Picture of Mushroom Environment Control - Arduino Powered
This is my first Arduino project aimed at helping me with my other hobby which is growing oyster and shiitake mushrooms indoors.
In a nutshell, the controller takes in two temperature readings, 1 Humidity reading and 1 Co2 reading and triggers a set of four relays connected to mains power.
Intended to be connected to the mains are two heating pads, a sonic humidifier and an air pump (although the choice isn't limited to these of course).

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Step 1: Items

Here is the list of items I used for the project.

-LCD Keypad shield.
- 7-12 volt power supply.
- USB cable (socket that connects to USB on Arduino).
-Box To house the whole thing.
- 4x solid state 5v- 240v relays.
- Mains Power board with four sockets. 
- Wires.
- Jiffy box to house inline socket/screws to connect Sensors.

-Thermistors 10k   x2
       -Resistor 10k  x2
-HS1100 humidity reader
       - 555 timer (cmos type)
       - resistors: 576k, 49.9k, 1k and 909k
       - Veraboard/breadboard
      - Jiffy Box
      - Digital divide by ten Chip
-MG811 C02 sensor (I got a breakout board with op-amp amplifier built in. You can make it yourself, it is a high precision op amp set up as non-inverting with gain around 10).
       - Jiffy Box

- 2 x heating pads
- Sonic Humidifier
       - Aquarium Tubing
       - Air Pump (aquarium)
       - Plastic lunchbox (airtight) 
       - HEPA Filter for Vacuum cleaner.
       - Plastic tub 
- Aquarium Air pump
      - Aquarium Tubing
     - Plastic Lunchbox (airtight)
     - HEPA Filter for Vacuum cleaner

- Hot Glue gun
- Soldering Iron
- Screwdrivers
- Multimeter
- Drill
- Home brew larger.

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What is a digital divide by ten chip. Having issues finding this and would like to complete this project. Awesome job by the way. But please tell me what chip to order

anthony_p1234 (author)  DustinSievers436 months ago
Hey Mate,

I've done a revision on this, I use RHT03 for temperature and humidity sensing:
It's digital so a lot more accurate, and less fuss.
Also rather than using a C02 sensor I'm just scheduling airflow (i.e. fan on for one minute ever 10 minutes....but it depends on your fans airflow).
If you want the code for this, let me know and I can supply.



I am replicating this project for a wide format production print room humidification system. Would you please provide the updated code for the RHT03? Thank you.

Hi Anthony, would you mind providing us with your code? it would be of great help, and if you can your schematics. Regards.

Akin Yildiz4 months ago

good stuff..!

HeliosV29 months ago

How did you deal with the 'bounce' on the SSR's due to low power consumption? I'm finding I get intermittent activation when the relay is supposed to be off. Very irritating!

ahorn81 year ago
Nice project. I'm working on similar using a DHT-22 for Temperature and Humidity. Sweet setup with the CO2 sensor N all. I may put some ferns in the grow room just for now. Thanks for posting.
Hello Anthony sir,
Very nice project. Keep up. Can you please help me too?
Based on this instructable can you please modify the code to use with sensirion sensor - sht75 to control relays for humidifier and heater instead of dht-22 sensor? Thank you.
AlanFFM2 years ago
Great project! I'm trying to rebuild it but have this programming problem. I'm using the arduino uno which uses the liquid crystal library. For some reason I cant get the code to work at all and my knowledge in programming is sub par. Any tips or advice would help a ton. this is a project I'm very interested in.
thanks :)
jbark3 years ago
Hi Anthony,

I'm new to electronic. I got my self cd4017 for the divider, can you please tell me where you the output from 555 goes to? Or how do I know which one divides. This one is tricky to follow.
By the way this is my very first electronic that's not a kit from Jaycar. I'm almost there with it but this one has got me stuck.

So I followed your instruction.


anthony_p1234 (author)  jbark3 years ago
Hi Jbark,

Sorry, I didn't put much detail in about that. But basically it's something like this:
555 Timer --> pin 14 of cd4017. Then output of cd4017 pin 11 to arduino. Ground pin 8, 13 and 5.

Sorry... Ground are pins 8, 13 and 15. Thanks
Thanks Mate
Co2 too low??? You said "This system of air filtration is also used for the air supply when the co2 gets too low". Dont you want the co2 to be as low as possible?
anthony_p1234 (author)  thebestofall0073 years ago
Yes, it's meant to read "CO2 gets too high". The program switches the relay on when the CO2 level goes over a certain threshold. I just wrote the wrong thing and my editor didn't pick it up before it went to print.
bsnob3 years ago
i saw someone make a similar device a long time ago , but no co2 sensor though and they connected it to the lpt1 port of a pc to control it , but it was used for mushrooms , i wish i could find the site where i saw it he had a basic software he wrote for it and everything and he was even selling kits or providing exact part lists with item # and where to get them ,i was interested in makingg one of these for a greenhouse ,but with a pc control or interface and a data logger, anyone know where i could fing plans for something like that?i thought i sa it on the shroomery but i forget and a search there turned up nothing
Asameea3 years ago
Hi Anthony, I want to know the amount you paid for CO2 with singal conditioning as shown in the diagram.
As you told about that website, i have checked the product, its cost is around $35, but i want to know exact amount i should pay for delivery to India.
Hence i am asking you to tell me the amount you paid for the same.
Thank you.
anthony_p1234 (author)  Asameea3 years ago
I think the shipping was roughly around the same price of the item (35$).
It is a bit pricey. You can always skip this equipment and just set up the relay to turn on to drive a pump to exchange air for a specific amount of time every hour or so. (or use a timer :) )
I have had good results with this.

