How do I position my soil probe for my pot size?

Properly setting up your substrate sensor is essential for accurate and repeatable readings.

Incorrect placement can lead to misleading moisture, EC, and temperature data, affecting your ability to make informed irrigation and feeding decisions.

Best practices for inserting a soil probe

1

Keep prongs straight and level

• Always insert the prongs horizontally into the pot, not at an angle.

• Angled placement causes inconsistent depth readings, as the tip of the probe will be lower than the entry point.

• Multi-prong probes should be parallel to the soil surface, never inserted vertically, since moisture, EC, and temperature vary by depth.

2

Correct sensor height for reliable readings

Some probes are calibrated for specific insertion heights to measure conditions in the active root zone. Incorrect height placement can cause misleading data.

• Too high in the pot – Measures topsoil, which dries out faster than deeper layers.

• Too low down in the pot – Captures moisture and nutrients that may not be available to the plant’s roots.

3

Fully insert the sensor – No exposed prong

• Any part of the probe exposed to air will skew readings, particularly for moisture and EC.

• If moisture and EC appear lower than expected, check that the entire probe is in contact with the substrate.

4

Do not remove the sensor once placed

• Reinserting a sensor disrupts the substrate, causing air pockets that affect permittivity and moisture and EC readings.

• Leave the sensor in place for long-term, consistent monitoring.

5

Minimise air gaps around the probe

• Air pockets alter permittivity, which affects moisture and EC readings.

• If the sensor is not inserted firmly, gaps may form, misleading the device into reading lower moisture levels.

• After inserting the probe, gently press the substrate around it to ensure good contact (if possible)

Why should the entire sensor stay inside the pot?

For the most accurate readings, the sensor body should remain inside the pot to reflect the actual environmental conditions affecting the plant’s roots. If any part of the sensor is exposed, external factors can distort data.

Key reasons to keep the sensor inside the pot:

1. Consistent temperature readings – A sensor partially exposed to air may measure room temperature instead of substrate temperature, leading to inaccurate root zone data.

2. Accurate moisture and EC measurements – Exposed prongs may pick up dry air readings, making the substrate appear drier or lower in EC than it actually is.

3. Prevents external interference – Factors like air circulation, lighting, and nearby equipment can distort readings if the sensor is left outside the pot.

4. Stable data over time – Keeping the sensor fully inserted ensures consistent, repeatable data for better decision-making.

Substrate-specific considerations

Some substrates, like rockwool, are pre-formed and not designed for probe insertion. In these cases, placing the probe into the substrate is your only option.

By following these best practices, you’ll ensure reliable, real-time substrate data, helping you optimise your watering and feeding strategy for better plant health and higher yields.

Grow SubSenseDelta-T Wet 150Meter group Teros 12Acclima TDR-310WAcclima TDR-315NThe Grow Link Terra Link