Gen3 Spruce Sensor Guide

Contents

The Gen3 Spruce Soil Moisture Sensor

The Gen3 Spruce Sensor measures soil moisture and temperature and then wirelessly transmits the data to a compatible base station. The sensors can be used indoors or outdoors to monitor or control watering.

When paired with the Spruce Controller, the water schedule can be set to use the reported soil moisture values to adjust water frequency.

The sensors can also be paired to the Samsung SmartThings hub and used to monitor or integrate into automation’s to trigger actions based on the soil moisture or temperature.

Join and Remove the Sensor

The Gen3 Spruce Sensor uses the included magnet to add or remove the sensor from the wireless network. A Spruce Gen2 Controller or Samsung SmartThings hub is required.

Measurements

Poll interval is no longer adjustable. Any changes to poll will not change the check or reporting interval. This applies to Spruce and SmartThings apps.

  • The Gen3 Spruce Sensor checks for changes in soil moisture and temperature every minute. If either has changed the updated value is immediately sent.
  • A repeat value will be sent after 1 hour if there has been no change
  • A measurement can be taken immediately by tapping the magnet to the leaf on the lid. The sensor must already be paired to the system otherwise the pairing search will be initiated instead.
  • The grass in your lawn will typically have a root zone depth down to about 6 inches. The top surface of the soil can be drastically dryer than the soil a few inches below.
  • The soil moisture is measured approximately 3-5 inches below the cap of the sensor in the blue shaded region.
Soil moisture and temperature measurements

Battery Replacement

  • The Gen3 Spruce Sensor uses 1x CR123 battery
  • Works with rechargeable CR123 battery
  • Increased battery life. Battery life will depend on environmental conditions and battery capacity, rechargeable batteries are typically lower capacity which may shorten effective battery life.
  • See below for battery replacement animations and instructions:

You may notice some condensation inside the sensor. This normally does not cause any problems as the electronics are fully sealed.

  1. Rotate sensor cap counter clockwise approximately 1/4 turn
  2. Pull cap to remove
  3. Swap the battery by aligning the + marked in the sensor with the+ on the new battery
  4. Install the cap by aligning the locking tabs, then rotating clockwise until the 4 edges of the sensor are aligned
  5. The sensor will typically remember that it is joined to the system and will need no other action to begin operation
  6. Tap the leaf with the magnet to trigger an immediate moisture and temperature check. The sensor should blink green 2x and send the newest moisture and temperature data

Spruce Controller

The Gen3 Spruce Sensor connects directly to the Spruce Gen2 Controller similar to previous sensors. The moisture, temperature, battery and signal strength is available in the Spruce app and updated periodically depending on how often the values change.

  • Each zone can be assigned 1 soil moisture sensor with up to 16 individual watering zones. See Zone and Sensor Assignment
  • Watering zones may share a soil moisture sensor, but restrictions apply. See Can I assign the same sensor to multiple zones?
  • The model number PS-SPRZMS-SLP3 is identified during the pairing process
  • The device serial number will be entered into the device settings page automatically during the pairing process

Spruce Moisture Sensor Chart

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Samsung SmartThings

The SmartThings hub is NOT required when the Spruce Controller is used

The Gen3 Spruce Sensor is a direct replacement for previous Spruce sensors and connects in the same way to the Samsung SmartThings hub. The sensor has been tested to connect with the SmartThings Classic App. After the sensor has been joined to the system, it can also be used in the newer SmartThings app.

The SmartThings Classic app is required for the sensors to be detected in the join process

  • Connect directly to a Samsung SmartThings hub
  • Send the sensor data to Spruce app with Spruce Gen2 + SmartThings Connect
  • The SmartThings Classic app is required for the sensors to be detected in the join process
  • After successful join, the sensors can be used in both SmartThings apps
  • The battery will drop from 100% very quickly but remain around 90%, this is normal
  • SmartThings only reports a new humidity or temperature value when there is a change in value

SmartThings with Humidity Chart

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The Spruce Sensors can be used with many of the standard SmartThings automation’s because they use the common humidity and temperature attributes.

  • The sensors can be used to monitor house plants or trigger external valves or other devices using the SmartThings app automation’s.
  • The sensors can be used as temperature sensors in SmartThings app automation’s.
  • In the videos below we show how to add a notification that a house plant needs water. The first video uses the Humidity Alert SmartApp in the SmartThings Classic app. The 2nd video uses custom automation’s in the newer SmartThings app.
Humidity Alert in SmartThings Classic
Custom Automation notification for low soil moisture

Troubleshooting

Sensor is not reporting new values

Soil Moisture is not changing but temperature is

Sensor is in a puddle and does not read 100%

  • See What is my target moisture level? The sensors are calibrated to volumetric water content which is the % of water in soil and typically measure a maximum of around 45%.

Where is the Serial Number?

  • The serial number is inside the sensor, under the battery
  • The Spruce app also fills in the serial number automatically when the sensor is joined to the system. The serial number is located in the Spruce app at Device Settings>>Spruce Sensors>>Sensor Name

Installation Tips

  • Range can be maximized by orienting the sensor so the Spruce logo located on the probe faces the nearest access point (Spruce Controller, hub, or repeater). See Wireless Range 101
  • In compacted or dense soil, create a hole slightly larger than the sensor probe. Then fill the hole with potting soil. Install the sensor into this new soil. The increased drainage will provide a balanced response to changing soil moisture conditions.
  • Add range extenders to maximize range. See Adding a Range Extender

Calibration

The Gen3 Spruce sensor is factory zero calibrated, but the same operation can be replicated anytime.

  • The calibration is automatically committed to memory and can be changed by performing the calibration again
  • Changing the battery will not affect the calibration values; calibrations will not be reset when the battery is removed
  • If the calibration fails, the values are reset to default, and the calibration should be performed again
  • Additional information on soil moisture levels at What is my target moisture level?

Zero calibration

  1. Disconnect from the system. The sensor must not be paired for the calibration process.
  2. Thoroughly clean and dry the probe
  3. Hold the sensor by the blue plastic, do not touch the black probe during this process
  4. Hold the magnet to the leaf for ~ 10 seconds
    • If the LED flashes green 2x (green|red|green | red | red | red | red) the calibration was successful.
    • If the LED flashes red 2x (red | red) the calibration was unsuccessful. This can be caused by a dirty or wet probe.
    • If the LED blinks 2x red, then alternates red and green for ~15 seconds, the magnet was not held to the magnet sensor for a long enough time, and the join processes was initiated instead of the calibration.
  5. After the calibration, the dry sensor should measure 0-1%

Scale Calibration

  1. Perform the zero calibration before proceeding
  2. Put the probe in a glass of water with the water level up to the white leaf. The water level does not have to be exact but should be up to or partially covering the white leaf on the probe.
  3. Hold the sensor by the blue plastic, do not touch the black probe during this process
  4. Hold the magnet to the leaf for ~ 10 seconds
    • If the LED flashes green 3x (green | red | green | red | green | red | red) the calibration was successful .
    • If the LED flashes red 2x (red | red) the calibration was unsuccessful.
    • If the LED blinks 2x red, then alternates red and green for ~15 seconds, the magnet was not held to the magnet sensor for a long enough time, and the join processes was initiated instead of the calibration.
  5. After the calibration, the sensor in water should measure 44-45%

You may now re-join the sensor.

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