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

Plant Growth Accelerated Tremendously With LEDs

April 30, 2022 by Arya Voronova 37 Comments

[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.

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.

Continue reading “Plant Growth Accelerated Tremendously With LEDs” →

A soil moisture sensor with silkscreen chipped and copper corroded

Soil Moisture Sensor Coating Lessons Learned The Hard Way

March 2, 2022 by Arya Voronova 35 Comments

Ever wanted to measure soil moisture? Common “soil moisture meter module arduino raspberry compatible free shipping” PCBs might deceive you with their ascetic looks. Today, [Raphael (@rbaron_)] is here to teach us (Twitter, unrolled) what it takes to build a soil-embedded sensor that can actually survive contact with a plant.

As the picture might hint, waterproofing is of paramount importance, and soldermask doesn’t quite cut it. Raphael describes his journey of figuring out approaches and coatings that would last, starting from simply using nail polish, and ending with the current option – a rotisserie-like device that rotates sensors as the coating applied to them dries, mitigating a certain kind of structural failure observed long-term. With plenty of illustrative pictures and even a video of the rotisserie device in action, you’ll quickly learn things that took time and effort for Raphael to figure out.

This isn’t the first time Raphael shares some design battlefield stories and lessons with us – he has taught us about overall capacitive moisture sensor principles, too! If that interests you, we’ve covered quite a few moisture sensor designs, from cheap but hardy two-nails designs to flip-dot-equipped ones, and some of us take the commercial designs and upgrade them!

We thank [Chaos] for sharing this with us!

Continue reading “Soil Moisture Sensor Coating Lessons Learned The Hard Way” →

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

January 16, 2022 by Arya Voronova 16 Comments

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!

Continue reading “Aeroponic Cell Grows Garlic, Forwards CellSol Packets” →

Photo of an automated plant watering system attached to four potted plants.

Automation Allows You To Leaf Your Plants Alone

November 5, 2021 by Stephen Ogier 11 Comments

The greatest threat to a potted plant stems from its owner’s forgetfulness, but [Sasa Karanovic] has created an automation system that will keep his plants from getting too thirsty. Over the past year [Sasa] has been documenting an elegant system for monitoring and watering plants which has now blossomed into a fully automated solution.

If you haven’t seen the earlier stages of the project, they’re definitely worth checking out. The short version is that [Sasa] has developed a watering system that uses I²C to communicate with soil moisture, temperature, and light sensors as well as to control solenoids that allow for individual plants to be watered as needed. An ESP32 serves as a bridge, allowing for the sensors to be read and the water to be dispensed via an HTTP interface.

In this final part, [Sasa] integrates his watering system into a home automation system. He uses a MySQL database to store logs of sensor data and watering activity, and n8n to automate measurement and watering. If something isn’t quite right, the system will even send him a Telegram notification that something is amiss.

If you think automation might be the best way to save your plants from a slow death, [Sasa] has kindly shared his excellent work on GitHub. Even if you don’t have a green thumb, this is still a great example of how to develop a home automation solution from scratch. If you’re more interested in television than gardening, check out [Sasa]’s approach to replacing a remote control with a web interface!

Continue reading “Automation Allows You To Leaf Your Plants Alone” →

Green Roofs Could Help Improve Solar Panel Efficiency

September 20, 2021 by Lewin Day 83 Comments

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.

Continue reading “Green Roofs Could Help Improve Solar Panel Efficiency” →

Soil Moisture Sensors, How Do They Work?

May 17, 2021 by Donald Papp 19 Comments

In a way, the magic of a soil moisture sensor’s functionality boils down to a simple RC circuit. But of course, in practice there is a bit more to it than that. [rbaron] explains exactly how capacitive soil moisture sensors work simply, clearly, and concisely. He also shows, with a short video, exactly how their output changes in response to their environment, and explains how it informed his own sensor design.

At its heart, a moisture sensor measures how quickly (or slowly) a capacitor charges through a resistor, but in these sensors the capacitor is not a literal component, but is formed by two PCB traces that are near one another. Their capacitance — and therefore their charging rate — changes in response to how much water is around them. By measuring this effect on a probe sunk into dirt, the sensor can therefore indirectly measure the amount of water in the soil.

This ties into his own work on b-parasite: an open-source, all-in-one wireless soil moisture sensor (which was also a runner-up in our Earth Day contest) that broadcasts over BLE and even includes temperature readings. One thing to be mindful of if you are making your own PCBs or ordering them from a fab house is that passing current through metal in a moist environment is a recipe for oxidation, so it’s important not to expose bare traces to wet soil. A good coated PCB should avoid this problem, but one alternative we have seen proposed is to use graphite rods in place of metal.

Your Plants Can Take Care Of Themselves Now

March 14, 2021 by Bryan Cockfield 41 Comments

One of [Sasa]’s life goals is to be able to sit back in his home and watch as robots perform all of his work for him. In order to work towards this goal, he has decided to start with some home automation which will take care of all of his house plants for him. This project is built from the ground up, too, and is the first part of a series of videos which will outline the construction of a complete, open-source plant care machine.

The first video starts with the sensors for the plants. [Sasa] decided to go with a completely custom module based on the STM32 microcontroller since commercial offerings had poor communications designs and other flaws. The small board is designed to be placed in the soil, and has sensors for soil moisture as well as other sensors for amount of light available and the ambient temperature. The improvements over the commercial modules include communication over I2C, allowing a large number of modules to communicate over a minimum of wires and be arranged in any way needed.

For this build everything is open-source and available on [Sasa]’s GitHub page, including PCB layouts and code for the microcontrollers. We’re looking forward to the rest of the videos where he plans to lay out the central unit for handling all of these sensors, and a custom dashboard for controlling them as well. Perhaps there will also be an option for adding a way to physically listen to the plants communicate their needs as well.

Continue reading “Your Plants Can Take Care Of Themselves Now” →