Gardena smart system smart Sensor 19040 Operator's Manual page 10

To plant the sensor:
CAUTION!
The measuring area will only measure the soil moisture correctly
if the measuring area is in full contact with the ground on all sides!
No air should be trapped at the measuring area in the ground.
Remove the soil:
1. Dig a funnel-shaped hole in the ground
2. Break up the soil
3. Make sure there are no metal objects near the sensor.
10
(8)
(8)
removed and take out any stones and thick roots.
(8)
at least 20 cm deep.