The Fruiting Environment: Chosing a Grow Room Design for Home Cultivation
One of the most important aspects of growing mushrooms indoors is providing the right fruiting environment. Unless you have adequate temperature, humidity and air exchange, your mushroom block will dry up and not produce any fruit.
Providing adequate air exchange while maintaining high humidity is difficult to master, but there are several possible solutions that will get the job done.
Although different mushrooms have their own unique environmental requirements, once you have a basic grow area set up you can tailor it to the specific species you are trying to grow.
Straw logs hanging in the grow room.
When trying to design a grow area, think what causes mushrooms to fruit in nature- that is, high humidity and cool temperatures. That is why you see way more mushrooms outside in the fall when the rain is falling and cooler temperatures have settled in.
Two other aspect that are not as obvious is the requirement for a high rate of air exchange, or more specifically low levels of carbon dioxide, and the proper light levels. Most mushrooms don’t grow well in the dark and require a threshold level of light to produce normal fruits.
As for air, high levels of fresh air can be difficult to achieve when trying to maintain high humidity, and some experimenting will be required on the part of the home cultivator.
The Cheapest Option: The Shotgun Fruiting Chamber
Anyone just getting into the hobby might want to start with a shotgun fruiting camber. It is essentially a clear plastic tote that looks as if it was blasted with a shotgun, hence the name. This design is good for the small scale cultivator who just wants to fruit one or two small blocks, or a few PF cakes.
A good fruiting environment can be maintained in a SGFC, but it requires a little more monitoring and maintenance.
Start by getting a clear plastic tote that is big enough for whatever blocks you want to fruit. Drill holes in the tote two inches apart on all sides of the tote. This will allow the fruiting blocks or PF cakes to breath.
In order to produce and maintain humidity, fill the bottom of your SGFC with a few inches of perlite. Perlite is a porous rock like material that absorbs water. This water is slowly released inside your chamber which causes a humid environment. Before putting the perlite in your chamber, soak it in water for an hour so it can fill with water.
The last thing you will need for your SGFC is a spray bottle with a fine mist. Several times a day you will want to open the lid and fan to get some fresh air movement, and then spray water into the chamber. This should help to maintain high humidity. If you want to know where you are at, get a cheap hygrometer to monitor the humidity levels. It will also tell you the temperature. Keep your SGFC by a window or in room that receives a moderate level of natural diffuse light.
See full instructions on building a SGFC here.
The Dedicated Hobbyist Option: Mushroom Greenhouse Design
If you want to pump out a lot of mushrooms and want to be able to automate some of the process, you might consider stepping up to a mid size grow chamber. The most common type of indoor mushroom growing chamber is the 4 tier green house. This option will cost a little more, but is a great way to increase you mushroom growing potential.
The 4 tier greenhouse is typically used for starting plants indoors. They are very commonly found in garden centers, big box retailers or can be bought online for pretty cheap. You can even buy entire kits online- which saves picking up all the components individually. The 4 tier greenhouse can easily be converted into a mushroom growing paradise. It is big enough to hold several blocks, flat trays and lots PF cakes.
The main advantage of this design is the incorporation of the humidifier– which can be automated- and saves you from having to open the flaps and spray several times a day. You could just place the humidifier inside the grow chamber, and although that will easily maintain high humidity, you will still have to open the chamber several times a day to allow for fresh air exchange. A much better option is to pipe in the humidifier using a few pieces of PVC pipe.
The humidifier has a fan, which will push fresh humid air into your chamber.
When choosing a humidifier, you have the option of either a cool mist or a ultrasonic humidifier. Both will work, but the ultrasonic is a far better option. Ultrasonic humidifiers produce a visible stream of vapor, using spinning discs that vaporize water droplets, and can increase the humidity in your chamber really quick.
Cool mist humidifiers simply use a wick to draw water up and into an air stream and are much less effective. Make sure to clean your humidifier often to prevent contaminants from building up inside.
It is best to use a hygrometer in your grow chamber to monitor the humidity. You will not want to run the humidifier all the time, as it will will produce way to much moisture in your grow area. Typically, you will want to maintain at least 80% relative humidity. A good option is to get a timer that has multiple on and off setting, and playing around with your specific set up until you find a good on-off pattern.
If your grow chamber is placed on carpet or hardwood, make sure you place a sheet of plastic underneath so that the build up of moisture doesn’t damage your floors. Also, although the humidifier will pump in fresh air, it is not always enough, especially for air hungry species like blue oyster. You may still have to open up your chamber once in a while to fan in some fresh air.
The trick to a successful 4-tier grow tent is trial and error in order to figure out what set up works best for your specific area, season and type of mushroom.
