WET KIT and WET-2 Sensor

    How to Buy
WET Sensor - measures moisture, EC and temperature Zoom
WET Kit – including WET SensorWET Kit – with carry case and HH2 readout unitWET SensorWET Sensor in substrate block


"Optimising the quality and yield of our fruit is a key priority for Clock House Farms. By knowing the exact EC and moisture levels hour by hour we have the data that enables us to react quickly to changing substrate conditions.

It is the immediacy of the data which the WET Sensor provides that is valuable to us, not just the excellent accuracy.

In terms of benefits that the WET Sensor provides, it not only gives us the confidence that we have optimal growing conditions at all times, it has also enabled us to reduce irrigation levels (whilst enhancing produce quality) - eliminating unnecessary water wastage and reducing expensive fertiliser costs."
Nick Deppe, Farm Manager
Clock House Farm, Kent, UK
"We have used the Delta-T Wet Sensor since its introduction. This device has allowed us to have precise control over the EC in our strawberry and raspberry substrate grown crops; delivering better quality, flavour and yields. We could not manage without this excellent tool now." Harriet Duncalfe
H&H Duncalfe, UK
"We've successfully integrated a large number of Delta-T Devices WET Sensors into our measurement systems. We use them continually - to provide EC, moisture and temperature measurements. This valuable data helps our customers to improve the yield and quality of commercial Cucumber and Tomato crops." Martin Drop
Hortitechnic, UK
  • Measures Water content, EC and Temperature
  • Measures directly within the root zone
  • Rapid checks of growing conditions
  • Ideal for precision irrigation

In just 5 seconds the WET Sensor checks 3 crucial variables that influence plant growth: water content, temperature and pore water conductivity (ECp), the EC of the water that is available to the plant.

VIDEO – how the WET Sensor works

Vital tool for precision horticulture

The WET Sensor is used throughout horticulture, especially by soft fruit growers and for crops grown in protected environments, where correct growing conditions are critical to both yield and flavour. The compact sensor can be inserted directly into the growing medium with minimal disturbance to either roots or shoots, and provides information for process optimisation, checking growing condition uniformity and precision irrigation.

WET Kitwet-1

WET Sensors are normally ordered as a complete kit that includes a WET Sensor, an HH2 Moisture Meter and a handy carry case. There are three types of Kit – each with a different set of substrate calibrations, including coir, peat and mineral wool. Please see below for further information on substrate calibrations and kits.

Fertigation and hydroponics

Where plants are grown in artificial substrates using hydroponic or fertigation systems, nutrients are routinely supplied in irrigation water. Nutrient levels are controlled by monitoring the water content and conductivity (EC) and adjusting the injection of liquid fertiliser into the irrigation water. The Delta-T WET Sensor excels in monitoring this vital information for precision irrigation.

Article featuring the WET Sensor – exploring Cultilene’s approach to measuring growing conditions in substrate slabs (HortiBiz 2015).

Container-grown shrubs and trees

Nutrients are sometimes provided by fertigation but are often provided by Controlled Release Fertilisers (CRF).

The rate at which these are taken up depends on several factors, including the weather conditions and precision irrigation regime.

The Delta-T Devices WET Sensor can be used to measure the EC within the growing media and so take much of the guesswork out of this process.

Soil salinity

If the irrigation water is recycled or abstracted from rivers and aquifers with high levels of dissolved salts, over time there can be a build up of soil salinity. Soil salinisation will eventually reduce crop yields. The WET Sensor is fast and efficient for sampling soil salinity, ensuring that farmers have the essential information they need to take remedial action as quickly as possible.

Readout and data logging

For portable applications, readout and data storage are handled by the HH2 Moisture Meter. Alternatively, the WET Sensor can be connected to a GP2 or GP1 Data Logger, making it possible to monitor growing conditions over a period of hours, days or longer. The GP2 and GP1’s smart relay capabilities allow them to control water content in response to EC or temperature.

WET Sensors used aboard China’s Tiangong-2 Space Station

The WET Sensor has been used by Chinese astronauts to conduct horticultural experiments in space. find out more.

Soil and horticultural substrate calibrations

If the WET Sensor is purchased with an HH2 Moisture Meter (as part of the WET Kit) it will be equipped with calibrations for generic mineral soils, organic soils, sand soils, clay soils, coir (coco fibre), peat based potting mixes, greenhouse ‘mineral’ soils, and Stonewool artificial mineral wool substrate (vertical and horizontal measurement).

If the WET Sensor is used with a GP1 Logger or GP2 logger it will be equipped by default with calibrations for generic mineral soils, organic soils, sand soils and clay soils. Two additional calibration upgrade packs are available – one of which contains calibrations for coir (coco fibre), peat based potting mixes, and greenhouse mineral soils, and one which contains Stonewool artificial wool substrate (vertical and horizontal measurement). See the accessories section of this page for more details.

WET Kit and standalone WET Sensor options

WET-2 KIT Comprises WET-2/d WET Sensor, HH2 Moisture Meter (including alkaline battery and comms cable), spare battery, USB-RS232 adapter cable, user manuals and WCC1 carrying case.

Includes sensor calibrations for generic mineral soils, organic soils, sand soils, clay soils, coir (coco fibre), peat based potting mixes, greenhouse ‘mineral’ soils, and Stonewool artificial mineral wool substrate (vertical and horizontal measurement).

WET-2/d Sensor with 1m cable and 25- way D-socket for use with HH2 Moisture Meter.
WET-2/w-05 Sensor with 5 m cable terminating in bare wires for use with GP1 or GP2.


The WET Sensor was developed in co-operation with:









Measurementvolumetric water contentPore water conductivityTemperature
Accuracy± 0.03 m3.m-3 (3%) see graph below ± 1.5°C
Soil moisture measurement rangeFull accuracy over:
0 to 1 m3.m-3
see graph below 0 to 50°C
Salinity range0 to 300 mS.m-1
Supplied with extended range calibrations which should be used for readings between 300 to 500 mS.m-1
Temperature range-5 to 50°C
OutputSerial TTL data providing permittivity, bulk conductivity and temperature, from which water content and pore water conductivity are calculated
Power requirement6-10 V, ~38 mA for 2.5s
Sample volume~500 ml
Sample volume is weighted towards soil immediately surrounding the rods
Dimensions and weightOverall: 120 x 45 x 13 mm
Rods: 68 mm x 3 mm diameter
Outer rods 68mm x 3.0 mm dia
Central rod 65 mm x 5.0 mm dia
Weight: 0.1 kg
Sensor calibrationsSensor calibrations supplied in WET Sensor EEPROM
Recalibration advised every 3 years (dependent on use)
Soil calibrations

Generalised Mineral ,Organic, Sand and Clay calibrations are supplied, specialist calibrations are available for horticultural substrates (please enquire at sales@delta-t.co.uk for more information) .

Wet Sensor chart


Product Resources

Data Sheets

Case Studies




Technical Notes

Sensor Calibration File Locator

Input your 5 or 6 digit serial number below (do not include a slash or space) to download your WET Sensor calibration file. (Example: 28073 or 120055).

IMPORTANT: If your serial number only has 4 digits, for example 22/19 – please add a zero before the last two digits – i.e. 22019

The serial number can be found on the sensor’s blue cable label. Contact tech.support@delta-t.co.uk if your serial number is not recognised - and we will assist you directly.

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