Does horseradish need a period of cold weather? Can it be grown inside without a rest period?
Certified GKH Gardening Expert
While it's not generally recommended to grow them indoors, you can dig horseradish roots in the fall before the ground freezes and replant in a soil-filled container. Cover the roots with a 6- to 8-inch layer of damp sand or sawdust. Keep the soil evenly moist. Give the roots a cool, dark rest in cool temperatures from 50-60 degrees F./10-15 C. (such as in a garage). As the plants grow and leaves reach 8 inches in height, remove soil from the upper end of the main root and trim away small side roots. Then mound the soil up to its original level, repeating in a few weeks.
Here is an article for growing horseradish plants that you may find helpful: https://www.gardeningknowhow.com/edible/herbs/horseradish/growing-horseradish-how-to-grow-horseradish.htm