A Single-Watt Hydroponic Lighting System

Hydroponic systems are an increasingly popular way to grow plants indoors using a minimum of resources. Even some commercial farming operations are coming online using hydroponic growing techniques, as these methods consume much less water, land area, and other resources than traditional agricultural methods. The downside is that the required lighting systems often take an incredible amount of energy. That’s why [ColdDayApril] set up a challenge to grow a plant hydroponically using no more than a single watt.

The system is set up to grow a single pepper plant in what is known as a deep-water culture, where the plant is suspended in a nutrient solution which has everything it needs to grow. The lightning system is based around the Samsung LM301B which comes close to the physical limits for converting electricity into white light and can manage around 220 lumens. A special power supply is needed for these low-power diodes, and the light is efficiently directed towards the plant using a purpose-built reflective housing. By placing this assembly very close to the plant and adjusting it as it grows, [ColdDayApril] was able to take the pepper plant from seed to flowering in 92 days.

It’s worth noting that the rest of the system uses a little bit of energy too. A two watt fan helps circulate some air in the hydroponic enclosure, and deep-water systems usually require an air pump to oxygenate the water which uses another two watts. This is still an impressive accomplishment as most hobbyist builds use lighting systems rated in the hundreds of watts and use orders of magnitude more energy. But, if you’re willing to add some fish into the system you can mitigate some of the energy requirements needed for managing the water system even further.

close-up image of a philodendron houseplant with electrodes attached, connected to a robot arm holding a machete

(Mostly) Harmless Houseplant Wields Machete

In a straight fight between a houseplant and a human, you might expect the plant to be at a significant disadvantage. So [David Bowen] has decided to even the odds a little by arming this philodendron with a robot arm and a machete.

The build is a little short on details but, from the video, it appears that adhesive electrodes have been attached to the leaves of the recently-empowered plant and connected directly to analog inputs of an Arduino Uno.  From there, the text tells us that the signals are mapped to movements of the industrial robot arm that holds the blade.

It’s not clear if the choice of plant is significant, but an unarmed philodendron appears to be otherwise largely innocuous, unless you happen to be a hungry rodent. We hope that there is also a means of disconnecting the power remotely, else this art installation could defend itself indefinitely! (or until it gets thirsty, at least.) We at Hackaday welcome our new leafy overlords.

We have covered the capabilities of plants before, and they can represent a rich seam of research for the home hacker.  They can tell you when they’re thirsty, but can they bend light to their will?  We even held a Plant Communication Hack Chat in 2021.

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All-In-One Automated Plant Care

Caring for a few plants, or even an entire farm, can be quite a rewarding experience. Watching something grow under and then (optionally) produce food is a great hobby or career, but it can end up being complicated. Thanks to modern technology we can get a considerable amount of help growing plants, even if it’s just one plant in a single pot.

Plant Bot from [YJ] takes what would normally be a wide array of sensors and controllers and combines them all into a single device. To start, there is a moisture sensor integrated into the housing so that when the entire device is placed in soil it’s instantly ready to gather moisture data. Plant Bot also has the capability to control LED lighting if the plant is indoors.  It can control the water supply to the plant, and it can also communicate information over WiFi or Bluetooth.

The entire build is based around an ESP32 which is integrated into the PCB along with all of the other sensors and components needed to monitor a single plant. Plant Bot is an excellent all-in-one solution for caring for a plant automatically. If you need to take care of more than one at a time take a look at this fully automated hydroponic mini-farm.

Green Roofs Could Help Improve Solar Panel Efficiency

There’s been a movement in architecture over the past couple of decades to help tie together large urban developments with plant life and greenery. We’ve seen a few buildings, and hundreds more renders, of tall skyscrapers and large buildings covered in vegetation.

The aesthetic is often a beautiful one, but the idea is done as much for its tangible benefits as for the sheer visual glory. Naturally, there’s the obvious boost from plants converting carbon dioxide into delicious, life-giving oxygen. However, greenery on the roofs of buildings could also help improve the output of solar installations, according to a recent study from Sydney, Australia.

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Occam’s Razor: Gardening Edition

While the impulse to solving problems in complex systems is often to grab a microcontroller and some sensors to automate the problem away, interfacing with the real world is often a lot more difficult than it appears. Measuring soil moisture, for example, seems like it would be an easy way of ensuring plants get the proper amount of water, but soil is a challenging environment for electronics and this solution often causes more problems than it solves. [Kevin] noticed this problem with soil moisture sensors and set about solving this problem with a much simpler, though indirect, method of monitoring his plants electronically.

Rather than relying on soil conductivity for testing soil moisture levels, he has developed an alternate method of determining if the plants need to be watered simply by continuously weighing them. The hypothesis that he had was that a plant that needs water will weigh less as the available water respirates out of the plant or evaporates from the soil. This means that using a reliable sensor like a load cell to measure weight rather than an unreliable one like a soil moisture sensor will result in more reliable data he can use to automate his plants’ watering.

[Kevin]’s build is based around an ESP32 and a commercially-available load cell which are all built into the base of the plant’s pot. The design hides all of the electronics in a pleasant enclosure and is able to communicate relevant info wirelessly as well. The real story here, however, isn’t a novel use of an ESP32 chip, but rather out-of-the-box problem solving by using an atypical sensor to solve this problem. That’s not to say that you can’t ever use other sensors to directly monitor your garden and automate its health, though.

Fertilizing Plants With A Custom 3D-Printed Pump

For all but the most experienced gardeners and botanists, taking care of the soil around one’s plants can seem like an unsolvable mystery. Not only does soil need the correct amount of nutrients for plants to thrive, but it also needs a certain amount of moisture, correct pH, proper temperature, and a whole host of other qualities. And, since you can’t manage what you can’t measure, [Jan] created a unique setup for maintaining his plants, complete with custom nutrient pumps.

While it might seem like standard plant care on the surface, [Jan]’s project uses a peristaltic pump for the nutrient solution that is completely 3D printed with the exception of the rollers and the screws that hold the assembly together. With that out of the way, it was possible to begin adding this nutrient solution to the plants. The entire setup from the pump itself to the monitoring of the plants’ soil through an array of sensors is handled by an ESP32 running with help from ESPHome.

For anyone struggling with growing plants indoors, this project could be a great first step to improving vegetable yields or even just helping along a decorative houseplant. The real gem is the 3D printed pump, though, which may have wider applications for anyone with a 3D printer and who also needs something like an automatic coffee refilling machine.

Plant Communication Hack Chat

Join us on Wednesday, January 13th at noon Pacific for the Plant Communication Hack Chat with Lex Kravitz!

As far as conversation goes, plants are usually a pretty poor choice of partners. Sure, we’ve all heard that talking to you houseplants is supposed to be good for them, but expecting them to talk back in any meaningful way is likely to end in disappointment.

Or is it? For as simple and inanimate as plants appear to be, they actually have a rich set of behaviors. Plants can react to stimuli, moving toward attractants like light and nutrients and away from repellents. Some trees can secrete substances to prevent competitors crowding around them, by preventing their seedlings from ever even taking root. And we’ve known for a long time that plants can communicate with each other, through chemical signaling.

Plants are clearly capable of much more than just sitting there, but is there more to the story? Neuroscientist Lex Kravitz thinks so, which is why he has been wiring up his houseplants to sensitive amplifiers and looking for electrical signals. While the bulk of what we know about plant communications is centered on the chemical signals they send, it could be that there’s an electrical component to their behaviors too. Join us as Lex stops by the Hack Chat to talk about his plant communication experiments, and to see if it may someday be possible to listen in on what your plants are saying about you.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, January 13 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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