I have an hydrangea in a «self watering» vase (a Lechuza Cube) and I use a Parrot Flower Power to monitor soil moisture.

The soil moisture level sensor stays constant (17%-18%), watering the vase generates a peak for a very short time, but then the moisture level drops to the usual value (17%-18%)

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A similar sensor works as expected in a «normal» vase.

The Parrot Flower Power application is continuously telling me to add water, as the action has no effect on the measured moisture level.

  • Are similar values normal in a self watering vase?
  • Is the soil too dry for an hydrangea?
  • 1
    Is the Hydrangea showing signs of insufficient moisture, or does it look perfectly healthy? – Bamboo Sep 17 '14 at 14:40
  • Plant seems healthy, the question is more if such a sensor is usable with a pot with a water reservoir. – Matteo Sep 17 '14 at 14:44
  • I can't answer that, but I will say you should always judge how good or not conditions are for plants by the health of the plant concerned, rather than the other way around. I expect someone else can answer the other more technical aspect. – Bamboo Sep 17 '14 at 14:48
  • Do you have more than one sensors installed (in different pots)? If yes, try exchanging their places, to determine if it is a sensor issue. – VividD Feb 10 '18 at 13:39

Soil humidity is not the term to use. Humidity is the amount of water vapour in the air. Moisture level is what you are measuring. The tool you are using likely measures conductivity which increases when more water ions are present.

A self watering container uses capillary action to maintain a steady amount of water in the soil.

Depending on the amount of dissolved salts in the water and the length of time the container has been in use the soluble salt level could be a little higher and throwing off the tool.

I would just use my finger to determine the wetness of the soil. As a low tech reliable tool you can't beat it.

  • 1
    That's what I would recommend, using your finger. It's quite foolproof. – J. Musser Sep 17 '14 at 19:24
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    Thanks, I know, the plant does not have any problem, I am just a «gadget» type and wanted to try ... The sensors are working great with other plants ... – Matteo Sep 18 '14 at 6:12
  • 1
    I corrected the text regarding humidity vs moisture, thanks – Matteo Sep 18 '14 at 6:24

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