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BRASSICA rapa (Chinensis Group)

Image of Brassica rapa (Chinensis Group)

Gerald L. Klingaman

Family

Brassicaceae

Botanical Name

BRASSICA rapa( Chinensis Group)

Plant Common Name

Bok Choy, Chinese Cabbage, Choy Sum, Pak Choi

General Description

Characterized by chard-like clusters of leaves with thick, white to pale green leaf stalks, the Chinensis group of brassicas includes pak choi, bok choy and Chinese and Japanese cabbage. It is one of several groups within Brassica rapa, which is Eurasian in origin but is now cultivated worldwide. All in the Chinensis group were selected from different regions of Asia and many cultivars exist.

These annual or biennial, cool season plants form loose rosettes of upright green leaves with white stalks and midribs. Numerous varieties are available, differing in the size (calf- to knee-high), foliage color (dark green, yellow or purple) and texture (smooth or frilly). All grow best in cool weather, though some are relatively heat-tolerant. 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.

These cool weather crops prefer full sun and moderately fertile, humus-rich, slightly acid soil with ample drainage. They generally mature quickly, from 30 to 80 days, depending on variety. Sow them in early spring before temperatures heat up or in late summer for fall harvest. In areas with mild climates these frost-hardy veggies make an excellent winter crop. Hot weather will cause them to flower ("bolt"), which usually results in bitter-tasting, dwindling plants.

These brassicas 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. The delicious, variable greens are generally easy to grow and very tasty if harvested when temperatures are cool. Use the young leaves in salads and the mature leaves and stems for steaming or stir-frying.

Characteristics

  • AHS Heat Zone

    9 - 3

  • USDA Hardiness Zone

    6 - 11

  • Sunset Zone

    A1, A2, A3, H1, H2, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type

    Vegetable

  • Sun Exposure

    Full Sun, Partial Sun

  • Height

    6"-36" / 15.2cm - 91.4cm

  • Width

    6"-24" / 15.2cm - 61.0cm

  • Bloom Time

    Spring, Summer

  • Native To

    Europe

Growing Conditions

  • Soil pH

    Acidic, Neutral

  • Soil Drainage

    Well Drained

  • Soil type

    Clay, Loam, Sand

  • Growth Rate

    Fast

  • Water Requirements

    Average Water

  • Habit

    Upright/Erect

  • Seasonal Interest

    Spring, Fall, Winter

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    Yellow

  • Fruit Color

    Sienna, Black

  • Foliage Color (Spring)

    White, Green, Dark Green

  • Foliage Color (Summer)

    White, Green, Dark Green

  • Foliage Color (Fall)

    White, Green, Dark Green

  • Foliage Color (Winter)

    White, Green, Dark Green

  • Fragrant Flowers

    No

  • Fragrant Fruit

    No

  • Fragrant Foliage

    Yes

  • Bark or Stem Fragrant

    No

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    No

  • Edible Fruit

    No

  • Showy Foliage

    Yes

  • Foliage Texture

    Medium

  • Evergreen

    No

  • Showy Bark

    No

Special Characteristics

  • Usage

    Container, Edible, Herb / Vegetable, Wildflower

  • Sharp or Has Thorns

    No

  • Invasive

    Sometimes

  • Attracts

    Butterflies

  • Self-Sowing

    Yes