Long post, sorry in advance.
I've been growing herbs and leafy greens indoors for a while. I bought a 2nd hand AeroGarden (RIP), tried Click & Grow, tried a couple of cheaper alternatives. My main frustration with all of them was the same thing I never actually knew what was happening inside the substrate. The plants would either look a bit sad and I'd have no idea if they were thirsty, waterlogged, or just unhappy. The systems basically just run on a timer and hope for the best.
I work in electronics, so eventually I just got annoyed enough to build something myself as a side project.
The short version of what I built: it's a small enclosed crate-style system that measures substrate moisture without any probes touching the substrate. It uses the electrical properties of the growing medium itself to detect how wet or dry it is basically the same principle used in industrial soil sensing. It also has a small load cell underneath so it can cross-check that reading with actual weight change after watering. If both agree the substrate is dry, it triggers the mister. If they disagree, it flags it rather than guessing.
It also handles its own lighting cycle and has a little display where you pick your crop type, and it takes it from there.
The two honest downsides:
The substrate isn't off-the-shelf I've had to develop my own mix (it comes pressed into a kind of brick format that sits in the tray). The dielectric properties of standard perlite/coco mixes interfere with the sensing approach I'm using, so I needed something consistent.
The nutrient solution is also custom not dramatically different from standard hydroponic nutrients, but calibrated for how this system waters.
Other than that, it's been running more reliably than anything I've bought, and I actually know what's happening inside it at any given moment.
I'm not trying to sell anything this is genuinely a personal project I've been tinkering with. But I'm curious: does this solve a problem that other people actually have? Or am I just a nerd who over-engineered a herb garden? 😅
Particularly interested in whether the substrate/nutrient limitation would put people off, or if that's not a big deal if the system actually works properly.