Plant horseradish in the spring, in full sun. Give it a spot where it can grow by itself. Its sturdy white roots are invasive. They wind themselves around the roots of other plants and aggressively take up more than their share of the garden.
Enrich the chosen spot with a large bucket each of well-rotted compost and manure. Work it into the soil with a spade to a depth of twice the root ball. These enrichments open the soil, facilitating drainage and plant growth. They feed the horseradish plant, helping it grow strong healthy roots. No additional fertilizer is necessary.
Trowel out a hole 2 inches bigger all around than the rootball of the horseradish plant. Place the plant in the hole, back fill with soil, and tamp it down firmly. Water well, ensuring the entire root system is soaked. Continue to water when the soil dries out.
Cut off the white flower panicles as they appear, to encourage more leafy growth.
Harvest horseradish in the fall. Use a spade -- horseradish roots are big. Excavate the soil around the roots until you have some of it exposed. Use the spade to chop off part of the root. Back fill with the soil you dug out, tamping it back around the plant.
Apply a thick, 4-inch layer of compost or well rotted manure around the base of the plant every spring. This feeds the horseradish plant and helps to keep the soil moist.
Prune the dead stems and leaves from the base of the plant after a severe frost or remove them in spring if it starts to snow before you have time.