Crambe maritima, or Sea kale, is a perennial type of plant that grows in Ireland, the beaches of northern Europe, and along the Baltic and Black seas. It grows in coarsely grained sand and gravelly beaches just past the high tide level. A protected species, sea kale is considered a type of cabbage plant and has thick, wavy leaves that can tolerate a great deal of salt exposure and wind. The leaves are blue and green and coated in wax that protects them from the elements, and white flowers can appear on the plant in the summer. Seeds are formed inside pods that can be transported to other places in the water.
Sea kale can be grown as a vegetable in a garden, although the practice is rare. Growing this type kale is not that difficult because the seeds will grow in a mixture of soil and sand in a pot. The seeds will also germinate relatively quickly in sunny areas and yield perennial plants that can last for up to a few decades. It is custom to blanch the leaves before eating them. Otherwise, they would be hard to chew and too bitter to eat, but in raw form they are a source of Vitamin C.
In gardens, sea kale is sometimes used to contrast the color of brighter colored flowers, especially ones that are orange and white. The leaves will shed and rot in the winter, and it is important to cover the plants. They can be moved to a heated location or covered by a container that does not allow light to pass through. This can force development so that the plants will be ready for development earlier in the spring. Maintenance also includes cutting stems on the kale for it to grow younger shoots.
Caterpillars and slugs are the only pests that can threaten sea kale. The plant grows best when it is used with mulching material that includes manure. Rare among the many classes of vegetables that are grown and traded worldwide, it is not commercially sold for food anywhere in the world except in Britain and France. Sea kale must grow for three years before it can be harvested and eaten, and the leaves taste similar to cabbage. The shoots have a taste similar to asparagus and cauliflower, so this plant can be a viable addition to a salad.