Hands-On Embedded Programming with C++17

Taking it further

You also need to have the following considerations:

• At this point, you can further refine the system by implementing plant-watering profiles to add dry periods or to adjust for certain soil types. You can add new RGB LED modes to make full use of the color choices available.
• The entire hardware could be built into an enclosure, to make it blend into the background, or maybe to make it more visible.
• The web interface could be extended to allow for controlling the trigger point and such from the browser, instead of having to use an MQTT client.
• In addition to the moisture sensor, you could also add a brightness sensor, a temperature sensor, and so on, to measure more aspects that affect the plant's health.
• For bonus points, ...