How accurate are soil moisture sensors?

Smart sensors are typically accurate to within 3-5% volumetric water content. Analog meters show relative wetness (dry/moist/wet) rather than exact percentages. For home gardening, both approaches work.

Can I leave a moisture sensor in the ground permanently?

Smart sensors (ECOWITT, Sensoterra) are designed for permanent outdoor deployment. Analog meters should be removed after each reading — leaving the metal probe in soil accelerates corrosion.

Best Soil Moisture Sensors 2026