Horseradish (Armoracia rusticana) is a member of the Brassicaceae (Cruciferae) family, together with vegetables such as broccoli and radishes. Hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, it is an herbaceous perennial grown for its flavorful roots, which have been used and used as a condiment since early times. Horseradish flowers are small and white, growing in terminal panicles. They aren’t particularly essential in the entire life cycle of the plant, as horseradish produces little viable seed.
Horseradish is generally propagated from root cuttings that are either planted in spring or left in the ground after the fall harvest of the big roots. Big, coarse leaves seem first and may grow to be as many as 2 feet long on established plants. The stalks reach around 2 1/2 feet and in summertime produce flowers in the tops. Each flower has four petals with scores of buds in each panicle. Though the aromatic leaves are sometimes utilized in cooking, the flowers are normally not utilized. Horseradish may not flower in some years.
Horseradish flowers are pollinated either by insects or self-pollination. There’s some value in leaving them around the plants since they might play a part in attracting pollinators to the vegetable garden. Reducing the flower stalks for indoor structures won’t damage the plant and though the flowers aren’t showy, the flower heads, with their combination of buds and open flowers, might add fascination to mixed floral arrangements.
Neither leaves nor flowers are as important as the horseradish root, with its warm flavor. The best time to harvest the origins is in the second fall after planting, once the roots have grown big. Harvesting can occur any time in fall, but for best results, dig out the roots when cold weather has stopped development of their stems and leaves. Digging the big roots annually prevents the horseradish from propagating and taking up an excessive amount of garden space.
Though horseradish flowers are insignificant and of little use for reproductive, edible or decorative purposes, horseradish relatives include many common garden flowers. Colewort (Crambe cordifolia) is a tall cruciferous plant, hardy in USDA zones 5 through 8, which will be noted for its sprays of dainty white flowers. Biennial silver dollar plant (Lunaria annua) features either white or purple flowers and drop fruit that resembles transparent coins. It is hardy in USDA zones 5 through 9. Occasionally grown as an annual, perennial Brompton stock (Matthiola incana), hardy in USDA zones 7 through 10, attributes lush clove-scented flower heads.