Blue Sea Holly (Eryngium planum)
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Deciduous Perennial Upright, Branched in the Apiaceae Family
 
Buy Blue Sea Holly
Size Notes Price Availability
50 plug flat Field

Grower approved but probably not garden center ready. (9/13)

 $155.00 Likely available
11/1 - 11/8
1/24 - 4/4

A tall, airy sea holly with branched, silvery-blue stems and steel-blue flower heads, native from central Europe to Mongolia and tough as nails in a sunny border.

Eryngium planum, commonly called blue sea holly or flat sea holly, is a thistle-like perennial native to a wide swath of central and southeastern Europe through to Mongolia and the western Himalayas. It forms a basal rosette of spiny, white-veined green leaves, from which branched, silvery-blue stems rise in summer, topped with small, cone-shaped flower heads of steel blue to violet-blue, each ringed by spiky blue-green bracts.

It thrives in lean, well-drained sandy or loamy soil in full sun, where more sun intensifies the flower color, and is a reliable, long-blooming choice for a dry border or cutting garden.

Pros

  • Long summer-to-fall bloom of steel-blue flower heads on branched, silvery-blue stems
  • Thrives in dry, poor soil where many perennials struggle
  • Deer- and rabbit-resistant, and tolerant of salty coastal wind
  • Excellent as a cut or dried flower

Cons

  • Taprooted and transplants poorly once established
  • Can grow leggy and topple over in overly rich soil
  • Spiny foliage and bracts make handling uncomfortable
  • May self-seed modestly around the garden
Why Like Native across a vast range from central Europe to Mongolia and the western Himalayas, this species has evolved to handle lean, dry, exposed sites that few other perennials tolerate — a genuinely tough plant for difficult American gardens. Its long bloom season makes it an unusually reliable pollinator plant for a dry-soil specialist.
Highlights The silvery-blue cast of its branched flower stems, combined with dense, upright clusters of small steel-blue flower heads, gives this species a finer, airier texture than many of its Eryngium relatives. It's also one of the more reliably floriferous sea hollies, blooming steadily from early summer well into fall and drawing a steady stream of bees, butterflies, and other pollinators.
 

Plant Data

Mature Size 24 - 36 inches tall. 12 - 24 inches wide.
Sun Exposure Full Sun - Full Sun
Moisture Tolerance Dry
Zones 5a - 9b (Usually hardy to -20° F)
Tags Attracts Bees, Attracts Butterflies, Attracts Pollinators, Deciduous, Deer Resistant, Drought Tolerant, Dry, Dry, Full Sun, Full Sun, Good for Borders, Low Maintenance, Native to Asia, Native to Europe, Non-Allergenic, Perennial, Rabbit Resistant, Showy Flowers, Tolerant of Hot Dry Site, Tolerant of Poor Soil, Tolerant of Salt, Tolerant of Sandy Soil, Well-Drained Soil
Bloom Period Summer To Fall
Flower Color Steel Blue To Violet-Blue
 

More Info from Experts
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Pricing and Availability History

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Past Availability
2024 : 07/02 - 09/08
2023 : 06/21 - 09/10


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Field-Grown vs. Greenhouse-Grown Plants

Plants which are well-adapted to our local climate are most often field-grown (outside). Field-grown plants are generally cheaper and have the advantage of already somewhat acclimated to our cold winters, but that means they’re not artificially far along in the spring and tend to bloom at the normal time in our area.

Spring annuals and tender perennials are typically grown in Greenhouses so they can be ready and luxurious exactly when customers want them. Some perennials are also “forced” into early bloom in greenhouses. In May, there can be a very big difference between field-grown and greenhouse-grown plants of the same type. The latter typically look good right away (so they’re a great choice where that’s important), but we typically pay a premium for it.


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No Pricing or Availability Right Now

We order from a rotating cast of the best nurseries in the Great Lakes region. It looks like we've offered this plant in the past, but the nurseries we're working with this week don't appear to have it in stock at the moment.

Our goal is to bring as many plants together under "one roof" as possible, so we'll try hard to make it available again in the future!