If you are a lover of all things spicy, you should be growing your own horseradish. Horseradish is cultivated for its pungent root. The plant is a large leaved herb that thrives in full sun but tolerates some shade. Plant horseradish in the spring as soon as the soil can be worked. Prepare the soil by digging down 8-10 inches and incorporating a generous amount of compost. Amend the soil further with either a 10-10-10 fertilizer in the amount of one pound per 100 square feet or well decayed manure. Let the plot stand undisturbed for a few days before planting the horseradish. Set the horseradish root cuttings or “sets” either vertically or at a 45-degree angle, spaced one foot apart from each other. Keep reading what to do here.
SOURCE:http://www.gardenoholic.com/when-and-how-to-harvest-horseradish-root/