Calibrating Soil Moisture

This guide will take you through calibrating your PLT-1's moisture sensor. The sensors come with a default calibration, so this method is only necessary if you want to make your own adjustments.

1. Take your PLT-1 out of the soil and clean off the probe. It's important to remove all dirt for the most accurate calibration.

2. Make sure the PLT-1 probe is sitting in the air or on a dry, non-conductive surface, and is plugged in.

3. Select Settings and then Devices & Services

Home Assistant Settings menu with Devices & services outlined in red

4. Select the ESPHome Integration

ESPHome integration tile in Home Assistant outlined in red

5. Select your PLT-1 device

ESPHome integration device list with the 1 device link under the PLT-1 outlined in red

6. Scroll down to the diagnostics section and select entity not shown.

PLT-1 Diagnostic card in Home Assistant with +1 entity not shown outlined in red

7. Select the entity "Soil ADC."

PLT-1 Diagnostic card in Home Assistant with the hidden Soil ADC entity outlined in red

8. Select the gear icon

Disabled Soil ADC entity dialog in Home Assistant with the gear icon outlined in red

9. Select Enable

Soil ADC entity settings in Home Assistant with the Enable button outlined in red

10. Give the sensor a minute for this new entity to populate.

11. Once the Soil ADC value is populated, enter it into the "Dry Voltage" entity.

PLT-1 Configuration card with the 100% Water Voltage and Dry Voltage boxes outlined in red

12. Now, place the stake/probe portion of the PLT-1 into a cup of water. Be careful not to submerge the entire sensor—only the exposed PCB below the "Apollo" label and the horizontal line can be exposed to water.

13. Grab the "Soil ADC" value again and enter it into the "100% Water Voltage" entity.

PLT-1 Diagnostic card in Home Assistant with the Soil ADC voltage reading outlined in red

14. You can now return your PLT-1 to your plant. Congratulations, your sensor is calibrated!