How clean do things have to be?

I am interested in growing mushrooms indoors, but the sterilization and pasturization requirements just seem so overwhelming to me! 

I decided the simplest thing would be to start with a few kits, so I ordered two oyster and one shitake kit from Fungi Perfecti.  The oyster kits immediately grew lots of green mold, and I ended up throwing them in the compost pile. 

Then I read that one cubic inch of typical household air contains about 100,000 particles of pollen, spores, and mold.  Good grief.  How can I possibly get things clean enough?  It just seems impossible. 

I have read Stamet's book, but I'm struggling to apply it to a small-scale, low budget mushroom operation. 

I can innoculate inside a glove box, but how can I keep my growing room clean enough?  Do I really need to set up a sterile grow room (with no drywall, no wood, positive air flow, etc.)?  Does it have to be that complicated?

Sterile culture is very difficult, especially for beginners. If a  commercial oyster mushroom kit was contaminated so quickly inside your house, then your place must have a lot of problems. I've grown mushrooms for about 20 years now, and because I'm not into obsessive cleanliness, I've always avoided sterile culture- one mistake and your whole project is ruined. I suggest that you start with King Stropharia- the mushroom that is the easiest to grow. Try to get natural spawn from a local friend who has had success with King Stropharia- just transfer several big chunks of mycelium into a bed of hardwood chips/ sawdust that are being used as mulch around fruit trees or vines. This species will also grow well on straw. I've found that Raspberries make the best companion plant for King Stropharia. If you can't find natural spawn, order freshly- made spawn from Field and Forest Mushrooms in Wisconsin. I've had almost no success with spawn from Fungi Perfecti- I love Paul Stammet's books and other products, but I just don't buy spawn from them anymore. (Spawn must be freshly made, never buy spawn that's been refrigerated for more than a few weeks.) After you master King Stropharia, I'd try log culture next- regular oysters and shiitake on fresh oak logs work well. Once you succeed with log culture of shiitake and regular oyster mushrooms , then  you can try sterile culture on a small scale. (Just my two cents...) Good luck!!

What kind of oyster kit did you get? At what point did the kit grow mold?


oyster mushrooms by frankenstoen, on Flickr

A fully colonized block of oyster mycelium will not grow mold, if the environmental conditions are correct. Cleanliness is not important once the substrate is colonized. A sterile growroom is not necessary once you reach the fruiting stage.

What is important at this stage are environmental conditions. Oysters need high humidity (about 90% RH), lots of fresh air (6 to 12 complete air exchanges per hour), indirect sunlight, and a temperature ideally between 50 and 70 degrees Fahrenheit. If you give them these conditions, they will thrive. Healthy oysters eat bacteria and mold for lunch.

If the mycelium become stressed because of too little oxygen, too little moisture, too high of temperature, etc. then its immune system breaks down, and pathogens attack, and it becomes sick. If the environment favors the pathogens, then the pathogens will flourish.

Its really not that hard, if you can get your hands on a pressure cooker and make yourself a glovebox (about $20 in materials and a hour or so of work) you should be able to handle oysters. I am not a very clean person (verging on "crusty" to be honest) and my house is full of mold spores and i have ~ a 90% success rate with sterile culture.  have fruited oysters about a dozen times, never had a failure. I teach mushroom classes and one part of it is inoculating a milk jug of oysters, so far people have been reporting a 75% success rate. I'm working on some super easy methods for oysters, to help people get going with mushroom cultivation. Mostly right now i'm focusing on a tek that uses a modified 5 gallon bucket and a clear plastic garbage bag. I'm still trying the method myself, so it will be a couple months before i've got my tutorial written, but it seems like one step better then my curreny favorite of the milk crate draped with plastic bag.

PS I have a huge amount of respect for paul stamets and i wouldn't know 1/2 the stuff i know about mushrooms if it weren't for his excellent books. BUT, i have heard VERY mixed things about the quality of fungi perfecti's kits and spawn. Please don't get frustrated because of some trouble starting with mushroom cultivation. Just keep that mycelium running and feel free to message me with questions.

