Young shoots of Seakale are eaten as a vegetable. They look very similar to Asparagus. Most people consider them the only part of the plant that is edible, though some people also like the leaves when they are very small and young.
In the wild, the plant grows as a perennial along coastal areas of Europe and the Black Sea. Its leaves start out purple, becoming green. The plant will bloom with attractive clusters of white flowers.
Domestically, Seakale is propagated via cuttings. Newly-planted Seakale is allowed to grow undisturbed for the first year or two. Then, cuttings are taken and planted in the fall. In gardens, they can be treated as a perennial plants. As spring approaches, they are covered with a pot, slate shingles or a light-proof cloche to keep light off of them. The stalks will grow blanched, white shoots, just as Champagne Rhubarb does. In warehouses, the temperature is raised in the spring to induce growth, and the light is kept very low to blanch them.
When growing them in the garden as a perennial vegetable, you harvest just two or three shoots from each plant, then leave the rest to grow so the plant can grow back next year.
Seakale can be eaten raw or boiled or steamed. The white shoots don’t need to be peeled, just washed. Boil for 4 minutes.
Seakale was cultivated in England since at least the time of Queen Anne, if not before. It was very popular at the end of the 1800s and at the beginning of 1900s, but then its popularity died out. It had been grown in the kind of kitchen gardens attached to great homes, and as they died out, so did the popular cultivation of Seakale.
It is experiencing a small re-emergence as a niche food. As of 2014, it is being revived as a salad vegetable in the kitchen gardens at Hampton Court in London. 
Literature & Lore
“Lady Lufton recommended Madeira instead of sherry, and Mr Crawley obeyed at once, and was, indeed, perfectly unconscious of the difference. Then there was a basket of seakale in the gig for Mrs Crawley; that he would have left behind had he dared, but he did not dare. Not a word was said to him as to the marmalade for the children which was hidden under the seakale, Lady Lufton feeling well aware that that would find its way to its proper destination without any necessity for his co-operation. And then Mr Crawley returned home in the Framley Court gig.” — Anthony Trollope, Framley Parsonage, Chapter 15.
“Let all those who have houses and the adjuncts of houses think how considerable a part of their life’s pleasures consists in their interest in the things around them. When will the Seakale be fit to cut, and when will the crocuses come up? ” — Anthony Trollope, Castle Richmond, Chapter 32.
Another name for Seakale is “scurvy grass”, even though that name is also applied to several others. Also spelled “sea kale.”
 Lawrence, Sandra. Royal kitchen gardens bloom once more. London: Daily Telegraph. 4 July 2014.