
Light Needs

Mature Height

Mature Spread

Growing Zones
Big Blue Sea Holly, Star Thistle, Blue Sea Holly, or Eryngium x zabelii ‘Big Blue’, is a stunning, low-maintenance perennial, known for its vivid, color-changing foliage. This remarkable Sea Holly produces spiny, basal clumps of silvery-green foliage that unfurls in late spring with thick thistle-like buds. In late summer to early fall, the buds, spiky foliage, and stiff stems take on a purple to bluish tint that deepens and spreads in color as the season progresses, eventually lending these unique plants their vivid color and brushed metallic sheen. Big Blue Sea Holly ranges in height from 24 to 30 inches with an equal spread.
Native to southeastern and central Asia, Big Blue Sea Holly has a stiff, upright growing habit and is relatively drought and salt tolerant, especially once the plant is established, and makes a great coastal option. It is a low-maintenance, easy-to-grow option that is deer and rabbit resistant and attracts both butterflies and critical pollinators. It’s used by florists and gardeners alike to provide a unique and colorful flair to arrangements and bouquets, and makes an excellent dried flower option.
Big Blue Sea Holly Care
Big Blue Sea Holly should be grown in full sun and is very tolerant of hot and dry climates and locations. It can be planted in soil that is dry, sandy and well-drained, slightly acidic to slightly alkaline, and has a pH of 6.0 to 7.8. Sea Holly has deep taproots, which make them difficult to move, so make certain you choose an ideal location before planting. The good news is that this means your Big Blue Sea Holly is drought tolerant. Make certain your Sea Holly has adequate soil drainage. Sea Holly will bloom for a longer period if you deadhead the spent blooms. In late fall or early spring, prune the plants at ground level.
Big Blue Sea Holly Spacing
Big Blue Sea Holly is an excellent option to bring structure and interest to the back of any garden. It should be spaced 2 to 3 inches apart at planting. They look excellent planted alongside coneflower, which can lend them support when they grow tall.
Big Blue Sea Holly Information
USDA Hardiness Zones: 5 - 8 |
Plant Type: Perennials |
Light Exposure: Full Sun (At Least 6 Hours Of Direct Sunlight) |
Mature Height: 24 - 30 Inches |
Mature Spread: 24 - 30 Inches |
Spacing: 24 - 30 Inches |
Habit: Upright |
Flower Color(s): Blue |
Flower Description: |
Bloom Period: July |
Foliage Type: Herbaceous |
Foliage Color(s): Blue, Green, Silver |
Foliage Description: Silvery-Blue. Green |
Seasonal Interest: Summer Flowering |
Watering: Average |
Resists: Deer |
Tolerates: Drought |
Attracts: Bees, Butterflies |
Container Role: |
Uses: Containers, Wildlife Gardens |
Features: Attracts Pollinators, Cut Flowers, Low Maintenance |
Brand: |
Common Name: Big Blue Sea Holly |
Other Name(s): |
Scientific Name: ERYNGIUM `BIG BLUE` |
- SKU:
- 1231011894-pc
Please Note: The pictures below are to give a general representation of the different container sizes. The actual size/ages of plants are estimates and will vary based on type of plant, time of year, last pruning & many other factors.

Also Known As:
Quart
Plant Age:
~ 6 months - 1 year
Plant Size:
~ 4"-8"
Pot Size:
~ 4.75"H x 4.5"W
Volume:
1.50 quarts

Also Known As:
2.5 Quart Pot
Plant Age:
~ 1 - 2 years old
Plant Size:
~ 8"-12"
Pot Size:
~ 6.5"H x 6.5"W
Volume:
2.20-2.30 quarts

Also Known As:
#1 Container
1 Gallon
Plant Age:
~ 1 - 2 years old
Plant Size:
~ 10"-14"
Pot Size:
~ 7"H x 7.75"W
Volume:
2.26-3.73 quarts

Also Known As:
#2 Container
2 Gallon
Plant Age:
~ 1.5 - 3 years old
Plant Size:
~ 12"-18"
Pot Size:
~ 9.5"H x 9.5"W
Volume:
1.19-1.76 gallons

Also Known As:
#3 Container
3 Gallon
Plant Age:
~ 2 - 4 years old
Plant Size:
~ 12"-30"
Pot Size:
~9.5"H x 11"W
Volume:
2.32-2.76 gallons

Also Known As:
#5 Container
5 Gallon
Plant Age:
~3-4 years old
Plant Size:
~ 20" - 60"
Pot Size:
~11" H x 10 1/2” W
Volume:
3.5 - 4 gallons

We stand behind our plants with industry-leading guarantees to give you peace of mind.
We want your plants to arrive in great condition! If you notice any issues upon delivery, contact us within 3 days.
Starting January 1, 2025 all bushes, perennials & trees purchased come with an extended 1-year warranty for added confidence. If your plant dies due to a health issue within a year, we’ll make it right.

Pre-ordered plants are scheduled to ship in Spring 2025. We carefully plan our shipping dates based on your USDA Plant Hardiness Zone to ensure optimal planting conditions upon arrival. Want it sooner/later? Reach out, and we'll try our best to accommodate.
Estimated ship week for pre-ordered plants will ship based on growing zones as shown below.
Growing Zone | Estimated Ship Week |
---|---|
Zone 10 | March 31th |
Zone 9 | March 31st |
Zone 8 | April 7th |
Zone 7 | April 14th |
Zone 6b | April 21st |
Zone 6a | April 28th |
Zone 5b | May 5th |
Zone 5a | May 12th |
Zone 4 | May 19th |
Zone 3 | May 26th |
Note: These are only estimated ship dates. Plants may ship out later depending on weather & growing conditions of the plant.
Note: Only plants indicated as pre-order will ship as shown above. All other plants and hard goods will ship as normal.
Plants that are currently in stock typically ship within 2-7 business days after your order is placed.
Plant Addicts ships to the lower 48 states within the U.S. Unfortunately, we do not currently ship to Alaska, Hawaii, or internationally.
This plant cannot be shipped to the following states: Idaho, AK, HI. These restrictions apply only to this specific plant due to agricultural regulations or other limitations. Other plants may still be available for shipping to these states.
If you have any questions about shipping restrictions, feel free to reach out to our team!