Sea Holly Eryngium × zabelii 'Blue Waves'

👤 Non-toxic to humans
🐾 Non-toxic to pets
🌸 Blooming
🍪 Not edible
‍🌱 Easy-care
sea holly 'Blue Waves'


The 'Blue Waves' is an ornamental plant known for its striking appearance, characterized by its rosettes of spiky, lance-shaped leaves which possess a silver to bluish-green hue. The foliage creates a textural contrast in the garden, giving it a somewhat thorny look, while remaining quite alluring. This plant is visually dominated by its prominent, cone-shaped flower heads that are surrounded by spiky, ruffled bracts. The flowers are typically a metallic blue or steely color, making them highly attractive to gardeners for their unique shade and iridescence. The blooms sit atop sturdy, branched stems that are also silver to bluish-green, contributing further to the plant’s visual impact. 'Blue Waves' can be appreciated for its distinctive form and coloration, which makes it a popular choice for adding structure and interest to garden beds and borders.

Plant Info
Common Problems

About this plant

  • memoNames

    • Family


    • Synonyms

      Blue Glitter Sea Holly

    • Common names

      Eryngium × zabelii 'Blue Waves'.

  • skullToxicity

    • To humans

      Sea Holly, specifically the Eryngium × zabelii 'Blue Waves', is not commonly known to be toxic to humans. There are no well-documented cases of poisoning or significant adverse effects from ingesting this plant. However, as a general precaution, it is not advisable to eat ornamental plants due to potential individual allergies or unknown reactions.

    • To pets

      Sea Holly, namely the Eryngium × zabelii 'Blue Waves', is not known to be toxic to pets such as dogs and cats. There are no widespread reports of poisoning or severe health problems from pets ingesting this plant. Nevertheless, pets might experience mild stomach upset if they consume large amounts of any non-food plants, so it is still best to prevent them from eating ornamental plants.

  • infoCharacteristics

    • Life cycle


    • Foliage type


    • Color of leaves


    • Flower color


    • Height

      2 feet (0.61 meters)

    • Spread

      1 foot (0.30 meters)

    • Plant type


    • Hardiness zones


    • Native area



  • money-bagGeneral Benefits

    • Attracts pollinators: Eryngium × zabelii 'Blue Waves' is known to attract bees, butterflies, and other beneficial insects to your garden.
    • Drought tolerance: Once established, it has good resistance to drought, making it suitable for xeriscaping and water-wise gardens.
    • Low maintenance: This plant requires minimal care and does not need frequent watering, pruning, or fertilization once established.
    • Deer resistance: It is not favored by deer, which helps prevent it from being eaten in areas where deer browsing is a problem.
    • Architectural interest: With its spiky foliage and striking blue flowers, it adds a unique texture and shape to garden landscapes.
    • Long flowering season: The 'Blue Waves' cultivar offers a long bloom time from mid to late summer, providing visual interest for an extended period.
    • Winter interest: The plant's seed heads and structure can add interest to a winter garden after the flowering season is over.

  • medicalMedical Properties

    This plant is not used for medical purposes.

  • windAir-purifying Qualities

    This plant is not specifically known for air purifying qualities.

  • leavesOther Uses

    • Eryngium 'Blue Waves' can be utilized in dried flower arrangements. Its striking blue blooms retain much of their color and shape when dried, making them an excellent choice for long-lasting displays.
    • The plant's architectural structure can serve as natural art in a minimalist garden design, adding both texture and a splash of color without the need for additional garden ornaments.
    • Eryngium 'Blue Waves' can be used as a living barrier in gardens due to its spiky texture, deterring animals and people from venturing into private areas.
    • It may be included in sensory gardens for its unique tactile feel. Children and adults alike are intrigued by the spiny bracts and stems.
    • In coastal areas, Eryngium 'Blue Waves' can be used for landscaping as it tolerates salt and sandy soils well.
    • The striking blue flowers can be used as a natural dye for fabrics or in crafts, providing a sustainable source of color.
    • The plant's resilience to drought makes it an ideal candidate for xeriscaping, contributing to water conservation in garden design.
    • Its inclusion in a moon garden can be quite effective due to the silver to blue-toned foliage that can reflect moonlight and create a luminous night-time display.
    • Eryngium 'Blue Waves' can be planted to attract beneficial insects like bees and butterflies, enhancing local biodiversity.
    • The rigid stems and spiny leaves can be used in art projects or as natural crafting materials for making eco-friendly home decorations.

Interesting Facts

  • bedFeng Shui

    The Sea Holly is not used in Feng Shui practice.

  • aquariusZodiac Sign Compitability

    The Sea Holly is not used in astrology practice.

