The soil moisture sensor or the hygrometer is mostly used to detect the humidity of the soil. It is perfect to build an automatic watering system.
eBay - Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino
$2.17
eBay
Amazon.com - 5pcs Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino
Amazon.com
Amazon.de - 5pcs Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino
Amazon.de
Amazon.co.uk - Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino (3 pieces)
Amazon.co.uk
Amazon.es - Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino (5 pieces)
Amazon.es
Aliexpress - 5pcs Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino
$2.24
Aliexpress
Banggood - Soil Hygrometer/ Soil Moisture Sensor YL-69/HL-69 For Arduino - CN warehouse
$9.99
Banggood.com
Learn how to use the YL-69/HL-69 soil moisture sensor with Arduino: Guide for Soil Moisture Sensor YL-69 or HL-69 with Arduino.