Smart Plant Moisture Monitor
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I built a plant moisture monitor
A short demonstration of the ESP32 plant monitor reading its capacitive soil-moisture sensor and showing the result through the 3D printed RGB status lamp.
Watch on YouTubeI gave my plant pixel art moods
Part 2 turns the monitor into a wireless device: the ESP32 sends live readings to a Cloudflare-backed PWA, which displays a different pixel-art plant character for each moisture state.
Watch on YouTube
About
An ESP32-powered plant monitor that reads a capacitive soil-moisture sensor, turns the result into a red or green status light, and sends live readings over Wi-Fi to an installable web app. I printed a case for the sensor, designed my own diffusing RGB lamp head, and created pixel-art plant characters for each moisture state. The working breadboard prototype cost £6.80 in project-specific materials.
Sensor and enclosure
The capacitive sensor reads the moisture level without leaving exposed metal in the soil. I found a printable case, printed its protective parts in white PLA and fitted them around the sensor.
RGB status lamp
I designed a small shade and base to turn the bare RGB LED into a more visible red or green status lamp, then printed both on a Bambu Lab P1S.
Current build
The working circuit uses an ESP32, a capacitive soil-moisture sensor, a common-cathode RGB LED, three resistors and Dupont wires on a breadboard. Project-specific materials came to £6.80, or £19.69 when the shared ESP32 starter kit is included. The two prints used 38.02 g of PLA.
Wireless app
The ESP32 sends a moisture reading over Wi-Fi every five minutes. A Cloudflare Worker stores the latest readings in D1 and serves a React PWA that can be installed on a phone. Instead of showing only a percentage, the app chooses a happy, worried, sad or sleeping pixel-art plant character for the current state.
Build Timeline
Sensor case printed
Printed and fit-tested the protective case around the capacitive moisture sensor.
Status lamp built
Printed the custom lamp head and tested the RGB LED circuit on a breadboard.
Tested in a plant
Placed the sensor in soil and recorded the monitor changing colour with the moisture reading.
Build video published
Shared the working plant monitor across YouTube, TikTok and Instagram.
Wireless PWA published
Connected the ESP32 over Wi-Fi, stored live readings in Cloudflare D1, and published an installable PWA with pixel-art moisture states.
What I Learned
- → Calibrate moisture thresholds in the plant's soil rather than relying on generic dry and wet values.
- → Powering the sensor from 3.3V keeps its analogue output within the ESP32 ADC's safe range.
- → Each RGB LED channel needs its own current-limiting resistor.
- → Thin white PLA diffuses the RGB LED well enough to make the colour change easier to see.
- → A device key can identify the ESP32 to the API without exposing a reusable secret in the public PWA bundle.
- → Saving the last successful reading in local storage keeps it visible during a temporary network outage without presenting stale data as current.
Discussion & Feedback
Have questions about this project? Built something similar? Share your thoughts!
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