Horseradish is a perennial in USDA zones 3–9. After the first frost in autumn kills the leaves, the root is dug and divided. The main root is harvested and one or more large offshoots of the main root are replanted to produce next year’s crop. Horseradish left undisturbed in the garden spreads via underground shoots and can become invasive. Horseradish grows very well in a container of at least 15 gallons.