Brassica oleracea Gongylodes Group

RHS Plant Profile

kohlrabi

Other common names

knol-kohl

Annual Biennial

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A biennial plant, mostly grown as an annual vegetable - kohlrabi. This cultivated group has been selected and bred for round, enlarged parts on the pale green or purple stems. Waxy, blueish leaves growing on long stems are also edible when young. The stem enlargement is best harvested when 5-6cm in diameter. It can be eaten raw or cooked. Many different cultivars are available, varying in colour

Position

Full sun

Soil Types

Chalk, Loam, Clay, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 1 year
Max Spread: 0.1-0.5 metres
Max Height: 0.1-0.5 metres

Growing Conditions

Chalk Loam Clay Sand

Moisture: Moist but well–drained
pH: Alkaline or Neutral

Position

Full sun

Aspect: East–facing or South–facing or West–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H4

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Brassicaceae
Native to GB/Ireland: No
Foliage: Semi evergreen
Habit: Columnar upright
Genus: Brassicas can be annual, biennial or perennial plants, most are upright with alternate, often glaucous leaves, long taproots and clusters of cross-shaped, yellow or white flowers. The genus includes a number of species bred to produce food crops, such as cabbages, turnips, mustards and oilseed rape, as well as others grown for their ornamental value
Name Status: Accepted

How to Grow

Cultivation

Sow seed outdoors in deep, fertile but firm, soil that isn't too acidic. If space is limited, start the seeds in modules or seedtrays and plant outside when big enough to handle easily (about 5 or 6 small leaves). Follow kohl-rabi cultivation for more advice

Propagation

Propagate by seed. See sowing vegetable seeds

Pruning

No pruning required

Pests

May be susceptible to flea beetle, cabbage root fly, caterpillars, pigeons and snails, although once plants are established, this damage isn't usually severe. Heavy infestations of mealy cabbage aphid may also spoil the harvest.

Diseases

May be susceptible to brassica downy mildew and brassica white blister. In areas where brassicas have been grown before, club root can build up in the soil