Horseradish Harvest and Propagation

I bought some seedlings of horseradish from you last spring. Most of them have grown nicely. I'm interested in splitting the roots so I'll have plenty to cultivate next year. I was wondering: should I split the roots now – only six months from first putting them into the ground – or should I leave them in the ground longer? I live in Delaware, USA (winters aren't too bad). Will the plants live outside, or do I need to bring them inside? When it comes to splitting the roots do I cut them down the middle with a knife or do I pull the roots apart?

Horseradish is hardy in zones 3 to 10 and since Delaware is zone 7 you can safely leave the plants outside for the winter. If you are not going to harvest any of the root the first fall then postpone the propagation until spring. To propagate dig the roots as early in spring as you can get into the soil, cut it across its length into as many slices as you need, with a minimum length for the slices of about 5 centimeters. Every little piece of root left in the soil will eventually grow into a new plant! If the plant makes multiple heads, then you can carefully cut these apart in spring or fall to make more plants.