perennial

Ivory Sea Holly

The Story

Plant Bio

Eryngium eburneum is an evergreen perennial forming a large rosette of sharp, sword-like, green leaves. In summer, it sends up tall, branching flower stalks bearing thistle-like, greenish-white flower heads.

This species is renowned for its dramatic, architectural form and drought tolerance, making it an excellent choice for xeriscaping. Its evergreen rosette provides year-round interest.

Uses & Benefits:

Adds architectural interest with its spiky form and metallic sheen, thriving in drought conditions.

Low water needs and minimal maintenance make it ideal for xeriscaping.

Attracts pollinators like bees and butterflies, supporting local biodiversity.

Essentials

At a Glance

Plant Type

Perennial

Height

48 inches

Width

24 inches

Light

Full Sun, Partial Sun

Zones

7, 8, 9, 10

Water

Low

Humidity

Average

Lifespan

Perennial

Native To

South America

Toxicity

Can cause minor skin irritation; otherwise low toxicity.

Bloom period

Mid-summer – Late summer

In flower about 2 months of the year

Planting

How to Grow

Tuck seeds into well-drained soil in early spring.
Water regularly until established, then reduce watering.
Pinch back to promote bushier growth during early summer.
Apply a balanced fertilizer in spring for best blooms.
Divide in early spring or fall every 3-4 years to maintain vigor.
Mulch lightly to retain moisture and suppress weeds.

Pro Tip

Ensure excellent drainage to prevent root rot and promote healthy growth.

Keep It Thriving

Care Guide

Do

Water sparingly once established 💧
Provide full sun for optimal flowering 🌞
Use well-draining soil to prevent waterlogging 🌱
Deadhead spent flowers to encourage more blooms 🌸
Divide every few years to maintain plant health

Don't

Overwatering can cause root rot ❌
Avoid heavy, clay soils without amendment ❌
Don’t prune in late fall or winter ❌
Don’t fertilize excessively, as it can reduce drought tolerance ❌

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Divide
Harvest
Plant
Prune
Spring Cleanup

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Silver-foliaged borderArchitectural focal pointDrought-tolerant xeriscape

Companion Plants

SedumLavender Russian Sage Yarrow Agastache

Multiply

Propagation Methods

Good to Know

Common Questions

Ivory Sea Holly questions

What zones can Ivory Sea Holly grow in?

Ivory Sea Holly is hardy in USDA Zones 7–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Ivory Sea Holly deer resistant?

Yes — Ivory Sea Holly is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

When does Ivory Sea Holly bloom?

Ivory Sea Holly typically blooms in mid-summer through late summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Ivory Sea Holly need full sun?

Ivory Sea Holly does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Is Ivory Sea Holly drought tolerant?

Yes — once established (usually after the first full season), Ivory Sea Holly handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.