Common Name: sea holly
Type: Herbaceous perennial
Family: Apiaceae
Zone: 4 to 8
Height: 0.50 to 1.00 feet
Spread: 0.50 to 1.00 feet
Bloom Time: June to September
Bloom Description: Purplish blue
Sun: Full sun
Water: Dry
Maintenance: Low
Flower: Showy
Leaf: Colorful
Other: Thorns
Tolerate: Drought, Dry Soil
Culture
Easily grown in dry, sandy, well-drained soils in full sun. Tolerates poor soils. Tall plants may sprawl, particularly if grown in overly fertile soils or in anything less than full sun. Avoid overwatering. This is a taprooted plant that transplants poorly and is best left undisturbed once established. Plants will slowly spread in the garden over time.
'Blue Hobbit' May be grown from seed. Plants will slowly spread in the garden over time.
Noteworthy Characteristics
Eryngium planum, commonly called sea holly, is a coarse, clump-forming perennial that features a summer bloom of steel-blue, thistle-like flower heads on branched stems rising from a rosette of dark green basal leaves. Basal leaves (typically elliptic to oblong, cordate-based and deeply-toothed) form a rosette to 6" tall and to 14" wide. Stiff, branched, violet-blue stems (to 32” tall), bearing abundant, egg-shaped, thistle-like, violet-blue flower heads, rise from each basal rosette in summer. Each flower head is a spherical-cylindrical umbel that is packed with tiny, stemless, violet-blue flowers. Each flower head is subtended by a narrow, spiky collar of spiny, blue-green bracts. Summer bloom is often profuse.
Genus name comes from an ancient Greek name used by Theophrastus for a plant which grew in Greece (probably Eryngium campestre) or is a Greek reference to the prickly or spiny nature of plants in this genus.
Specific epithet means flat.
‘Blue Hobbit’ is a dwarf sea holly that rises in a globular mound to only 8-12" tall when in full bloom. Spiny, egg-shaped, purplish-blue flower heads atop silver-blue stems appear in a profuse and long summer bloom. Cultivar name of Hobbit is in reference to fictional characters created by J. R. R. Tolkien.
Problems
No serious insect or disease problems. Susceptible to root rot (needs dry soils). Watch for leaf spot diseases. Aphids, slugs and snails may appear.
Uses
Excellent selection for sun baked areas of the landscape. Beds and borders. Effective as a single specimen or in groupings. Excellent for cut or dried flower arrangements.
Good selection for combination containers.