Colorado Master Gardeners: Something totally different — sea holly
My introduction to Eryngium (pronounced “iˈrinjēəm,” and Greek for “prickly plant”) was at a friend’s garden party earlier this summer. I saw it again a few weeks later in the garden at Eagle’s CSU Extension Office and again at Betty Ford Alpine Gardens. It makes me wonder how I missed this striking plant until now.
A description of the plant I have been noticing (E. planum) doesn’t do it justice. It resembles a thistle with its thorny stems and leaves, but it’s the unusual blue color of the stems and flowers that makes the plant so eye-catching.
The common name, sea holly, is confusing, as well, as it describes E. maritimum’s preference for a coastal environment and holly-like leaves. It is not a holly (genus Ilex, family Aquifoliaceae). Rather, it is member of the Apiaceae family, which includes carrots, parsley and dill.
The more than 230 species in the genus Eryngium are mostly tall, prickly, drought-tolerant perennials that bloom in a variety of colors, including bright blue, purple, greenish-white and even tan.
Another common name is “eryngo,” and some species have other unusual characteristics. For example, most of the entire plant of a variety grown in Texas (E. leavenworthii ) is purple. Another (E. yuccifolium) is called rattlesnake master and looks more similar to a yucca plant. Its root was used by some Native Americans to treat rattlesnake bites. E. gigantium has the common name of “Miss Wilmott’s Ghost,” named for British gardener, Ellen Wilmott, and a story about her scattering seeds in “uninteresting” gardens. “Miss Wilmott’s Ghost,” would sprout after her visits.
Through further research, I learned the blue plants I saw this summer were varieties of E. planum, which grow 2- to 3-feet-tall and 1- to 2-feet-wide. They flower in July and August.
Plants may be grown from seed but may not bloom until the second year. E. alpinum may be a better choice for our area (zones 2 through 8) but may be more difficult to start or find at a nursery. Most varieties are perennial, but there are biennials and annuals, too. The plant originated in the Middle East and grows throughout most of the world. E. yuccifolium is considered a native to the tallgrass prairies of central and eastern North America. E leavenworthii, an annual, is a wildflower in Texas.
Sea holly is popular in European gardens (thanks, in part, to Miss Wilmott) and is a good choice for our Routt County gardens. Once established, it is xeric, preferring dry, well-drained soil and lots of sun. Some varieties can tolerate light shade, however the intensity of the color increases in proportion to the amount of sunlight it receives.
Suggested companion plants include Russian sages and lavender, as well as tall yellow foxgloves and hollyhocks.
Though not native to our area, sea holly is attractive to butterflies and other beneficial insects and is deer and rabbit resistant, as well. It grows by a deep taproot and does not tolerate transplanting, and it will spread by seed but is not considered invasive. The hardest part of growing sea holly may be finding the sunniest, most visible spot in the garden for this striking plant.
Longtime Steamboat Springs resident and casual gardener Vicky Barney is a member of the Master Gardener Class of 2011.
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