is a link to his retail website on my homepage.

  14. I have a second batch of Oyster ‘shrooms growing out of the one side (package bought from Back To The Roots), and I have one HUGE Oyster “trumpet” (that’s what it looks like to me… the inside is open) growing, plus a couple smaller ones. However, white stuff is growing on the big one (at the base and from the inside) and I’m not sure if that’s white mold and thus harmful to the ‘shroom and/or us, if we eat it…


  15. The mycelium of the oyster mushroom is white. The spores are also white and usually get all over everything. The mold I see is usually green! Without seeing it, that would be my guess at what you are seeing. What are the oysters growing on (substrate)? It is not uncommon to have a large mushroom growing along smaller ones.

  16. I am growing on grounds in a plastic tub the mycil ran rampant throught the coffer grounds and now seems to have broken up into 1/2 inch balls of mycl and grounds and the whole tub is involved , they look like little black specked marbles…ever seen this before? they have stalled at this point in the cycle and have been like this for a month and a half now. I recently put the tub under a plastic dome and put down these cloths that hold lots of water and the humidity went from 25 to 60+. I spritz water on the substrate every couple days and the cloths a little more often. got any other ideas for me like soaking or refrigerating or anything. the temp in my room is 65 – 70 farenhiet thanks in advance for any tips

  17. Hello, and thank you for your comment.
    Most Oyster mushrooms do require a a cold temperature to start flushing. They will need to be cooled to 50 degrees or cooler for a few days and then put into a room temperature setting. In nature oysters flush in spring and fall and rest when it is hot out. They start flushing when the night temps are around 50.They also need bright light to flush properly. Low light or high CO2 levels cause long stems and tiny caps. You are learning the little tricks that nature does for us unnoticed. Let us know how you do,

  18. How about starting with vermiculite and brown rice flour mix ted with coffee grounds in a jar. vermiculite holds water well to get it right soak it in water and wring it out with a paper towel if u have a substrate ull want to cover it with an inch layer of vermiculite. If its not staying wet put a spray shield in our box don’t spray substrate diretly put up plexiglass to shield it. Get humidity to 70-75% temp 70-80 f . can use a bubbler from an aquarium n bubble water in bottom of terrarium. Vaults of erowid has a lot of info. It maybe for psylosybin but same idea. My first time with oysters I’ll let u know Gna try white n black morels inside and out any tips? Substrate mix? I’m going from spore syringe. I hear grass seed and hard wood chips? I like the brown rice flour, vermiculite and h2o. Thanks, Q

  19. Thank you for your comment.
    Morels like some type of burnt wood in the mixture, especially outside. Oysters will grow on almost anything, but remember most varieties need a cold snap to flush. Please let us know how you do,

  20. drilled some wooden dowels into my 4 ft logs of poplar my mushrooms blue oysters i let them sit for 10 months then i soaked them for 2 days i got some results but nothing to talk about on 6 logs i harvested 10 grams of dried product so i let them sit for another 8 months how can i increase my yield i drilled 50 dowells per log help

  21. Hello, and welcome to Montana Mushrooms!
    I will try to help you, but I will need to ask a couple questions.
    What is the diameter of the logs?
    Were they freshly cut when you doweled them?
    Were they shaded and kept moist during fruiting?
    Often times the second fruiting is as large or larger than the first. You might just need to soak them again and make sure the conditions are as good as possible for fruiting. The Blue is a cold weather shroom, so i would try in early spring or late fall.
    Let us know how you do

  22. I am just starting to grow oyster mushrooms, on coffee grounds and card board. Have grown Shitakes on logs for serveral years. Just getting info right now. This site is well put together, and informative…..

  23. Welcome to Montana Mushrooms and thank you for your nice comment!
    I have been growing oysters on coffee grounds for several years, and will try Shitake on logs this year!
    I am not sure how they will grow outside in Montana, but I should be able to grow enough to eat.
    What do you think?

  24. Hi Dean,
    Just a thought… what about adding some hydrated lime to the coffee grounds? Mold doesn’t like alkaline casing. I’m wondering if it’s ok to use the lime to keep mold from growing.

  25. Hi Frank,
    I think you are on to something! I think it would work just fine as long as you watch that the pH level doesn’t get too high. I have always suspected the high acid content of coffee grounds makes it easy for the mold to grow. Maybe a lime bath would be a great way to kill the mold and adjust the pH.
    Let us know if you try this and thank you for your suggestion.

  26. Did you use rye grain as your grain spawn. I just built six coffee plus additives “logs” using inoclulated blue oyster rye berries. My question is. As with straw it should take two weeks to colonize. Is it the same time frame for oysters? And usually how fast is the bounce back time for the inoculated rye berries before the mycellium starts to colonize my substrate?

  27. Hello, and welcome to Montana Mushrooms!

    I used rye grain spawn for that batch. Coffee grounds colonize much slower than straw. The moisture content is tricky!
    Happy growing,

  28. hello sir, now i am growing oyster mushrooms on coffee grounds but i found white worms inside the bag and in another i found green mould.what is the reason for both ? let me know how to prevent green mould and worms in coffee grounds.

  29. Hello and I apologize for the late answer.
    About the only way I know to control either is to put them outside.

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