Plants not very happy in Arduino climate controlled terrarium?

Recommended Posts

Hello! I am having trouble keeping my plants happy, and would like to ask you for your thoughts!

I live in Arizona USA, where it is very hot outside. I have constructed a Terrarium for indoor use and programmed an Arduino motherboard to control the light, humidity, and sprinklers.

Arduino: I am using an Arduino R3 motherboard. ( in combination with this relay to help control the 12v devices with a 5v signal: ( If anybody is interested in my code I would be happy to share.

Terrarium Climate: I chose most of my climate parameters based on the nepenthes plants I wanted to try growing. I have gathered the humidity and temp growing conditions from the books "Growing Carnivorous Plants" by Barry A. Rice and some from "The Savage Garden" by Peter D'Amato. I will include a list of the species I am growing below.

Light: I am using a standard fluorescent circline light fixture I have suspended over one side of the terrarium with mirrors underneath. I have been experimenting with plant location directly under the light or slightly farther away to avoid burning. The light is programmed with the arduino to provide the accurate number of daylight hours per month based on daylight hours in Georgia USA (random east-coast city for me really). I chose an east coast city only because I think most of these plants are native to the east coast. Perhaps I should change this?

Humidity: Even though the terrarium is not airtight, if I let it go with no intervention the humidity rises rather quickly. With all those water trays, the humidity will keep going up. The humidity sensor is set to turn on a computer fan built into the custom lid to keep the humidity at 70%, but the sensor is a cheap one with poor resolution. I have managed to keep the humidity between 65-75% for the most part. The arduino sensor I use is here (http://www.trossenro...ity-sensor.aspx). I would like to upgrade this sensor as soon as I can. It appears to be precise but inaccurate. I have already purchased two. Because it is precise, I have simply compared its output to a sensor I bought at a local hardware store and hardcoded the difference. I can’t say I recommend that sensor very highly.

Temp: The ambient temperature is uncontrolled and remains close to the ambient temperature of my house, but the light itself does heat up the terrarium some. It is usually 83 F with fluctuates between 75 F at night and peaks at 90 F during the day. The lid of the terrarium is not air tight, and the computer fan (to lower humidity) allows for very little airflow, but airflow does occur.

Sprinklers: The sprinklers are set to spray a short 5 second burst of water twice daily, once in the morning and once in the evening. I use distilled water only sprayed with two standard irrigation mister heads. The water is pumped with this pump (http://www.trossenro...ump-medium.aspx).

Watering: I have not yet programmed the irrigation for watering so I am doing this manually. I water only with distilled water. I have suspended my two nepenthes species over a water tray and water every two days until water drips through to the bottom of the tray. All other plants are watered by keeping the pot in 1-2 cm of distilled water. I allow the base of the water tray to remain dry for 1-2 days before refilling the tray. I have noticed that this method does not result in the soil drying out though. Perhaps I should be allowing the soil to dry out?

Feeding: I have been releasing flightless fruit flies into the terrarium every couple of weeks. It is very hard to keep flies alive in Arizona summers.

Species: Here is a list of the species I am growing. The format is (Species: Humidity, Temp).


Drosera capensis: High, 50-95 F

Drosera spatulata - Spoon Leaf Sundew: ?, ?


Dente Flytrap (?): High, 68-95 F

Dionaea muscipula: ?, ?

Dragons Tongue: ?, ?

Trumpet Plants

Serracenia rubra rubra - "Sweet Pitcher Plant": 40-90%, 55-104 F

Serracenia purpurea - "Purple Pitcher Plant": 40-90%, 55-104 F (?)

Pitcher Plant

Nepenthes burkei x singalana (Highland): 60-80%, 77-86 F

Nepenthes maxima (Highland) - "Wavy Leaf": 60-80%, 77-86 F


?, ?, ?

Pictures: Sorry I do not know how to put pictures into this post! I have included some flickr links though.

Here is a picture of the whole terrarium. You can see the fan in the lid at the upper left of the pic.

Here is a picture of the plants directly under the light. I have cut out a little plastic mesh to cover the exposed water in the tray. This was because the wingless flies I was feeding them were finding the nearest water and promptly drowning. These allow them a route over the water and up to the plant. Works very well. You can see Nepenthes in the upper left, trumpet plants upper right. Sundews in the middle. A very sick looking flytrap in the lower left. I bought it because I thought I could save it. I think it is a dragon’s tongue but I an unsure, as it has red coloration inside the traps. In the lower right you can see some type of butterwort that was given to me, I do not know its species?