Here are some things you might need. In particular, we have used the tear drop humidifier with mush success.
See what works for you!
Mushrooms require a specific balance of humidity, temperature, fresh air and light. The above options are good choices for the home cultivator, but you can get creative and come up with a design that works for your situation. Part of the fun of growing mushrooms at home is the experimentation. Post pictures of your set up below!
Thanks for reading and good luck with your grows!
I am looking for a good way of temperature control in a four tier greenhouse. Do you have any suggestions?
Hey Patrick thanks for reaching out! I usually just keep a 4 tier in the garage and the temperature stays pretty steady throughout the year. If not, you could always try a portable air conditioner and a small heater fan used to either heat up or cool down the room in which the 4 tier is placed. It would be heard to try and heat/cool a 4 tier directly, unless you too the extra steps to insulate it, which might not be worth the effort. Let me know how it goes though!
you could always use a hydro innovations heat exchanger with small 4″ inline fan with a small waterchiller/and water pump add a thermostat to fan. Walla closed loopchilling. with a 4″ dustshroom hepa air filter you can open loop exchange air and filter and cool at same time think ” three birds one stone”.
I had same problem with my greenhouse. I put an adjustable fish heater in a 2 liter plastic juice bottle after filling it mostly to the top leaving a 3/8 inch air gap at top and siliconed it in place. Then i bot some cheap foil faced sheet foam insulation and shored it and folded it around the greenhouse on all 4 sides and cut a separate piece to cover the top and bottom and punched holes for air lines to go thru. didnt take long at all and brought up temp about 4 degrees to 68- 70. If I moved the humidifiers inside it would raise into 70s easily, but king oysters require much fresh air and these temps seem ok.
Should read scored it not shored it
Do you not worry about changing the temp for Fruiting?
It’s not entirely necessary although it does help. Oysters in particular will fruit pretty good without a sudden temperature change. For commercial growing definitely, but for growing at home generally not needed.
Do you have a write up on how to setup a piped in ultrasonic humidifier to a GH tent like is done in the picture above?
Not at the moment, but I’ll sure put one up – stay tuned. The new set up I have with the 4 tier is a lot better. Using a 5 gallon bucket with a floating disc pond fogger, with humidity being pumped in through PVC pipe with a blower fan. Works like a charm!
Did you ever do a write up for this setup? I get what you’re saying, but where do you put the blower fan?
Not yet- I’ll get on it though! You can mount the fan anywhere, I mounted one outside the tent on a wood frame, then just used PVC to pipe it into and out of the bucket.
Also interested in this as I’m in the process of designing my own ecosphere.
Awesome. Thank you. I have a blower fan Set up but it doesn’t seem to be enough. I think I have to put a second fan up top inside and/or have it put air in more frequently.
We have opted for 4 tier greenhouse setup, but unfortunately we have encountered a lot of condensation and dripping. We are pumping in humidity with a simple humidifier/tube setup. Would you have any tips on keeping the humidity level in check?
Also, how exactly should we go about the inevitable pooling in the bottom of the greenhouse. I see in the picture above the seems to be a PVC frame wrapped in plastic? Is it meant to be emptied every so often? How exactly would we go about it with a similar setup?
Any and all help would be greatly appreciated.
Hey Gabriel, thanks for reaching out! A 4 tier mini grow chamber is a great choice! If the humidity is too high, try running it for less time, using an on/off timer. Also, you can try running it with the door unzipped all the way. The pooling at the bottom is an unfortunate result of the humid environment. Obviously, the best way to fix this would be to place the 4 tier over a drain. If you don’t have this option, you could use a large tote or tub place under the 4 tier to collect the water. You can either towel it out every-other day, or install a small drain and drain pan to collect the water. Not a perfect solution, but you’ll just have to find a way that works for you. Hope that helps!
Run the tubes into anywhere from 1 to 3 empty juice bottles . I run a tube from humidifier into bottle about a half inch.(laying on its side, cap on ) and run another tube out to the greenhouse. Mist condenses inside bottle and catches lots of the excess water. you can even run into and out of extra plastic bottles as required. just empty the condensate out every day or so. I melted holes into bottle for lines to enter with an appropiately sized socket i heated.
Hey, I had a greenhouse grower + humidifier + hygrometer, but my mycelium kept getting beat out by some green fungus that took over the environment before it was able to.
How do I create a more sterilized chamber/place to inject mycelium into the jars??
I am thinking that the problem might be not with the fruiting chamber, but in the creation of the blocks. Once the mycelium has fully taken over the substrate, it should be pretty resistant to contamination. You may need to re-evaluate the way you make your fruiting blocks to make sure there are no opportunities for contamination to get a foot hold before you start fruiting. As for the chamber, you can try spraying the walls down with a light bleach solution every few days (5% or less) and making sure you put fresh water in your humidifier every couple days. Hope that helps!
