Plant of the Month July 2025
This is a low-maintenance biennial from the Middle East. Legend has it that Miss Willmott, (Ellen Willmott, 1858-1934) loved the plant and surupticiuosly dropped seeds in appropriate places when she visited gardens. Another Giant Sea Holly, Eryngium pandanifolium, is native to South America.
GENERAL INFORMATION:
Common Name: Miss Wilmots Ghost, Giant Sea Holly, Giant Ornamental Thistle Flower, Tall Eryngo.
Eryngium giganteum, inforescence.
Cultivars: ‘Silver Ghost’.
Life Cycle: Herbaceous biennial. Most Eryngium sp. are perennial.
Height: 60-100cm, about 100cm wide.
Bloom Time: June to August.
Flower Colour & Size: Tight cone-shaped umbel of small greenish blue flowers with blue anthers, surrounded by silvery, spiky, palmately divided, 7cm bracts.
Eryngium giganteum, with pollinator (Digger wasp, Sphex ichneumoneus).
Leaves: A basal evergreen rosette of 15cm long, heart shaped green leaves, forms during the first year. The leaves wither as the flower stalk appears.
Range: Native to Turkey, Caucuses, Iran .
Habitat: Tall grass prairies and dry, well-drained soils.
CULTIVATION:
Plant: in a suitable place when small. The tap-rooted plant resents disturbance.
Light: Full sun.
Soil: Most soils - prefers moist, well drained fertile soil.
Water: Medium. Drought tolerant.
USDA Hardiness: Zones 4-7.
Companion planting: Other sun loving perennials.
Problems: Nothing serious.
Eryngium giganteum, maturing seed (fruit) heads.
Propagation: Will self-seed. Sow @ 20°C for 6 weeks, then 4°C for 6 weeks, slowly raise temperature to 10°C for 6 weeks. If there is no germination, repeat the cycle.
Eryngium giganteum, seed dispersal.
Pollinators: Bees, butterflies, hover flies.
References:
https://www.missouribotanicalgarden.org/PlantFinder
https://onrockgarden.com/index.php/germination-guide
Text and images supplied by Anna Leggatt (Toronto Master Gardener)