Here is a picture of the plants positioned a little to the right of the lamp, Some rubra-rubra pitchers in the upper right, and the flytraps in the lower right. I do not know what species the large flytrap is in the very lower right, but it is not looking well. It has gigantic traps.

Side view of the Terrarium, you can see the two sprinklers on each corner held on with hot glue, and the temp/humidity sensor suspended in the middle. The misters do not mist the sensor with this configuration.

The R3 Arduino.

The relay is inside the blue box and covered with outlet covers.

Any ideas, comments, or suggestions on how to make my plants happier would be greatly appreciated! Any identification of those unknown plants would be nice too. Thanks very much!

Edited by cpukMacLean
  • Like 1
Link to comment
Share on other sites

I would take the lid off put some gravel and water in the bottom of the tank and open the blinds, that should be a better environment for most of the plants in there. Maybe save all the fancy gear for the Nepenthes spp in a separate tank

Link to comment
Share on other sites

  • 1 month later...

Richard thank you very much for your suggestion! I raised the plants up after your suggestion and am posting a follow up! All of them are now 6-8 inches away from the light and they started taking off like rockets! Flowers and new growth, lots of new pitchers! They are so much happier, as am I!

I do appreciate your response Mantrid! I toyed with your idea, but the terrarium is not water-tight. This one is a reptile enclosure hand-me-down terrarium. It is surprising how hard it is to keep the humidity down with only the water trays in there, so adding more water to the bottom of the tank would not really help to raise it more. I did add some nice garden rocks to the tank though, and it really adds a great touch to the feel of the terrarium! Thanks!

The arduino does a nice job, but I fear the sensor is really quite low quality. I plan on testing some new sensors soon. :) If anybody has any arduino temperature/humidity sensor advice I would love to hear it! I will post some pictures of the new terrarium soon.

Thanks again!

Link to comment
Share on other sites

I don't have experience with arduino but I have been using humidity sensors from Sensirion, the SHTxx series. They are expensive but good. And lately I found another sensor which does well even outside in very cold weather: HYT-221. Good luck.

Link to comment
Share on other sites

I would check out SunBlaster T5 lamps. SunBlaster have recently introduced clip on parabolic reflectors and they look the business. I am using SunBlaster lamps to grow Venus Flytrap seeds in a propagator. I have got the reflectors but they do not fit the older design of fitting. If you do a bit of research to find the lamps you will see that they have clips that allow the lamps to be suspended and that is one way of adjusting the height above the plants.

Link to comment
Share on other sites


I am interested to see your terrarium.

I have just experimented with a spray nozzle removed from an atomiser spray - a bit like the top of a perfume bottle spray - with a peristaltic pump (ebay). It worked perfectly. I would think that using a y piece a spray head could be mounted in each end of a terrarium to give good coverage.

Just thought you might be interested.

Edited by Peabody
Link to comment
Share on other sites

OK So I've taken some new pictures. Yesterday I purchased a new light fixture for the top of the terrarium, and I plan to reorganize the whole setup today to include the second light. I wanted to post these pictures first to show the current status of the plant growth.

Overview Pic:

Closeup 1:

Closeup 2:

@Patmil: AH wow thanks! I've been using a $6.00 DHT11 from Trossen Robotics and it is really a strange device. It is 32% away from the second home-depot LCD sensor I use as a baseline. And if the relative humidity drops below 60% the readings suddenly drop to about 30%. Very strange. I will have to try the SHTxx Series next!

@Peabody: I checked out the sunblaster products and I have to say I am impressed. In those pictures above you can see one circline light fixutre, but just yesterday I bought another one. The very basic circline light fixtures with no light diffusion cover cost $20 from Lowes. Here is a picture but it is much to expensive from ebay: and the T9 lights themselves were $15 for the outside ring and $10 for the inside ring. The spectrum is 6500k (from Home Depot) and total of 4960 lumens. Total cost of lighting (with taxes): ~$100. The comparable sunblaster light fixtures seem to start around $150? Although I'm having trouble finding the exact numbers. The prices seem to vary quite a bit. The strips themselves are very nice though, and I will seriously consider upgrading to a larger set of sunblaster lamps in the future. And thanks for the info about the spray nozzle. The little pump I got from Trossen Robotics is extremely powerful and the current coverage is probably too good as the light fixtures get quite wet after a rainfall haha. I will try out that irrigation heads instead to avoid wetting the lights. Thanks!

@snowwy: Tinfoil works!? Thats an amazing low cost alternative! I have some mirrors to use, but they are the square ones and I cannot make them fit just right. Is there a brand or type of tinfoil that works better than others?

