Horseradish spreads like crazy, via roots. You will have a difficult time getting rid of it. It is a big pest in my vegetable garden.

It takes a season or two for the roots and foliage to get really big. It will spread out little suckers everywhere.

No problem here keeping it from spreading as long as it spreads by roots and not seeds. It is planted in a 4x4 raised bed far away from anything else and I can mow around it. My question is about the plants from crowns that are bolting and going to seed. They are pretty white flowers on 3' plants but don't look like the plants grown from 6" long roots last year. Will they amount to anything root wise since they are bolting or should I just remove them to give more room to the volunteer plants growing from roots missed at fall harvest?

IDK whatever variety I have does not flower, so I can't comment on that...

Let me tell you a story about spreading of horseradish) I got tired of its spreading so I decided to grow it in the huge tree pot. I have rock hill from huge rocks, ground cover and some lilies grow there between the rocks. So I placed the pot on one of the solid rocks. It did pretty poor, so I decided to get rid of it in fall. What surprise it was to see, that I can't lift the pot. Horseradish root got through drainage hole, traveled about 2 feet under Vinca ground cover right on the rock surface, found the crack and rooted. Guess what? Now I have horseradish in my rock garden)Fortunately it doesn't spread as the crack is just enough for one plant, but I can't take it out - root breaks, and grow again. So be very careful)

I guess that would be 'Horserockish' then! I did some google searches and it seems that the flowering is expected on 2nd year plants so I assume that plants grown from 1 year crowns are considered 2nd year plants. I read conflicting info on whether to cut off the flowers or not. Some say to cut them so they don't propagate by seeds and to let the plant put the energy into growing roots.