Horseradish

http://www.organicgardening.com/learn-and-grow/horseradish?page=0,0&cm_mmc=GardentoTableNL-_-2011_03_02-_-learnandgrow-_-horseradish

Ironic that so many gardeners have trouble keeping horseradish from spreading out of control, and I can barely keep it alive.