When should I harvest horseradish?
The roots of horseradish make their greatest growth in late summer and early fall. To obtain the best crop, delay harvesting horseradish until late October or November.
Carefully dig the horseradish and cut off the foliage about 1 inch above the crown. Store horseradish in a refrigerator or root cellar at a temperature of 32 to 40 degrees Fahrenheit and a relative humidity of 90 to 95 percent. When storing horseradish, keep the roots out of light. Light will turn the roots green.
Gardeners can also leave some horseradish in the ground over winter. Harvest the remaining crop in early spring before growth resumes.