VG400 Soil Moisture Sensor Probes

The VG400 has been discontinued. Please use our VH400 series probes instead.

VG400 - Vegetronix Soil Moisture Sensor Probe

Our VG400 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 consume under a milliamp of 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 1 second.

We offer two probes in the VG400 series. The VG400 which has an output range of 0 to 3V and the VG400-LV which has an output range of 0 to 1.8V related proportionally to water content. The VG400-LV is so power efficient that it can be run continuously for over 300 hours from a single coin battery, or over 5 years if the soil is sampled once per minute.

When choosing between the -LV and standard VG400, only use the -LV, if you have to power the probe with less than 3.3V.

Probes come standard with a 2 meter cable.

Also see our high frequency VH400 series soil moisture sensors, which are more sensitive in the higher VWC regions, at the cost of using slightly more power.

See our Soil Moisture Sensor Selector, to figure out which probe is right for your application.

Soil Moisture Sensor Probe Applications

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

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 600uA for very low power operation.
  • Precise measurement.
  • Measures volumetric water content (VWC) or gravimetric water content (GWC).
  • Patent pending technology.
  • 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

The VG400 has been discontinued. Please use our VH400 series probes instead.

Soil Moisture Sensor Relay Boards

The quickest way to evaluate if the VG400 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 VG400 soil moisture probe to control, valves, alarms or home automation systems.

Soil Moisture Sensor Probe Specifications

VG400 Probe (Standard Voltage Probe)

Power consumption < 800uA
Supply Voltage 3.3V to 20 VDC.
Dimensions See drawing below.
Power on to Output stable 400 ms
Output Impedance 100K ohms
Operational Temperature -40°C to 85°C
Output 0 to 3V related to moisture content
Shell Color Black
Voltage Output Curves Curves

VG400-LV (Ultra-Low Voltage Probe)

Power consumption < 600uA
Supply Voltage 2.0V to 20 VDC.
Dimensions See drawing below.
Power on to Output stable 400 ms
Output Impedance 100K ohms
Operational Temperature -40°C to 85°C
Output 0 to 1.8V related to moisture content
Shell Color Blue
Voltage Output Curves Curves

Soil Moisture Sensor Probe Wiring Table

Bare Ground
Red POWER: 3.3V to 20 VDC.
Black OUT: (0 to 3V proportional to moisture content.)

VG400 Soil Moisture Sensor Probe Drawing

VG400 Soil Moisture Sensor Probe Drawing

VG400 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 order a few low cost probes and try them out in your application. Use the red buttons above to make a purchase.