Brassica rapa var. rosularis
Common Name: tat soi 
Type: Annual
Family: Brassicaceae
Zone: 2 to 11
Height: 0.50 to 1.00 feet
Spread: 1.00 to 1.50 feet
Bloom Time: Flowers not showy
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Suggested Use: Annual, Vegetable

Culture

Tat soi is a cool weather crop. Prostrate varieties are resistant to cold down to -5 to -10 degrees F.; upright varieties will tolerate a light frost. Sow seeds in fertile moisture-retentive soil in late spring for a spring/summer crop and in late summer for a fall crop. Seeds may also be sown earlier in spring if given protection with row covers or in summer although high temperatures or lack of moisture may encourage the plants to bolt. Thin seedlings to 6” to 8” apart with 12” to 18” between rows. If larger rosettes are desired, thin to 12” to 16” apart. As they reach desired size, harvest individual leaves, the center rosette, or the entire head (about an inch above the base of the plant to encourage regrowth). Rosettes may take up to 7 to 8 weeks to mature.

Noteworthy Characteristics

Brassica rapa<.em> var. rosularis, known as tat soi, rosette pak choi or flat cabbage, has very thick lustrous black green leaves arranged in a rosette of regular, concentric circles, with prostrate and upright varieties. The leaves vary from flat and smooth to puckered and crepe-like. This is an attractive plant with potential as a border for flower beds and ground cover as well as a vegetable. Some authorities include tat soi in the Brassica rapa (Chinensis Group).

Genus name comes from the classical Latin name for cabbage.

Specific epithet means relating to turnips a member of this species.

Problems

Slugs, snails, cutworms, and flea beetles can be a problem.

Garden Uses

Similar in flavor to pak choi, tat soi can be used at all stages: seedling leaves, small rosettes, large plants, and young flowering shoots. Young leaves and small rosettes are used raw in salads and stir fry. Tat soi may also be cooked in soups, sautéed, or added to pasta.