Horseradish (Armoracia rusticana)
The large fleshy roots are strongly aromatic, and, like onions, can make your eyes water as you prepare them. The large coarse leaves have no aroma and no known uses.
Horseradish will spread to fill whatever space is available, so use restraint when planting. It is grown by dividing and replanting the root. A piece about 8 inches long is ideal. It likes deep, moist soil but will grow almost anywhere.
Plant as early in the spring as you can. Till or spade the area to a depth of 8 inches. Dig a hole or furrow 4-6 inches deep. Put a handful of compost in the bottom and cover it with 2 inches of soil.
Push each root piece into the soil at an angle rather than straight up and down. This will help the roots that grow along the length of each cutting to grow straight down without getting tangled up. The top of the root cutting should be 2 inches below the soil. The "downward end" of purchased root cuttings will be cut at a slant. If you take cuttings from a freind's garden, mark your roots in the same way.