As to the quality of Fungi Perfecti kits, I have only purchased two - the oyster kit and the shiitake kit - and I have to say, both kits worked perfectly for me and produced excellent results. My success with these kits led to me learning more and more and eventually growing hundreds of lbs. of mushrooms over the past few years. I eat home-grown mushrooms every single day of the year.

I have had a lot of failures - A LOT OF FAILURES! - since my successful start. And I have to say, I have learned so much more from each of my failures than I have from my early successes. There are so many, many wonderful ways to fail, and in each failure there is a new lesson to be learned (as well as the recurring lesson of humility). Success, on the other hand, often teaches us very little and makes us cocky and arrogant.

Would I have continued had my early experiments started off as failures? I don't really know. But I sure hope I would have!

Frankenstoen, I ordered the Pearl Oyster Mushroom (Pleurotus ostreatus) kit.  UPS left it on my porch, and when I picked up the box I felt a wet spot, so I'm assuming they had set it in  a pile of snow/slush at some point.  It was soaked through the cardboard to the kit itself.  Within days, it began growing green mold at that site, and also around the skewers I jabbed into the kit to support the plastic tent. 

Since it grew around the skewers, I'm assuming the green mold was already in my house and that the wet spot and jab site just gave it an entry to the kit?

Fungi Perfecti sent me a replacement kit (happily and promptly, I should add).  They told me not to put it in the same room the first kit had been in, so I put it in a bedroom on the other end of the house.  It immediately grew a fine crop of green mold all over.

I think I did really well with the temperature, light level, misting, etc.  However, I did notice that you say in your post that the kits need good air flow.  Seems to me like that wouldn't have happened, since it had a plastic tent on it, per their instructions.

I wish I had a bit of success right out of the gate to encourage me, but I'll keep trying on my own.  No more money spent on kits!

Peachlovingman, I guess the reason I gravitated toward indoor growing is because I like the idea of being able to grow year-round rather than have one large flush outdoors.  Also, I'm sort of intrigued by the idea of mushrooms spilling out of laundry baskets, plastic bags, etc.  The process really interests me.

I guess you're right about my house having "problems."  I am neat (no clutter) but not necessarily clean.  None of us have any allergy/cold things going on, but I guess our house could have mold without me knowing it.  That's normally not a problem where we live, though. 

Anyway, I'll look at the website you suggested, and order some sawdust spawn for outdoor growing.  I'll let you know how it goes.

Does the King Stropheria taste good?  It doesn't look that appealing, I guess because of the size. 

Maine Aaron, my fellow crusty friend.  My plan is to follow some of the instructions I've seen on-line and in books for homegrown pyslocybes.  The reason I'm looking at those techniques is because they are more small-scale, do-it-yourself than Stamet's techniques.

I scored a great pressure cooker at the dump and was able to order a new seal and owner's manual on-line.  I also have tons of canning jars, and I picked up some Tyvek and micropore tape for inoculating through small holes in the lids.  I put together a spawning box with two Rubbermaid containers and an aquarium heater.  I will put a glove box together, too.

I'm just about ready to take a shot at it.  I just need to order some organic rye and the spore syringe.

Like I said, it just sort of freaked me out when both my kits grew mold.  It made the whole process seem impossible.  I appreciate the encouragement, and I will message you with questions as I go.  thanks!

I'll just mention that there are no degrees of sterility. It's either sterile or it isn't.

I think I did really well with the temperature, light level, misting, etc.  However, I did notice that you say in your post that the kits need good air flow.  Seems to me like that wouldn't have happened, since it had a plastic tent on it, per their instructions.

I do think the tents that come with the kits are crap, and I have to admit that I didn't use them. Instead, I made a "shotgun" growing chamber - basically a large tote with holes drilled in it and wet perlite on the bottom. This is a picture of my Fungi Perfecti kit fruiting in it:


Shiitake mushroom block by frankenstoen, on Flickr

Eventually, I made this "greenhouse" growing chamber out of plastic shelves, an ultrasonic humidifier, and two small fans on timers - one fan sat on top, blowing fresh air down inside, and the other fan sat on the bottom, recirculating air up through the entire chamber:


fruiting chamber by frankenstoen, on Flickr

I added two fluorescent cool white shelf lights, at the top and in the middle, to provide light for the mushrooms.

