Turnips, which are root vegetables belonging to the mustard family, Brassicaceae, do indeed produce seeds as part of their natural reproductive process. The turnip, scientifically known as Brassica rapa, is cultivated primarily for its swollen, fleshy taproot and leafy greens. Like its close relatives, such as cabbage and bok choy, the turnip uses seeds to propagate the species.
The Turnip Life Cycle and Seed Production
Turnips are generally considered a biennial plant, meaning their full life cycle spans two growing seasons. During the first year, the plant develops the edible root and a rosette of leaves, storing carbohydrates necessary for reproduction. To produce seeds, the plant must undergo vernalization, a period of cold temperatures, typically at least six weeks below 7°C (45°F).
When the weather warms in the second year, the turnip will “bolt,” sending up a tall, rigid flower stalk. This stalk produces numerous small, cross-shaped, yellow flowers, a distinguishing feature of the Brassicaceae family. After successful pollination, these flowers develop into narrow, elongated seed pods known as siliques. These pods house the developing seeds.
Identification and Uses of Turnip Seeds
The seeds found within the siliques are small, rounded, and typically dark in color, ranging from reddish-brown to black. Their size is characteristic of many seeds within the mustard family. These seeds are the primary means by which gardeners and farmers sow new crops, as turnips are best grown by directly planting the seed into the soil.
Turnip seeds have uses beyond planting due to their connection to other oilseed crops in the Brassica genus. They possess a peppery flavor, similar to mustard seeds, and can be used in culinary applications, such as sprouting for salads. Commercially, certain varieties of Brassica rapa are pressed for oil, which is a significant global source of vegetable oil and a high-protein feed source for livestock.
Harvesting and Saving Turnip Seeds
For a home gardener interested in saving turnip seeds, timing the harvest is important. The seed pods must be allowed to completely dry on the stalk, changing color from green to a brittle, light brown or tan. Harvesting too early will result in immature, non-viable seeds, so wait until the stalks are fully desiccated.
Once the stalks are dry, they can be cut and placed over a container or drop cloth to catch any seeds that may naturally fall out. The next step is threshing, where the dried pods are gently crushed to release the tiny seeds inside. The seeds must then be separated from the chaff, or remaining plant debris, through winnowing or screening. After cleaning, store the seeds in a cool, dark, and dry environment to maintain viability.