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.

Agrivoltaics Is A Land Usage Hack For Maximum Productivity

Land tends to be a valuable thing. Outside of some weird projects in Dubai, by and large, they aren’t making any more of it. That means as we try to feed and power the ever-growing population of humanity, we need to think carefully about how we use the land we have.

The field of agrivoltaics concerns itself with the dual-use of land for both food production and power generation. It’s all about getting the most out of the the available land and available sunlight we have.

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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.

Plants compared side-by-side, with LED-illuminated plants growing way more than the sunlight-illuminated plants

Plant Growth Accelerated Tremendously With LEDs

[GreatScott!] was bummed to see his greenhouse be empty and lifeless in winter. So, he set out to take the greenhouse home with him. Well, at least, a small part of it. First, he decided to produce artificial sunlight, setting up a simple initial experiment for playing with different wavelength LEDs. How much can LEDs affect plant growth, really? This is the research direction that Würth Elektronik, supporting his project, has recently been expanding into. They’ve been working on extensive application notes, explaining the biological aspects of it for us — a treasure trove of resources available at no cost, that hackers can and should learn from.

Initially, [GreatScott!] obtained LEDs in four different colors – red, ‘hyper red’, deep blue, and daylight spectrum. The first three are valued because their specific wavelengths are absorbed well by plants. The use of daylight LEDs though has been controversial.  Nevertheless, he points out that the plant might require different wavelengths for things other than photosynthesis, and the daylight LEDs sure do help assess the plants visually as the experiment goes on.Four cut tapes of the LEDs used in this experiment, laid out side by side on the desk

Next, [GreatScott!] borrowed parts of Würth’s LED driver designs, creating an Arduino PWM driver with simple potentiometers. He used this to develop his own board to host the LEDs.

An aluminum PCB increases heat dissipation, prolonging the LEDs lifespan. [GreatScott!] reflowed the LEDs onto it with solder paste, only to find that the ‘hyper red’ LEDs died during the process. Thankfully, by the time this problem reared its head, he managed to obtain the official horticulture devkit, with an LED panel ready to go.

[GreatScott!’s] test subjects were Arugula plants, whose leaves you often find on prosciutto pizza. Having built a setup with two different sets of flower pots, one LED-adorned and one LED-less, he put both of them on his windowsill. The plants were equally exposed to sunlight and equally watered. The LED duty cycle was set to ballpark values.

The results were staggering, as you can see in the picture above — no variable changing except the LEDs being used. This experiment, even including a taste test with a pizza as a test substrate, was a huge success, and [GreatScott!] recommends that we hit Würth up for free samples as we embark on our own plant growth improvement journeys.

Horticulture (aka plant growing) is one of the areas where hackers, armed with troves of freely available knowledge, can make big strides — and we’re not even talking about the kind of plants our commenters are sure to mention. The field of plant growth is literally fruitful and ripe for the picking. You can accomplish a whole lot of change with surprisingly little effort. The value of the plants on your windowsill doesn’t have to be purely decorative, and a small desk-top setup you hack together, can easily scale up! Some hackers understand that, and we’ve started seeing automated growing solutions way before Raspberry Pi was even a thing. The best part is, that you only need a few LEDs to start.

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A tupperware-sized 3D-printed aeroponics cell, a grid-like contraption, with about 30 cloves of garlic in it, about five of them starting to grow. The cell is printed with white plastic, and there's a semi-transparent acrylic roof with LED strips attached to its underside, lifted about 3-4 inches above the garlic.

Aeroponic Cell Grows Garlic, Forwards CellSol Packets

Certain pictures draw attention like no other, and that’s what happened when we stumbled upon a Twitter post about “resuscitating supermarket garlic” by [Robots Everywhere]. The more we looked at this photo, the more questions popped up, and we couldn’t resist contacting the author on Twitter – here’s what we’ve learned!

This is an aeroponics cell – a contraption that creates suitable conditions for a plant to grow. The difference of aeroponics, when compared to soil or hydroponics methods, is that the plant isn’t being submerged in soil or water. Instead, its roots are held in the air and sprayed with water mist, providing both plenty of water but also an excess of oxygen, as well as a low-resistance space for accelerated root growth – all of these factors that dramatically accelerate nutrient absorption and development of the plant. This cell design only takes up a tiny bit of space on the kitchen countertop, and, in a week’s time, at least half of the cloves have sprouted!

Much like a garlic bulb, this project has layers to it – in that this aeroponic cell is also a CellSol node! The CellSol project is a distributed communication system that can use LoRa and WiFi for its physical layer, enabling you to build widely spanning mesh networks that even lets you connect your smartphone to it where it’s called for – say, as an internet-connected hub for other devices to send their data through. We’ve covered CellSol and it’s hacker-friendliness previously, and one of the intentions of this design is to show how any device with a bit of brains and a SX1276 module can help you form a local CellSol network, or participate in some larger volunteer-driven CellSol-powered effort.

If, like us, you’re looking at this picture and thinking “this is something I’d love to see on my desk”, [Robots Everywhere] has published the STL files for making a hydroponic cell like this at home, as well as all the code involved, and some demo videos. Hopefully, the amount of aeroponics projects in our tips line is only going to increase! We’ve covered Project EDEN before, a Hackaday Prize 2017 entry that works to perfect an aeroponics approach to create an indoor greenhouse. There’s also a slew of hydroponics projects to have graced our pages, from hardware store-built to 3D printed ones!

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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.

Germinate Seeds With The Help Of 3D Printing

Microgreens, also known as vegetable confetti, are all the rage in fancy restaurants around the globe. Raised from a variety of different vegetable seeds, they’re harvested just past the sprout period, but before they would qualify as baby greens – usually 10-14 days after planting. There’s a variety of ways to grow microgreens, and [Mr Ben] has developed a 3D printed rig to help.

The rig consists of two parts – a seed tray and a water tray underneath. The seed tray consists of a grid to house the broccoli seeds to be grown, with small holes in each grid pocket to allow drainage. They’re sized just under the minimum seed size to avoid the seeds falling through, and also provide a path for root growth. Beneath the seed tray, the water tray provides the required hydration for plant growth, and helps train the roots downward.

[Mr Ben] notes there are some possible improvements to the design. He suggests PETG would be the ideal filament to use for the prints, as it is foodsafe unlike PLA and ABS. Additionally, precautions could be taken to better seal the water tray to avoid it becoming a breeding ground for insects.

Overall, it’s a tidy project that makes growing these otherwise delicate and expensive greens much neater and tidier. There’s also plenty of scope out there to automate plant care, too. Video after the break.

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