Winter Update: Lush hydroponic growth and flowers on the pepper plants!

Lots of things are working well. Updates for the Greenhouse, the Rapberry Pi and the Hydroponic systems.

Greenhouse:
Greenhouse is keeping the temperature higher than the normal air. The raspberry pi has been consistently reporting higher temperatures on the inside of the greenhouse compared to the outside. It is keeping the temperature at the high 80s in the middle of the day and mid 70s at night.

Check the twitter account to see what it is currently! Be sure to retweet or favorite a tweet! It is always helpful to me to know that people out there are seeing the Pi on twitter. (@rpiph1)

The plants have been growing very well in the warm temperatures. After about 3 months from planting (see the previous blog post) the plants were very lush and dense. Four months after to have to trim back the plants so that they don't hit the light. Additionally I have my first flowers on the pepper plants opening up and lots of plants developing flower buds!

 

The best plants for hydroponics:

The bell peppers and hot peppers are growing really well.

The basil is doing really well. 

The tomato plants grow but I think I need a bigger space for them to actually fruit. 

Green onions and garlic grow well. 

Pepper plant flowering in the hydroponic greenhouse: 

 

The Raspberry Pi:

The raspberry pi has been tweeting uninterrupted for months using the code I published in the October 18th, 2015 blog post. (the one right before this one) The temperature sensors have been accurate and reliable for months. Nothing new to report here. 

Hydroponic Systems:

The water pump (running 24/7), box of hydroton grow rocks, tubing, and coarse screen for filtering is all working well. No leaks to report. I add more water to the reservoir every few weeks. 

Raspberry Pi Powered Hydroponics Version 2.0!

Intro

This is a big update and nearly everything has changed in some way. I have made an effort to simplify both the hydroponics parts and the Raspberry Pi computing parts to make things a little more robust than they had been. First I will discuss the hydroponic changes, what they are and why I made them, then get into the new Raspberry Pi changes and why I made them.

Hydroponics

The biggest change I made was to get ride of my three trough system for a simpler one large box system. The three troughs were interesting because i could swap the small cups in and out whenever I wanted but it also meant I have three water hoses and three options for leaks to happen. With a simple large box the gardening is more like you have a very small plot of land and have to pick and choose regions of your box to plant certain seeds. It also means that I only have one inlet tube and one outlet tube, which should give less opportunities for leaks to spring up. I am using the same water pump and water reservoir as before, just the plumbing has changed. 

I made the box our of a wooden palette then lined it with about 6 layers of black plastic trash bags. As you can see on the left side is the input spigot of water and the output is on the underside of the box on the right side (not shown). Planted the seeds a few weeks ago and already starting to see some sprouts!

Computing 

The major changes of this update have come on the computing side of the project. I am now using a Raspberry Pi 2, but that is largely inconsequential to the project but its worth mentioning. 

Previous posts have discussed how the addition of data to the mySQL data base every hour was hard on the SD cards and would cause them to be corrupted frequently.  In the past, to fix this, I had attached a small disk drive to the Pi so that all the reading and writing of the mySQL database and the collection of graphs that I was rendering would have some place more stable to sit. With this update I have decided that all of that was too complicated, and while the graphs were pretty cool I didn't look at them THAT often to really justify continuing with them. So I have done away with the disk drive, the USB hub to power it, the mySQL database, and the php grapher program.

In place of this I have added a second temperature sensor that I wired to the inside of the greenhouse so that I can see if the greenhouse is actually helping (spoiler alert: it is). Since the TMP36 (cheap temperature sensor) relies on voltage to determine the temperature, it was important that the control temperature sensor that sits outside the greenhouse on my window sil have the same length wiring as the one that runs inside. The increase in resistance associated with the longer wires was effecting the readings so I just made them the same length so I didn't have to worry about adjusting one or the other. I also still have the same basic light sensor I used before, except this time I convert its output to a % value which is more meaningful than some 8bit value it spits out. In my original testing I showed that you can change the range of these values based on how much light you are likely to detect with changing the resistor in its circuit. I determined that using my current resistor was a good range of light levels and 100% would be really really bright and 10% is nearly lights off. I am also still using the MCP3008 analog-to-digital convertor to convert the analog signals that the temperature and light sensors give into digital values the Pi can interoperate. 

Here is a cartoon I made of the Pi's wiring: 

I used this really great program called Fritzing to make this cartoon showing all the wiring of my Pi and the sensors! Its a free program (donations gladly accepted) http://fritzing.org/home/ . Check it out if you are interested.

The twitter code is largely the same except this time I am tweeting about the difference in the greenhouse temperature compared to the apartment air temperature. (and light levels and the Pi's core temperature) The temperature sensors are not super precise so if they are within two degrees of each other I claim the inside greenhouse compared to outside greenhouse are roughly the same. Its only if the difference if greater than 2 degrees (in either direction) that I claim one is warmer than the other. As we descend into winter I made add a line to the tweet about how big that difference is to really show off how well the greenhouse is doing but its fine for now.

