Eryngium – Sea Holly, Ivory Thistle
This is a prickly plant in every feature-the leaves are prickly, the flower heads are surrounded by spreading, prickly floral bracts and the flower head itself is like a small Teazle. The beauty of this plant depends upon the blue-gray effect which it presents. They grow to a height of 3 feet and bloom from June to September.
Eryngium amethystinum has amethyst-colored flowers and grows at least 9. feet tall. E. planum has numerous small flower heads and shining stems. E. maritimum has whitish or pale blue flowers and grows 1 foot tall. E. Olberianum grows 3 feet tall and has large flower heads of deep blue flowers.
UTILIZE. The Eryngium is most effective when massed on the lawn, and its uses as a cut flower are many. It is very decorative for basket work, or combined in vases with Gladioli. The branches can be dried, so that the flowers are used in Winter bouquets. The plants are used in wild gardens or grouped with the shrubbery.
GENERAL. Eryngiums thrive best in full sun, in light, sandy loam. They withstand dry seasons well and when once established should not be moved often.
PROPAGATION. They are raised from seeds, but some have found that certain of the sorts are rather capricious although the plants frequently self-sow their seeds and spread rapidly. Sow the seed as soon as ripe, in which case they germinate the next Spring. The plants are divided with difficulty.