i bought 3 roots at a super HEB in Burleson, tx for apx $6 lb. total apx$20. cut them into a dozen+ pieces and have the first ones (4) coming up around the potatoes.
i planted some 3 yrs ago but they have gotten shaded out. they get hit by harliquen bugs and snails bad also.

do you plant and cover the whole horseradish root? or do you leave any part exposed?
also, would it work as a potted plant like with my herbs?

i planted them 1-2" deep. due to cold soil here this spring it took them a long time to come up 2 weeks+. i am in DFW area.

I am sure you are aware of this, but if not: horseradish spreads like wildfire. Your one root will be 100 before you know it, so wall it off.