Plant watering reminder

The basil keeps dying, and it is not the basil's fault. So: a capacitive soil moisture sensor, a microcontroller and a small buzzer that goes off when the soil gets too dry.

What works

• The capacitive sensor is much better than the cheap resistive kind, which corroded within a week.
• Reading once an hour keeps the battery usage low.
• A threshold with a little hysteresis, so it does not beep on and off around the limit.

What does not

The buzzer is too quiet. It beeps politely in the kitchen while I am in the other room. Next step is either a louder buzzer or a small LED that stays on until the pot is watered.