All these changes have made the Pi a lot simpler, and it runs a program every hour and tweets its information. There is no storing of data or graphs so nothing is "building up" on the Pi which I hope will lead to longer term stability. Because the code is much simpler (and doesn't include a PHP graphing step) it runs MUCH quicker than the old code did. The code also includes the very small bit of logic surrounding the two temperature readings and how that changes what the Pi tweets. And as before I can't show you the Pi's twitter credentials for obvious reasons, but f you use this code that it where you would include your own credentials. (lines 122-125) Feel free to use the code however you please just remember to cite it!

And as always, follow the Pi on twitter so that t can spam you every hour! @rpiph1 12,200 tweets and growing!

Here is the simplified code: 

Plants plants everywhere. Biweekly pruning becomes a necessity.

It is still very much winter here in Chicago and the plants are acting like it is mid summer! Except for flowering, the peppers hint at flowers sometimes but haven't had some open yet. I have to prune two large handfuls of plant material off the tops of them plants every few weeks to keep them from smashing up against the sides of the greenhouse too badly.

This is what the greenhouse looks like today. (March 23) My previous two posts show pictures from early and late January.

My plant biomass is very high and quite crowded. Hurts me to prune them back so heavily since it wasn't so long ago that I was struggling to get them going. As you can see form the middle picture (and all of them really) it is about time for a prune. Especially the one site that faces my window gets denser. I will try to pull some of these plants toward the other side and into the wire trellis. 

Now the only part I am missing is some flowers so I can get some fruit going! Wondering if the temperature needs to be higher for that. We will see what happens as it gets warmer outside. But the plant biomass and health is excellent so I am not worried! 

Hydroponic tomatoes, peppers, and basil take over!

From January to march I have had explosive growth in my tomato, pepper, and basil plants in the green house. A few months with the LED lights made a huge difference in the growth. So much so that I have had to make some changes to the greenhouse.  But first look at this! This is only three weeks after the picture in the previous post was taken.

Some of the updates:

Water tubes clogging and root issues:

Once you get a significant amount of roots they start to find their way down the water tubes and if you get enough roots this can really start to hamper the flow of water. Worse case scenario, the outlet/return water lines get clogged, water cannot return to the reservoir, over flows and dumps water all over the floor, and the pump runs dry. It has happened. It is okay to trim your roots back, the plants have no problem growing more as long as you don't go too crazy. 

Debris in the water reservoir clogging the pump:

Pretty common problem. There is a brown silt light sludge that come out of the plants, looks and smells like a river bed, seems natural so I am not worried. I did encase my pump in some screen (for screen doors or windows) it was only a few bucks for way too much of it from my hardware store. I also made a little basket of screen that my water return lines strain their water into before it dumps into the reservoir. This has really cut down on any larger organic material chunks getting into the pump and clogging in. Now what I have is a fine silt like material that settles to the bottom of my reservoir tub and easily washes out when I clean the tub. 

The LED light strip:

The plants were obviously getting to big for their original hanging lights so I used velcro to attach the light strip to the top of the green house. 

Trellising:

The tomatoes, and to some extent the basil, really benefit from some structure to lean and grow on. To address this I screwed 4 eye hooks about 3/4 the way up on the four corners of the inside of the greenhouse and used green floral wire to weave a square wire grid. It is hard to get a picture since the wire is thin and green, but hopefully you can see what I have done. Then I carefully pulled up some of the plants and laid them on top of the wire. 

I also snapped this picture in the middle of the day one day. Just proves that my greenhouse is actually working as a greenhouse and keeping moisture in! Very cool. 

Hydroponic growing in the dead of winter! LED light strip saves the day.

My seedlings were not doing very well and I assumed it was due to the lack of a strong light source. (they were thin and leggy) I get good sun though my south facing window but its is the middle of winter (when the picture was taken) and the hours of sun where low. I decided to add in a LED light strip and have had a lot of success with that.

The LED light strip: http://www.adafruit.com/products/306

RGB 32 LED strip with programmable colors in any all the colors of the rainbow. From various sources it is known that red and blue light work the best. Simple science, plants are greenish yellow to our eye meaning they reflect those colors and absorb the other in the visible spectrum, namely blue and red.

I had to add a 5V additional power source to get the maximum light out of stripe since the pi does not supply enough power on its own.  There is plenty of documentation out there and tutorials with this strip if you decide to use it for your project. It comes with a demo program that seriously runs for nearly 10 minutes with all the flashing, waves, pulses, colors etc that it is capable of doing. Seems a little overkill now to just ask it to run on its blue and red LEDs.

As soon as I put the light in my plants responded very well, the lights are on for about 16 hours a day. This picture was taken on January 2nd in the middle of a Chicago winter and my plants are happily growing! I consider this a hydroponic success. This was exactly the point, to continue to grow plants in the dead of winter!

You can also see here that I zip tied a short piece of wood to the light strip so that it would lay flat. Can also see the purple hue of the red/blue LEDs.

18 days after planting and a small water leak

It has been 18 days since I planted all the seeds and nearly all the seeds have sprouted. The watermelon and tomatoes sprouted quickly and as of now only the anise and the peppermint do not yet have visible sprouts. The chives, watermelon, peppers and tomatoes are doing the best so far!

Also had a few small water leaks out of one of the drainage tubing nipple connections. I applied more silicone sealant to solve the problem.

New picture for the Twitter account!

Don't forget to follow the Pi Farm on twitter if you want to be spammed every hour with the latest temperature, humidity, and light level information.