  • spiralPlant Symbolism

    • Determination: Eryngium plants, also known as Sea Holly, are often associated with persistence and the ability to thrive in challenging conditions, reflecting determination.
    • Independence: With its striking appearance and ability to stand out amongst other plants, Sea Holly can symbolize individuality and the courage to be unique.
    • Protection: The spiny leaves and bracts of the Sea Holly can represent defense and protection, symbolizing a guarding nature against adversity.
    • Attraction: The vibrant blue color and unique texture of Sea Holly can be seen as a symbol of attraction and fascination, often used in floral arrangements to add an eye-catching element.

Every 1-2 weeks
2500 - 10000 Lux
Every 3-4 years
Late spring to early summer
As needed
  • water dropWater

    Sea Holly 'Blue Waves' thrives when the soil is kept evenly moist, especially during its first growing season to establish a deep root system. Once established, it is quite drought-tolerant and requires less frequent watering. A general guideline is to water this plant once a week with about 1-2 gallons of water, making sure to soak the soil thoroughly. During periods of high heat or extended drought, increase watering frequency to ensure the plant does not become overly dry, but always check the soil moisture before doing so to prevent overwatering.

  • sunLight

    Sea Holly 'Blue Waves' prefers full sun to grow and flower best. It should be placed in a location where it receives at least six hours of direct sunlight per day. This plant can tolerate partial shade but will produce fewer blooms and have a less vibrant color. The brightest spot in a garden that offers direct sun exposure is ideal for the health and vigor of 'Blue Waves.'

  • thermometerTemperature

    Sea Holly 'Blue Waves' is adaptable to a wide range of temperatures but ideally prefers conditions between 60°F and 75°F. It can tolerate temperatures as low as 0°F, making it quite hardy, and can survive in high temperatures well into the upper 80s°F. However, the plant will thrive in moderate conditions and should be protected from extreme hot or cold temperatures to maintain its health and vigor.

  • scissorsPruning

    Pruning Sea Holly 'Blue Waves' helps to maintain its appearance and health by removing spent flower stalks and any damaged or dead foliage. Pruning is best done just after flowering, which generally means late summer or early fall. This timing allows the plant to redirect energy into root and foliage development. It's important not to over-prune, as the plant benefits from the foliage for photosynthesis throughout the growing season.

  • broomCleaning

    Not needed

  • bambooSoil

    Sea Holly 'Blue Waves' thrives best in well-draining soil with gravel or sand for added drainage, a soil mix composed of equal parts garden soil, compost, sand, and peat is ideal. The pH should be neutral to slightly alkaline, between 6.0 and 7.5.

  • plantRepotting

    Sea Holly 'Blue Waves' has a deep taproot system and prefers to not be disturbed, so repotting is rarely needed. If necessary, do it sparingly, only when the plant has outgrown its current pot, typically every 3-5 years.

  • water dropsHumidity & Misting

    Sea Holly 'Blue Waves' is tolerant of dry air and does not require high humidity. It is well-adapted to outdoor conditions and typical household humidity levels are generally sufficient for this plant.

  • pinSuitable locations

    • Indoor

      Place in bright light, avoid overwatering, low maintenance.

    • Outdoor

      Full sun, well-drained soil, drought-tolerant once established.

    • Hardiness zone

      5-9 USDA

  • circleLife cycle

    'Blue Waves' Sea Holly, Eryngium × zabelii 'Blue Waves', begins its life cycle as a seed, which germinates in spring to develop a rosette of basal leaves. As the plant matures, it sends up a flowering stem in early to mid-summer, showcasing its distinctive bristly blue flowers that attract pollinators like bees and butterflies. After pollination, these flowers produce seeds that mature by late summer or early fall. The plant then enters a phase of dormancy during the winter with the aerial parts dying back, while the root system remains alive underground. As the following spring arrives, 'Blue Waves' Sea Holly emerges again from its roots, repeating the cycle. The plant can also spread through division of its root system, allowing it to multiply and maintain its presence in a garden.

  • sproutPropogation

    • Propogation time

      Late spring to early summer

    • Eryngium × zabelii 'Blue Waves', commonly known as Sea Holly, can be propagated most effectively by seed. Sow the seeds in late winter to early spring indoors in a flat or pots, using a well-draining seed starting mix. Cover them lightly with the mix, as they need light to germinate. Keep the soil moist, but not waterlogged, and maintain a temperature around 70 degrees Fahrenheit (21 degrees Celsius). Germination can take anywhere from two to six weeks. Once seedlings have developed true leaves and there's no risk of frost, they can be hardened off and transplanted to a sunny location with well-draining soil. Seedling vigor and the resulting plants' consistency may vary since 'Blue Waves' is a hybrid, and seed-propagated plants may not always come true to the parent's characteristics.