Hey, do you have more info on your new fruiting chamber build with the disc pond fogger, 5 gallon pail, fan, and piping it into your 4 tier grow chamber ?
Big thanks in advance !
Not yet, but I will put something up shortly. Feel free to get creative though! I basically just piped PVC into the fruiting chamber, and ran the line through a 5 gallon pail with a fan on a timer. Ill do a write up on it soon!
i’m planning to build a greenhouse for white oyster mushroom. what is the recommended temperature, humidity and carbon dioxide for such type mushroom?
can i utilize defective refrigerator for my greenhouse by installing exhaust fan, humidifier device and sensors.? thanks.
Hi James! Feel free to experiment, because ideal conditions will depend on the strain… but in general, 18-20 degC, and >85% humidity will be ideal for growing many types of Oysters. You could definitely try to build something out of an old refrigerator, but you can easily do with a less complicated set-up. All the best!
I want to do the same thing with an old pepsi fridge (3 walls in glass) how did you proceed??
Thank you so much for all of this! I’m struggling with the exhaust fan issue- I understand I need exhaust piping but what can you do with the air leaving the chamber short of making a hole in your house and pumping it outdoors? Not sure what to do about spores leaving the chamber?!?!?
For the exhaust, as long as you don’t have a ton of humidity exiting all the time, it shouldn’t be much of a problem, since the volume of your house is much larger than the volume of the grow chamber. For larger grow areas, pumping it outside is advisable. As for the spores, I have never found this to be much of an issue. Best practice is to harvest the mushrooms before they drop too many spores. You could also consider filtering the air leaving the grow chamber, although the grow chamber would have to be otherwise airtight for this to be effective.
Hope that helps!
I am running a small farm for oyster mushroom. the problem is the lighting. how much light can be allowed inside the room. if the room is completely sealed, what category of lighting will be preferable.
Thanks in advance.
Light is important, but not for the same reasons as plants, so it is not usually a huge concern. Best practice is to use florescent lights. I used 2 ballasts each with two 4 ft bulbs for a 4 ft x 8 ft grow chamber, and it worked out pretty good.
Hope that helps!
Contaminated blocks? That’s from not sterile enough substrate, pre-inoculation, or not having a sterile inoculation environment…if you think your substrate block is not the problem, the look at your inoculation…can you build a still air box? If so you can build ridiculously cheap, one time use, or a damn good one like mine out of a tote, some flanges, elbow leanth rubber gloves, window/door weather strip tape, and 91% alcohol…I’ve lost 3 jars in 54…that’s pretty good…I’d say that was more likely inoculation contam not substrate, since they were 3 different batches…
Also, another option is to build yourself a flow Hood…you can make them as simple as you want but you’ll sacrifice quality control, or you can go elaborate like I did (plans for the future) and large and it’s working great…36 blocks in 3 batches…only 3 blocks lost…all from our first batch…
Out of curiosity, what containers are you using to create your mushroom logs. They don’t look like the standard 5 gallon bucket.. Also, thanks for providing this info – very helpful indeed. I recently purchased the teardrop humidifier and greenhouse tent to finish the fruiting chamber which is currently controlled via an Arduino. Put up white plastic on most of the outside walls to help refract more light. My next task is to place waterproof LED lights inside the tent so that most everything is encased in the “mycohouse”. Cheers!
Looks like you have a great set-up going there! For the mushroom logs, I use poly tubing, 14″ inch lay flat diameter. But ya, the buckets are just standard 5 gallon Home Depot buckets.
I want to set up a greenhouse to start my experience with mushroom growing.
I’ve seen that some producers have two different chambers for the two different phases of the fungus life.
Should I create two different environments, if possible?
One for the growth of the mycelium: humid, “high” temperature and dark;
And another one for the fruiting phase: fresh aired, decrease temperature and a little light?
It really depends, you don’t necessarily need a separate room for incubation, but it will definitely help make the process more efficient and streamlined. For oysters though, typically you can just place them straight in the grow room for both processes. They do not need to be in the dark, and high temperature can often end up causing contamination rather than faster growth.
Hello Tony! Thanks for posting this it’s very informative and sparked great discussion! My question pertains to the outside of the greenhouse covering, I see mostly clear covers but in my home built design I was planning to use a opaque cover on the the outside and my question is if clear covering is the way to go for functional reasons or is just used more due to how it’s manufactured and doesn’t effect the overall process? Thank you for your time!
