Sea holly (Eryngium) is a spiky, stiffly branched, architectural plant, perhaps best given space to make its own statement, ideally in a gravel garden. It will also integrate in mixed, sunny borders, providing an excellent contrast to softer plants. If you are growing a blue sea holly plant in containers, place them with other plants that can tolerate dry conditions. Some of them are biennials. This striking plant has deeply cut, bluish-grey leaves, veined white, and spiky steel-blue cones of flowers. Cultivars, which vary in height and the exact shade of blue, include ‘Blue Glitter’, ‘Sapphire Blue’ and ‘Big Blue’.
Sea holly should be grown in full sun and in light, well draining soil. Sea holly does not like to be disturbed so choose a spot where it will not need transplanting.
The plant produces a long tap root which makes transplanting or division difficult, but also serves to make it a very drought tolerant plant. Sea hollies have an upright growth habit from two to six feet, depending on the variety, and flower repeatedly from midsummer into fall.
During the first year, sea holly needs more specialized care than it will in subsequent growing seasons. Once the soil has warmed in the spring, direct seed it into your garden bed or container or use young plants from the nursery. Water well after planting and mulch the area to retain moisture. In its second and subsequent years, the sea holly does not require weekly watering. In fact, take special care not to over-water the plants. Once established, the sea holly is tolerant of dry soils.
Sea holly fits well with plants from arid regions, making it suitable for desert, Southwestern or Mediterranean themed landscapes. Surround it with succulents and other species that are known for their foliage as much as their flowers.
This ornamental plant looks beautiful in flower arrangements – both fresh and dried. For dried use, cut stems just as the first few flowers in each umbel are almost fully opened: hang upside down in a dark, warm room to dry.
Eryngium ‘Silver Ghost’