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Soil Moisture Sensors
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VH400 Soil Moisture Sensor Probes

Buy VH400 Probe

Our VH400 series soil moisture sensor probes enable precise low cost monitoring of soil water content. 

Because our probe measures the dielectric constant of the soil using transmission line techniques, it is insensitive to water salinity, and will not corrode over time as does conductivity based probes. Our probes are small, rugged, and low power.  

Compared to other low cost sensor such as gypsum block sensors, our probes offer a rapid response time.  They can be inserted and take an accurate reading in under a second.  

Probes come in standard cable lengths of 2 meters, 5 meters and 10 meters.


VH400 - Vegetronix Soil Moisture Sensor Probe
VH400 - Soil Moisture Sensor Probe


Soil Moisture Sensor Probe Applications

  • Irrigation and sprinkler systems.
  • Moisture monitoring of bulk foods.
  • Rain and weather monitoring.
  • Environmental monitoring.
  • Water conservation applications.

Soil Moisture Sensor Probe Features

  • Extreme low cost with volume pricing. 
  • Not conductivity based.
  • Insensitive to salinity.
  • Probe does not corrode over time. 
  • Rugged design for long term use. 
  • Small size. 
  • Consumes less than 7mA for very low power operation.
  • Precise measurement.
  • Measures volumetric water content (VWC) or gravimetric water content (GWC).
  • Output Voltage is proportional to moisture level. 
  • Wide supply voltage range. 
  • Can be buried and is water proof. 
  • Probe is long and slender for wider use, including smaller potted plants.


Other Vegetronix Products of Interest

Soil Moisture Sensor Probe Pricing and Ordering Info

Contact us for pricing information. 

Part Number Description Price Purchase
VH400-2M Soil Moisture Sensor - 2 meter cable $37.95 Buy VH400 Probe
VH400-5M Soil Moisture Sensor - 5 meter cable $43.95 Buy VH400 Probe
VH400-10M Soil Moisture Sensor - 10 meter cable $53.95 Buy VH400 Probe

Soil Moisture Sensor Relay Boards

The quickest way to evaluate if the VH400 series is right for you is to also order some of our sensor relay boards.  The relay boards accept input from a single sensor and control a solid state or mechanical relay.  The relay contacts can be configured to close when wet, or open when wet.  The dry/wet threshold is easily set by an an on board variable resistor, which can be tuned with a small screwdriver.  With our relay boards, within minutes you'll be using your VH400 soil moisture probe to control, valves, alarms or home automation systems.  

Soil Moisture Sensor Probe Specifications

VH400 Sensor

Power consumption < 7mA
Supply Voltage 3.5V to 20 VDC.  
Dimensions See drawing below.
Power on to Output stable 400 ms
Output Impedance 10K ohms
Operational Temperature -40C to 85C
Accuracy at 25C 2%
Output 0 to 3V related to moisture content
Shell Color Red
Voltage Output Curves Curves,  Piecewise linear equations


Soil Moisture Sensor Probe Wiring Table

Bare Ground
Red POWER:  3.5V to 20 VDC.
Black OUT: (0 to 3V related  to moisture content.)

VH400 Soil Moisture Sensor Probe Drawing

VH400 Soil Moisture Sensor Probe Drawing

VH400 Soil Moisture sensor Drawing

Soil Moisture Sensor Probe Technical Literature

See our Soil Moisture Sensor Probe Application Notes for reference designs and information on how to use the soil moisture probe in larger systems. 


How to Get Started with the Soil Moisture Sensor Probe 

The best way to get started is to purchase a few low cost soil moisture sensor probes and try them out in your application. 

Buy VH400 Probe


Still have questions?

See our VH400 Soil Moisture Sensor Probe FAQ page.


Soil Moisture Sensor Instructional & Promotional Videos

How To Wire Up a Soil Moisture Sensor

The Techno Gardener shows you how to wire up a Vegetronix soil moisture sensor to a digital multimeter.

Soil Moisture Sensor as Water Level Sensor

The Techno Gardener demonstrates how a Vegetronix soil moisture sensor can be used as a water level sensor.

Soil Moisture Sensor Detects Clammy Hands

The Techno Gardener shows you how a Vegetronix soil moisture sensor can also be used to detect the moisture in your hands. It blows away gypsum block sensors with it's instantaneous moisture readings.



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