Hey guys I purchased all the stuff for the hobbyist grow setup but the pure enrichment humidifier does not turn on when the switch turns on the power for it; it has to be manually turned on through the button. What can I do to fix this? Thanks for the great website and articles!
Hey there! Not sure what might be going on, perhaps you got a defective unit? I have upgraded the “hobbiest set-up” humidifier to have a floating disc humidifier that blows in humid fresh air, works like a charm. Will update this post soon.
Tony, thanks so much for taking the time for all of these write ups. Between you and reading Paul stamets I have been able to successfully grow 4 different types of mushrooms!
I do have a question, I’m running a grow tent very similar to the 4tier mentioned here except it’s probably double the size. I’m using the crane teardrop humidifier you recommended with a humidity controller from inkbird that has a sensor to mount inside the chamber to kick on the humidifier when it drops below the desired setting. With my chamber being a lot bigger I’m wanting to be able to load it up with 20-25 oyster bags but I’m afraid the co2 levels may get too high, do you have any recommendations for blowing in more fresh air perhaps with a fan? Would this air need to be filtered and or exhausted out of the tent? Maybe Just incorporate a single exhaust fan? Any advice would be great! Thank you!
Hey Ryan! glad to hear the site has been useful! Yes, I would suggest building a “bucket humidifier” that blows in fresh and humid air. It’s basically just a 5 gallon bucket with a floating disc humidifier. You then attach a fan and pipe into the grow tent. Put this on a timer to dial in the exact levels of humidity you need. I use this at home for small grows and it works awesome. I will do a write up about it soon with pictures and perhaps add it to this post. Stay tuned!
Hi Tony can you give me some advice on how often to exchange the air inside the grow room if the room was only a 8 by 10 10 ft tall growing oyster mushrooms
I would use multiple air changes per hour, you likely need a small blower fan going constantly. You’ll be able to tell if your oysters aren’t getting enough fresh air.
Your tutorials are gold. I’m reading all the big-fat books (Stamets, etc.) I can consume, and it’s a daunting amount of (fascinating) information. But when I need a clear picture of how to apply this knowledge on any home-sized scale, I come to your site, and the “lights go on” for me. Thanks!
Hey Wynn! This is exactly why I do it- so happy that you like the site! All the best in your growing adventures!
Hey Tony. Do you think I need fan to take out air from my growing room if I’m going to use 4 tier greenhouse?
Depends on what you are growing. You may be able to get away with simply opening the doors and fanning often. Some Oysters need LOTS of fresh air.
I am a complete mushroom newbie. I am planning on using the 4 tier grow room setup with the PVC’d humidifier. I plan to use coffee grounds for my first batch of blue oyster mushrooms. If I purchased a 2.5 lb grain spawn, how much coffee should I use as substrate? Any suggestions on how much should each bag weigh?
Hey Amy! Just coffee by itself is not the best substrate, although it will probably work if you sterilize it properly. You will probably have better luck with hardwood sawdust. For the 2.5 lbs of spawn, you can make 4-10 5 lb blocks, depending on how fast you want it to colonize. 4 blocks is probably the better option, which will be a pretty high spawn ratio but will colonize fast and reduce chances of contamination.
How many heads does your pond fogger have? Do you think only one head could be enough with proper timer settings?
And I must say I really like your buisiness and website! Very informative and well done! 🙂
Thanks! Glad you like the site 🙂
The fogger I have has 5 heads, 3 heads would likely do but 1 head might get overworked… of course this highly depends on the size of the area that you are trying to humidify.
Just in the process of setting up my grow room, what sort of covering do you recommend? Thanks for all the great info.
Hey Andre! Poly sheeting or panda film should work great! If you want to spend a little more and setting up a permanent space, FRP is good- but expensive.
I love the advice given here, so easy to follow thank you
Would it be okay to just place an ultrasonic humidifier in the greenhouse? If so, would you recommend placing it on the highest or lowest tier?
Hey! Looking for a guide how to setup and build a whole room as fruiting room. Any ideas how to get hands on a guide? 🙂
After the initial fruiting of oyster mushrooms, how many additional fruitings will occur? I realize this number will vary based on conditions and species. Also is there any special steps involved to get more than 1 fruiting or is it more of a cut and come again type of thing. Thx
what is the production capacity for a 4 tier unit, and how long after ‘planting’ do you harvest.
Hi Tony, thanks for the great article. I’m planning to set up a greenhouse for a small farm of enokitake in jars. I’ll definitely install a humidifier but I’m more interested about controling the temperature inside the greenhouse. Any suggestions?
Hey, I am trying to set up a Mushroom Growing tent. Wanted to know how can I regulate the temperature in the tent? If possible the cheapest way possible. Planning to set up a hydroponic tent of 20 feet by 10 feet.