Grove capacitive soil moisture sensor - intermediate voltages

Hi,
I dont have exactly 3.6V and 5.0V. I can get it if needed.
I have read the dryness values for 4.2V and 3.0V and hoped that I could find the dryness value for intermediate voltages by interpolation. Can I, or do I need either 3.6V or 5.0V?
Best regards
torben