Zigbee soil sensor

measure ground moisture and temperature

Introduction

I was looking for an outdoor sensor to measure the ground humidity to see if I need to water the plants outside.

I found this soil sensor, with a solar panel, which could do the job!

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Specifications
Zigbee2MQTT
Home Assistant
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Other plant sensors

Specifications

These are the specifications for this sensor:

Key	Value
Battery	AA 1.2V * 3 Ni-MH battery (Rechargeable)
Solar Charging Current	35mA
Communication Protocol	Zigbee 3.0
Wireless Protocol	Zigbee IEEE 802.15.4
Wireless Distance	50M
Waterproof Level	IP66
Temperature Detection Range	-10～60℃ (14℉～140℉)
Moisture Detection Range	0～100%RH (Non-Condensing)
Maximum Detection Range of Electrical Conductivity	20ms/cm
Temperature Detection Accuracy	0.5℃ (Adjustable)
Moisture Detection Accuracy	5%RH (Adjustable)
Electrical Conductivity Detection Accuracy	3%FS 0.01ms/cm
Time Span of Detection	10min (Adjustable)
Working Temperature	-10 ~ 60℃ (14 ~ 140℉)
Working Humidity	0 ~ 100%RH (Non-Condensing)
Size	78mm x 78mm x 146mm

Zigbee soil sensor (AliExpress) | NAS-STH02B2

Installation

To install it, press only the metal pins full in the ground.

If you have a model which is battery powered, you can reach those via the bottom and unscrew the panel.

Zigbee2MQTT

The model is registered as NAS-STH02B2 in Zigbee2MQTT.

To pair it, there is a button underneath the head that you need to press for a few seconds to get in pairing mode.

  {
    "battery": 81,
    "ec": 1,
    "fertility": "normal",
    "humidity": 0,
    "humidity_alarm": "lower_alarm",
    "humidity_sensitivity": 2,
    "last_seen": "2025-01-12T10:01:00.904Z",
    "linkquality": 94,
    "max_humidity_alarm": 70,
    "max_temperature_alarm": 40,
    "min_humidity_alarm": 20,
    "min_temperature_alarm": 10,
    "schedule_periodic": 5,
    "temperature": 16.4,
    "temperature_alarm": "cancel",
    "temperature_f": 61.5,
    "temperature_sensitivity": 0.5
  }

Home Assistant

The sensor generates a lot of entities, but the main ones are temperature and humidity. There are a lot of alarms you can define and end up as entities.