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2024 Seed Catalog

Sea holly Blue Cap - Eryngium planum


Blue Cap

Sea Holly Seeds

Blue Cap sea holly is easy to grow. Iridescent bright blue, spiny, thistle-like flowers July to September. Superb cut flowers, fresh or dried. Grows to 3 ft. tall. Winter hardy to zone 5. Combines nicely with Gay Butterflies butterfly weed, Primadonna White echinacea, and Giant Yellow Herold foxglove.

40 seeds - $3.49
View all of our Sea Holly varieties.

Growing Blue Cap Sea Holly Seeds

Bee introduces how to plant

Plant Sea Holly Seeds: Sow seeds in 2 in. pots or cell packs, press into soil and barely cover. Needs light to germinate. Kept at 70° F., germination usually within 4 weeks. If not, put container inside a zip-lock bag and place in the refrigerator for 4 weeks. Return to 70° F. until germination occurs. Transplant Sea Holly 18-24 in. apart. See starting your seeds, for information on growing seedlings under lights.

Grow Sea Holly: Full sun. Sea Holly plants tolerate heat, drought, humidity and salt and prefer deep, sandy soils. Will tolerate any soil as long as drainage is good. Water weekly during hottest weather for best performance. Cut flowers are long lasting, fresh or dried. The intense blue color of the flowers are intensified by warm days, followed by cool nights. Flowers attract bees, hummingbirds and butterflies.

Shipping Information

U.S. Shipping Rates

Free shipping on U.S. orders over $60.00.
Free priority shipping on U.S. orders over $150.00.

Standard U.S. shipping is $5.99.
Priority U.S. shipping is $9.99.

International Shipping Rates

Shipping to Canada is $13.99.
International shipping to all other countries is $15.99.

Satisfaction Guarantee

We guarantee all the seeds we sell for one full year from the date of purchase. If you are unsatisfied with any seeds purchased from Swallowtail Garden Seeds, we will issue a refund. For customers in the U.S., we can send one-time replacements or issue a refund.