Some soil compositions can be too porous for the probe to read the moisture consistently. The way to improve the reading is to partially wrap the probe with a small piece of cloth. This will help retain some moisture around the probe and should improve the reading.
Requirements
-a small piece of cloth (1-1/2" x 2")
-a small rubberband
Steps
Wrap the cloth around the probe and secure it with the rubber (see images below)