Edited by cpukMacLean
Link to comment
Share on other sites

  • 2 weeks later...

Update 10/21/2013

Sensor Problems: The DHT11 sensor I have hooked up is now giving completely nonsense readings. I have tried (and failed) to upgrade the library files to a new set. If anybody knows how to do this successfully with this sensor I would appreciate any input. As a stop-gap until I have enough money to purchase a proper SHTxx sensor, I have decided to take a new approach to keep the humidity down. I simply turn on my fans every 7 minutes for a full minute. This interval took some trial-and-error to arrive at, but it now balances the relative humidity between 68 and 78 pretty reliably. I am surprised how predictable the rise in humidity is. The issue I am having now is that the entire program crashes at some point in the night, every night. If there are any programmers out there who are familiar with arduino code, I would appreciate any input. I'll send my code your way! In the mean time I'll keep tweaking it.

Light Upgrade: When I started this terrarium many years ago, I originally bought one light fixture and two circline lights from Lowes without fully understanding what "K" values are. It did not help that Lowes only has one circline light bulb to choose and, from the comparisons I have made recently, it appears as though I bought a 3000K bulb all those years ago. My success growing plants with that much of a red-shift surprises me. When I decided to invest in a new bulb fixture I preformed more research and decided on 6500K bulbs this time. I have intermixed them in the light fixtures. Each fixture holds two bulbs and in one the outer bulb on one is 6500k, inner is 3000k, and vice versa on the other. Only time will tell if this arrangement will be beneficial to the plants but short term findings appear to be quite positive. I made this decision mainly to save money but also because many of these plants use different wavelengths of light for different reasons. I read usually red-shift bulbs aid in flowering, while more daylight full spectrum bulbs aid in plant growth. I figure having both will be a great upgrade from what I had before.

Mirror Upgrades: I have lined the non-viewing sides of the terrarium first with tinfoil and then mirrors. Honestly the crinkly tinfoil look is not very pleasing on the eye at all. I had the spare mirror panels from Home Depot and those look much better. There is also tinfoil taped to the lid of the terrarium enclosure to help reflect light down. It appears much brighter than before.

Plant Upgrades. To the terrarium I have added two new carnivorous plants. One unknown butterwort species with long narrow stiff leaves, and one new Nepenthes of unknown species with quite round broad leaves. In the "Right View" picture below you can also see a mini-orchid species I added to the enclosure with beautiful blue and white flowers. Breathtaking plant. Visited a great orchid-festival at Gublers Orchids in California ( and bought both the mini orchid and the new Nepenthes plant there. The orchid farm is /way/ out in the desert, just north of Banning California (windmills... so many windmills!) but it was well worth the drive and I had a great time at the festival. They also sell carnivorous plants, which is why we chose to drive out there.

Flytrap Problems: I have never been able to keep flytraps growing to my satisfaction. I have not killed them either, but never made them look super happy. I have changed from a swamp-watering method (sitting in a tray with water in it) to a draining method in which I let the water drain through the pots completely. I have also moved two flytraps out of the terrarium in hopes they may thrive in a windowsill instead. One in the windowsill I have covered with a hurricaine glass to raise the humidity a bit. We will see if that helps it.

Thanks again for everybody's help. Here are the latest pictures:


Left View:

Middle View:

Right View:

Edited by cpukMacLean
Link to comment
Share on other sites

Hi cpukMaclean.

I am controlling my greenhouse (or trying to) using an Anduino Uno. It is only a small greenhouse and more just for fun since I like playing about with electronics etc. I have a LCD connected to display the temperature and humidity read in with a DHT22 temperature/humidity sensor. I also control a large pc fan really just to take the peak off the temperature on hot days - few and far between here. There is also an ultrasonic humidifier which is positioned to blow humidity over the plants that need it the most on dry days. The Uno is fitted with a shield to provide a real time clock and sd card which I use to record the temperature and humidity - hardly necessary but fun anyway! I wanted to be able to control and monitor over wi-fi but didn't want to open up my network so I have run a cable from the greenhouse to the garage and connected the comms to a raspberry pi which has a wi-fi link so I can access this over network. Oh, just remembered, I also have a 12v pump to automatically water the plants from the Uno as well!

I should say that I also grow carnivorous plants!!!!! Maybe this is in the wrong forum?

This is also very much work in progress.....

Would be interested in a software swap. I am on my second sensor but I did accidentally flood the first one. Seems to be reasonably accurate.


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.