A soil moisture sensor ensures your plants aren't watered when the ground is still wet. The sensor measures how moist the soil is and stops the watering is extra water isn't necessary. That way, you never overwater and actually save water. The GARDENA soil moisture sensor works together with the water control or pump. You can use it for flower beds, vegetable gardens, or borders. You can easily place a soil moisture sensor into the ground. This way, your garden stays healthy without you constantly having to check if the soil is dry or not.