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Eryngium planum (flat sea holly) blooms
Eryngium planum (flat sea holly) in full bloom
Eryngium planum (flat sea holly) dried seed heads
Eryngium planum (flat sea holly) in garden
Eryngium planum (flat sea holly) foliage

flat sea holly

Eryngium planum

Flat Sea Holly is an excellent architectural plant for the dry garden. Blue-tinged stems hold spiky, metallic blue flowers above a rosette of waxy, glaucous foliage. Pollinators adore the unusual flowers!

Dried flowers lend interest to the winter garden and are a boon to the birds.

This plant prefers to grow in poor, sandy soils and will tolerate salt. Staking required if grown in less than full sun or overly fertile soil.

Deer, rabbit, and drought resistant.

Zones: 5 to 9
Family: Apiaceae
Type: Perennial
Height: 24 to 36 in.
Spread: 12 to 24 in.
Exposure: Full Sun
Soil Conditions: dry, well-drained, average
Bloom Time: June to September
Bloom Color: Blue
Native Range: Central and southeastern Europe

Special Characteristics
  • Deer-resistant
  • Salt tolerant
  • Pollinator favorite
  • Winter interest
image credits

Image 1-2 (blooms) Ali McEnhill at The Old Dairy
Image 3 (winter interest) Agnieszka Kwiecień, Nova, CC BY-SA 4.0, via Wikimedia Commons
Image 4 (form) photo taken by User:Nordelch in July 2005, via Wikimedia Commons
Image 5 (foliage) Photo by David J. Stang, CC BY-SA 4.0, via Wikimedia Commons

Regular price
$8.99
Regular price
Sale price
$8.99
Shipping calculated at checkout.

ships spring 2025

PLEASE KNOW: Plants shipped in early spring are likely to arrive dormant.
Eryngium planum (flat sea holly) blooms
Eryngium planum (flat sea holly) in full bloom
Eryngium planum (flat sea holly) dried seed heads
Eryngium planum (flat sea holly) in garden
Eryngium planum (flat sea holly) foliage

Ordering information

Preorders

You may place your order anytime to reserve plants for spring 2025 shipment. If you place multiple orders, we will combine plants into one box (or as many as needed) and any extra shipping charges will be refunded when we ship.

We will begin shipping plants as soon as plants begin to emerge from dormancy in spring. Woodies will likely begin shipping in April. Perennials will likely begin shipping in May. If ordering multiple varieties, we will hold until all plants are ready to ship together. If you would like to receive plants sooner please reach out.

We will check in with you a week before shipping to make sure you receive your plants at a time that is convenient for you.

Shipping

Live plants ship in spring and fall only. Plants may ship dormant, depending on variety and season. Shipping costs are most reasonable when bundling like size plants.

  • 4-inch: 1-6 plants ship for $15.00 / 7-13 plants ship for $18.00 / 14-30 plants ship for $40.00
  • 1-gal: 1-2 plants ship for $18.00 / 3-4 plants ship for $25.00 / 5-6 plants ship for $40.00
  • trees & shrubs: $27.00-$40.00 each, height dependent

We regret that we cannot ship internationally or to the following states: AK, AZ, CA, CO, FL, HI, ID, MT, NV, OR, UT, or WA.

Read more about our shipping policies here.

Nursery pick up

Plants can be collected from the nursery Monday through Sunday from 10am-4pm in Spring, Summer, and Fall. We prefer 24 hour notice to get your order together and will email you when ready for collection.

If you place a SPRING 2025 PREORDER, we will contact you in spring when your plants are ready for collection. Woodies will likely become available for collection in April. Perennials will likely become available in May. If ordering multiple varieties, we will hold until all plants are ready to be collected together.

Plant Sizes

We most commonly use the following pot sizes for perennials:

  • 4-inch pot: 3.5" H x 3.5" W x 3.5" D
  • 2-quart pot: 6" H x 5.25" W x 5.25" D
  • 1-gallon pot: 6.87" H x 8" Dia (this is a true one gallon pot, not the smaller 'trade' one gallon pot used by many nurseries)

Check out our illustrated pot size guide here.

Representative trees & shrubs are photographed in their pots and posted on each plant page.

Sustainability

Sustainability is at the heart of what we do at The Old Dairy. We grow all of our plants outdoors without the use of chemicals, fertilizers, carbon fuels, or peat.

Many of our perennials are grown in the ground and dug upon order (this is especially true for larger sizes). This practice allows us to grow stronger, healthier plants using native soil, and ultimately reduces our impact on the environment.

Our open-pollinated seeds are collected from plants in our mother beds, which have never been treated with chemicals or sprays of any kind.

Read all about our sustainable practices here.

garden location coming soongarden location coming soon
Eryngium planum (flat sea holly) in full bloomEryngium planum (flat sea holly) in full bloom

view this plant in our garden

Eryngium planum | Nursery: Trough Garden 2024

seedling image

Eryngium planum

We are slowly creating a seedling image library to help make weeding easier.
Eryngium planum (flat sea holly) in full bloomEryngium planum (flat sea holly) in full bloom
garden location coming soongarden location coming soon