Moisture sensor data will not output data to Serial Monitor?
Your second print section will always fail.

You have:

if(millis() - printTime &gt; printInterval)   //Every 800 milliseconds, print a numerical, convert the state of the LED indicator


However, a bit before then you have:

if(millis()-printTime&gt;=printInterval)
{
  printTime=millis();


So millis() - printTime can never be greater than printInterval since you have just set printTime to millis(). So millis() - printTime will always be somewhere between 0 and printInterval - 1.

Consider combining your different printing routines into one single printing routine so you are comparing (and changing) the printTime only once.