Sensor placement is closely related to root development.
With the Growficient sensors you can easily see the water uptake in your substrate. For a good insight into this uptake, it is therefore important to place the sensor at the location where the main root development and activity takes place.
At the beginning of your cultivation you may (for generative control) place the substrate blocks next to the hole (or on top of the plastic) of the substrate mat. In this case, you will only have root formation in the blocks, so it is better to place the sensor directly in the block itself.
From the side or top?
Depending on the volume, height, and type of substrate of the blocks, the sensor can be placed on the side, or at the top. The placement depends mainly on the length of the sensor pins. After all, you only want to measure the volume of the block, so the pins shouldn't stick through the mat at the bottom, for example.
Therefore, sensors with long pins (95mm) are recommended to be placed on the side of the block, with the pins horizontally, about halfway through the block. As shown in the following photo.
However, sensors with short pins (70mm) can be placed from the top of the block. It is then recommended to place a second (empty) block next to it so prevent the block from falling over due to the weight of the plant. Again, make sure that the sensor pins are not poking through the plastic in the bottom. Otherwise you will unintentionally get a lot of root formation in your substrate already.
When the blocks are eventually placed on the substrate, you will also have more root activity in the substrate. From this moment on the sensors can be transferred from the block directly to the substrate, according to the standard sensor placement (Growficient - Installation manual - Sensor - Slabs (EN).pdf).
It is advisable to wait a couple of days until the block is well rooted-in in the substrate, so you can see good water-uptake in the graphs.
For more information about placing the sensors at the beginning of the cultivation, see also this article on our website: https://www.growficient.com/en/well-begun-is-half-done/