Also, the Co2 sensor is the most sensitive being logarithmic and is difficult to calibrate.

This is up to you though.


tsenarathna3 years ago
Hi Anthony,

What sort of output data did you end up getting with the Parralax sensors? Great work btw!
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anthony_p1234 (author)  rocketsurgery4 years ago
What you're doing sounds great, mushrooms are excellent in the way that they can transform wastes into fertile soils etc. ... and good for eating too! I never knew projects like yours existed, awesome!
Hey again... If you are interested in what we have been doing with oysters in Afghanistan, I have recently published a couple of instructables...

How to Grow Oyster Mushrooms Low Tech and
How to Grow Oyster Mushroom Spawn Low Tech

I have just constructed a hepa filter laminar air workstation to help with producing spawn... might like to try your instructable out with regard to our test growing room... Thanks again for sharing...
Currently we are growing them in straw (which then, after harvesting, gets given to their animals)... the great thing is that they don't need lots of land and the locals love them (other types grow naturally in spring and in the mountains)... we need to get them reproducing the spawn to complete the cycle... we'll see how that goes... thanks again for your 'ible!

Paghman Mushrooms.jpg
ratheeshbr3 years ago
Can you please tell me from where did you got this CO2 Sensor in India?
anthony_p1234 (author)  ratheeshbr3 years ago
Hi Ratheeshbr,

It was the MG811 co2 sensor, I got the sensor in kit with omp amps from parallax on the web. Google for parallax co2 sensor gets you there.

rt614 years ago
I would like to learn how to grow oyster and shiitake mushrooms. Where should I start? Thanks!
wifigod rt614 years ago
Raziel7 wifigod4 years ago
DVDs and books are good starting points for learning about growing mushrooms, but will not teach you how to grow them well. Most of the material is somewhat outdated.

New methods conceived by mycologists and growers can be found at

Search the forums for all the knowledge you will ever need, plus it is free.
anthony_p1234 (author)  wifigod4 years ago
(removed by author or community request)
It'd also recommend it. It's very highly informative and contains a lot of species specific information that'd be difficult to work out for yourself. I'm loving this project. I started a similar project about three years back that used almost exactly the same methods. The only variance really is that I used a Wine Cooler as the case to battle blistering California temperatures and a Sensiron SHT11 combined temp/humidity sensor. Except my Arduino BT (Sparkfun accidently upgraded my order) melted down and I've been working on rebuilding another board from scratch. T_T; It's not going well~ One question though. Why the choice of Thermocouples over serial interface temperature sensors? I believe the prices are comparable, and serial interface is such a breeze to work with.
anthony_p1234 (author)  Kitoru4 years ago
At the time I was making the project It didn't occur to me to use serial (is it i2c?) and didn't know arduino was able to use it. The more I find out about the Arduino the better it gets :).
just steal it from ED2K ed2k://|file|%5BPsilocybin%5DGrowing%20Gourmet%20and%20Medicinal%20Mushrooms-Paul%20Stamets-2000-1580081754.CV.pdf|36908319|D7C4B3A02C96D1823E012B22315E98CE|/
joystik rt614 years ago
Youtube is your friend. Also, check the torrent sites for "Growing Mushrooms" DVD.
Very cool use of the arduio. It's a great start for your first time coding in "C". GuruSantiago Checkout my arduino projects here: And follow me on twitter @ElectronicsFun
ladrua4 years ago
I was thinking the same thing. I am building a similar project, and base my relay sircuits from this guide
wifigod4 years ago
I'm very excited to see somebody working on a very similar project as me! :-D I do have one question, where did you buy the MG811 that came with the op amp board? I too made the mistake of buying just the sensor and couldn't get it to work. (I'm NOT an electronics person, but I'm trying to learn!) Thanks!
anthony_p1234 (author)  wifigod4 years ago
I got the MG811 with op amp from parallax a company I found through the internet. Good luck with your project! :)
Very nice project. I am creating a home HVAC data logger. As a side note the documentation on the mg811 sensor is very poor. I have the sensor working, I am concerned about the temperature. Do you keep the mg811 heater on constantly, or preheat it before polling? If so is the sensor hot to the touch?
anthony_p1234 (author)  ksgeek4 years ago
For my project I keep the heater on all the time, although the MG811+op-amp board had a pin that you could use to switch the heater on/off. I guess it may affect the shelf life of the sensor if it is on less frequently. The sensor is more warm than hot, although when I did put in the wrong voltage it did get too hot to touch (it didn't destroy the MG811 though!). To answer your question I did find that the sensor took a while before the reading became constant and didn't keep dropping, it was about 5 min.
twhaley4 years ago
That's, i'm doing it!
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