Question
Why is it that the strength of processed horseradish varies so much? When is the best time to dig the roots?  Sometimes the finished product is very hot & on other occasions it is quite mild.  
      Thanks, -- Charles Wigginton
                 Dixon, Ill.  

Answer
Hi Charles,
Thanx for your question.  The University of Illinois says that horseradish gets hotter the finer you grind it.  Also, when processing if you add white vinegar immediately upon grinding this stops enzymatic processing within the roots and reduces the heat.  For hotter horseradish grind up the root and then let it sit for at least three minutes and then add the vinegar.  According to the University of Illinois, the best time to dig is in November before the ground freezes.  Do not dig the root while it is in active growth.  I hope this helps.
Tom