Know your Sea Kale

Know your Sea Kale - Introduction

  • Sea kale, Crambe maritima, is a halophytic perennial plant in the genus Crambe that grows wild along the coasts of Europe, from the North Atlantic to the Black Sea. 
  • Sea kale is more commonly used in Europe and only rarely grown in the United States.
  • Etiolated sprouts are the only edible portion of sea kale.
  • In The Netherlands sea kale is now farmed commercially and finds a ready market.

Know your Sea Kale - Common names

  • Sea kale is also know as Colewort.

Know your Sea Kale - Botany

  • This species is notable in stature, forming a giant mound and producing a profusion of airy white flowers on tall stems in late spring to midsummer and then dying down in midsummer to late summer. 
  • It is a perennial wild plant of the north-west European coast and the Black Sea region. 
  • Morphologically sea kale looks like large foliated cabbage. 
  • The first leaves are purple and successive leaves become greener. 
  • Mature leaves are usually over 30 cm long (and can reach more than 90 cm), long stalked, more or less pinnately lobed with wavy margins. 
  • When the plant is fully grown, it develops 0.8-1.5 cm large white flowers highly visited by bees and , then, 0.75-1.0 cm diameter light silques. 
  • These indehiscent fruits usually contain one seed. 
  • Roots are cylindrical and vigorous and show a capacity for regeneration when divided. 
  • Root cutting is the most efficient propagation method for sea kale.
  • Sea kale can reach 2.5 metres (8 feet) high and about half as wide. 
  • Sea kale is a fully cross-pollinated plant and is self-incompatible. 
  • Genetic variability is large and involves such economic characters as morphology of vegetative and reproductive organs, earliness, and anthocyanin formation in the leaves.
  • Under the climatic conditions of northern France, the development cycle of sea kale is similar to rhubarb. 
    • Sprouts of early spring growth are etiolated and white if they develop without light as in witloof chicory and asparagus
    • Etiolated sprouts are the only edible portion of sea kale.

Know your Sea Kale - Cultivation

  • Sea kale is sometimes grown as an ornamental but its most common use is as a blanched vegetable. 
  • Along the coast of England, where it is commonly found above High Tide Mark on shingle beaches, local people heaped loose shingle around the naturally occurring root crowns in springtime, thus blanching the emerging shoots. 
  • By the early 18th Century it had become established as a garden vegetable, but its height of popularity was the early 19th Century when sea kale appeared in Thomas Jefferson's Garden Book of 1809, and it was served at the Prince Regent's Royal Pavilion in Brighton. 
  • The shoots are served like asparagus: steamed, with either a bechamel sauce or melted butter, salt and pepper. 
  • It is apt to get bruised or damaged in transport and should be eaten very soon after cutting, this may explain its subsequent decline in popularity. 
  • However, given a rich, deep and sandy soil, it is easy to propagate and grow on from root cuttings available from specialist nurseries. 
  • Blanching may be achieved by covering it with opaque material or using a deep, loose and dry mulch.
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