Just in case. Bar graph display a bit too modern-looking for you? Well then you should check out [mircemk]’s OLED version that displays dual analog meters.

It’s been particularly useful for preventing overwatering in my Money Tree and Fig plants, which are quite sensitive to water levels. Before, I often struggled with determining the right time to water ...

This has the benefit that it can be readily driven by a microcontroller in much the same way as the familiar HD44780 character LCD ... the display to become a surprisingly-responsive VU meter.