This chamber worked absolutely perfectly. Too perfectly, in fact.

It turns out, growing mushrooms in your house is a TERRIBLE IDEA. After a month and a half of mushroom harvests, my cats and I were coughing, sneezing, and wheezing from the spores. I had no idea how bad it was until I tried doing some sterile agar work in my kitchen and all of my petri dishes contaminated with spores from the mushrooms in the fruiting chamber. Spores, especially oyster spores, are a health hazard when encountered in great numbers. I moved my chamber outdoors (something I could do, because I lived in the Pacific Northwest, with its mushroom-friendly climate,  at the time).

I'll just mention that there are no degrees of sterility. It's either sterile or it isn't.

Yes, that is true of sterility, but there are different levels of cleanliness.

Absolute sterility is very important if you are canning food. You don't want botulism or anything else contaminating your food.

I have found that sterility is not necessary for any part of the mushroom-growing process. It just has to be "good-enough". The cleaner one's "lab" is, the easier agar work and grain inoculation are, and the greater the chances of success. Cleanliness makes everything so much easier.

It's a numbers game. The more mold spores in the air, the quicker they contaminate a sterile growth medium. The less time a petri dish is left uncovered, the smaller the chance that a spore will land on it. (A good way to determine the amount of mold spores in your house is to uncover a petri dish of agar for a short period of time in various rooms, then put the lid back on and incubate for a couple of days.)

If a room is really clean, and I keep the air still, I can pour 50 petri dishes and not have a single one contaminate. Sometimes, a couple of dishes will contaminate. On a really bad day, maybe half will contaminate. Even if four-fifths contaminate, that's still ten good dishes. So a dirty "cleanroom" will mean more wastage- time and supplies wasted. But ten good dishes could inoculate 100-200 quarts of grain jars. So it's not a complete loss. It is possible to grow a lot of mushrooms from a less-than-sterile laboratory, it's just more work.

Idahofolk, I like growing King Stropharia outdoors with the "Natural" culture method because it fits in well with my philosophy- keep it simple and keep it cheap, as well as the do-nothing natural farming methods of Masanobu Fukuoka. I have managed to naturalize the King Stropharia strain sold by Field and Forest on my farm in Oregon's Coast Range and make it a perennial. It fruits several times during the summer when other mushrooms are not easy to find around here. I think the flavor is good, especially when the mushrooms are well-cooked by sauteing them in oil with onions, herbs, garlic, tamari and homemade brandy or wine. They never seem to have any maggots in them either, unlike oyster mushrooms which act as maggot magnets the second the spores mature! Slugs and sowbugs nibble on them, but nothing like with some other species. Also, I've never seen a King Stropharia get as big or as inedible as the classic photos by Stammets where he has the little boy holding a massive 5 pounder.  Which kinda' sucks, since I love BIG mushrooms, (especially King Boletes and Morels!!!) Every spring, I chip up branches in my old chipper/ shredder machine and use the chips as mulch around berries, vines, fruit trees, and the young conifers (which I'm using as a privacy screen). Today I transferred mycelium chunks from underneath a Currant bush and stuck them in the fresh mulch underneath my Blueberries. Another thing I like about King Stropharia is that they also eat Douglas-fir chips, which is a very common tree around here. I'm hoping you can naturalize King Stropharia in your climate and make it a perennial, too. I'm just not sure how cold it gets in your climate...

What is the pressure cooker for? What do you mean by “glovebox?”

The pressure cooker is used to sterilize grain that is used to make mushroom spawn, the white fluffy stuff that is used to inoculate logs, wood chips, compost, etc. Here is a video by Freshcap Mushrooms about how pressure cookers are used in mushroom cultivation:



A glove box is a sterilized chamber where lab work is done- typically transferring liquid culture or pieces of mushroom to an agar  (nutrient) plate. The glove box is also used to  transfer agar or liquid cultures onto sterilized grain. A glove box is made from a clear plastic tote that has two holes cut into it. Inside the holes, two rubber gloves are glued to perform the sterile work with. By using the glove box, airborne contaminants are kept out of the project. Nowadays, many people use self-sealing jar lids and syringes for transfers, or they use HEPA filters.