James H. Schutte
Plant Common Name
Bok Choy, Broccoli Raab, Chinese Cabbage, Choy Sum, Field Mustard, Pak Choi, Tatsoi, Turnip
Field mustard, turnip, bok choy, and broccoli raab are part of the complex of different cultivated plants known as Brassica rapa. They have been grown and selected in Eurasia for thousands of years for human consumption and livestock fodder. The origin of Brassica rapa is uncertain but believed center from South and Central Europe. It is now cultivated and naturalized worldwide.
These annual or biennial, cool-season plants typically have loose basal rosettes of broad fleshy green leaves with rough hairs and long stalks. The leaves may be deeply lobed or violin-shaped. Some varieties form round to oblong fleshy taproots of white or yellow. Tall sprays of bright yellow flowers appear in spring or summer, often in the second season of growth. Rattlebox seed capsules follow, opening to scatter many reddish-brown to black seeds. The seeds may also be used to make mustard.
These plants have been separated into several groups according to their various characteristics. These are the Narinosa, Chinensis, Perviridis, Rapifera and Ruvo Groups. The vegetables in each have many distinct characteristics.
Tatsoi, or rosette pak choi, is in this Narinosa group. It forms perfectly round, densely rosettes of small, spatula-shaped leaves. The remarkably hardy plants flourish in cool temperatures and are quick to bolt when temperatures heat up.
The Chinensis group includes pak choi, bok choy, choy sum, Chinese celery cabbage and Japanese cabbage. These are all chard-like plants with compact clusters of large, thick-stalked leaves that are tender and delicious when cooked.
Plants in the Pekinensis group (napa and Chinese cabbage) have thin, tender, mildly-flavored leaves. The pale to dark green, crinkled or smooth leaves usually have a broad, white, winged midrib.
Tendergreen and mustard spinach are included in the Perviridis group. They are grown for their, large, glossy, spatula-shaped leaves that are tender and delicious eaten raw or cooked. Some in this group have swollen roots that are sometimes pickled. They have a tendency to bolt and should only be grown in cool seasons.
The Rapifera group includes turnip, whose swollen taproot and and lush greens are prized edibles. Turnip varieties come in many shapes and sizes. The larger the root, the more pungent the flavor. Large turnips are grown for animal fodder.
Trendy broccoli raab, Italian turnip and ruvo kale belong to the Ruvo group which is characterized by tall, violin-shaped, dark green, often glossy leaves on long stems. The leaves and the loosely clustered, broccoli-like flower buds bring pungent flavors to salads and cooked dishes.
These cool weather crops prefer full sun and moderately fertile, humus-rich, neutral to slightly acid soil with ample drainage. They generally mature quickly, from 50 to 80 days depending on variety. Sow them in early spring before temperatures heat up or in late summer for fall harvesting. In areas with mild climates they make an excellent winter crop. Hot weather or prolonged chilly spells may cause them to flower ("bolt"), which usually results in bitter-tasting, dwindling plants. These brassicas are frost hardy and many will take a few degrees below freezing. They are not heavy feeders and may not need fertilizer if grown in rotation with nitrogen-fixing legumes. Some are shade-tolerant and good for planting between taller vegetables such as corn. These wonderful, variable greens are generally easy to grow and very tasty.