Select the probe length so that the probess reach into the lower third of the substrate* so that the sensor can measure the available moisture over the entire root length.
We offer probes in lengths from 3 to 35 cm. It is important that the probes are completely inserted into the substrate and do not touch any drainage layer or roots.
To easily determine the correct probes length, you can use this calculator: Rod length calculator
* Substrate is the material in which the roots of a plant grow. It can consist of soil or various components such as coconut fibres, clay granules, perlite, activated carbon, compost, bark mulch or other mixtures, depending on the needs of the plant and the conditions in the pot or bed.