Cheap Lee Valley Moisture Sensor

Here’s a simple way to monitor when your potted plants need water and – just as important – when they don’t.

Left in the soil, the probe continuously checks the moisture content, alerting you to low levels with a blinking red LED. As the soil dries, the rate of blinking increases to indicate urgency.

The included button-cell battery is good for about 6 months of use; a double flash tells you when it requires replacement.