Yellow Flag Iris Iris 'Sulphureux'

☠ Toxic to humans
🐾 Toxic to pets
🌸 Blooming
🍪 Not edible
‍🌱 Easy-care
iris 'Sulphureux'


Iris 'Sulphureux' is a captivating plant with a visually striking appearance. This plant is part of the bearded iris group, identifiable by its unique flower structure. The plant features beautiful blooms that are primarily a light, creamy yellow hue, which is where it gets its name resembling sulphur. Each flower possesses three upright petals known as standards, accompanied by three downward-curving petals called falls. The falls often showcase a slightly deeper yellow tint and may exhibit a delicate veining or a subtle gradation of color. In the center of the falls is a fuzzy strip, commonly referred to as the "beard," which typically echoes the bloom's overall color palette in a more saturated tone. The foliage of the Iris 'Sulphureux' consists of long, slender leaves that grow with a slight arch. These leaves are a bright green color, which contrasts beautifully with the soft yellow of the flowers, creating an eye-catching display in any garden setting. The leaves emerge from sturdy, upright stems that rise from the base of the plant, forming a fan-like arrangement that serves as an elegant backdrop for the showy blooms.

Plant Info
Common Problems

About this plant

  • memoNames

    • Family


    • Synonyms

      Sulphureux Iris, Pale Yellow Iris

    • Common names

      Iris 'Sulphureux'.

  • skullToxicity

    • To humans

      The Yellow Iris, also known by its cultivar name 'Sulphureux', can be toxic to humans if ingested. The plant contains compounds such as irisin, iridin, or irisine which can cause symptoms including stomach pain, nausea, vomiting, and diarrhea. In severe cases, ingestion could lead to more serious issues like damage to the liver or kidneys. It is best to avoid consuming any part of this plant.

    • To pets

      The Yellow Iris, also known as 'Sulphureux', is toxic to pets if ingested. The plant's rhizomes and bulbs contain irisin, iridin, or irisine, which can cause gastrointestinal upset in pets such as vomiting, diarrhea, or excessive salivation. In severe cases, ingestion could potentially cause abdominal pain, lethargy, or even liver or kidney damage. It is important to prevent pets from eating any part of this plant.

  • infoCharacteristics

    • Life cycle


    • Foliage type


    • Color of leaves


    • Flower color


    • Height

      2-3 feet (0.6-0.9 meters)

    • Spread

      1-2 feet (0.3-0.6 meters)

    • Plant type


    • Hardiness zones


    • Native area



  • money-bagGeneral Benefits

    • Aesthetic Appeal: Iris 'Sulphureux', commonly known as Yellow Flag Iris, has vibrant yellow flowers that enhance the visual appeal of gardens and landscapes.
    • Pollinator Attraction: The flowers attract pollinators, such as bees and butterflies, which is crucial for the health of the ecosystem.
    • Erosion Control: The dense root system of the Iris 'Sulphureux' helps to stabilize soil and prevent erosion, especially in wet areas.
    • Water Quality Improvement: When planted around water bodies, it can help improve water quality by absorbing excess nutrients and pollutants.
    • Versatile Landscaping: This iris is suitable for various landscaping applications, including borders, water gardens, and as a specimen plant.
    • Low Maintenance: Once established, it requires minimal maintenance, which makes it suitable for gardeners of all skill levels.
    • Seasonal Interest: Provides seasonal interest with its striking spring and early summer blooms, and with its seed pods and foliage during fall and winter.
    • Wildlife Habitat: The plants can serve as a habitat and offer protection to various species of wildlife, particularly in aquatic environments.

  • 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

    • The Iris 'Sulphureux', also known as Yellow Iris, can be used in the art of fabric dyeing for achieving natural, earthy tones.
    • Yellow Iris fibers can be woven to create small baskets or mats, tapping into traditional crafting techniques.
    • Ink prepared from Yellow Iris can be used in eco-friendly printmaking or natural inks for fountain pens.
    • The plant can serve as an educational tool in schools for teaching students about pollination and plant biology.
    • The Yellow Iris can be used in floral art or Ikebana, the Japanese art of flower arrangement, for its distinct form and color.
    • Dried Yellow Iris plants can be used to create potpourris or natural air fresheners for home use.
    • Photographers and painters might often use the striking appearance of the Yellow Iris as a subject for artistic projects.
    • Yellow Iris petals can be added to handmade paper to create a decorative and textured finish.
    • The strong, vertical growth habit of the Yellow Iris can be used in garden design to create visual contrast with low-lying plants.
    • Yellow Iris can be planted in outdoor ponds to encourage biodiversity by providing habitat and food for insects and amphibians.

Interesting Facts

  • bedFeng Shui

    The Iris is not used in Feng Shui practice.

  • aquariusZodiac Sign Compitability

    The Iris is not used in astrology practice.

  • spiralPlant Symbolism

    • Royalty: Iris is often associated with royalty and regal bearings due to its striking appearance and history of being featured in royal emblems.
    • Wisdom and Valor: In Greek mythology, Iris was a goddess who personified the rainbow and acted as a messenger of the gods, symbolizing a bridge between heaven and earth and embodying wisdom and valor.
    • Faith and Hope: The varied colors and unique patterns of the iris suggest a sense of optimism, making it symbolic of hope and faith in various cultural contexts.
    • Purity: White irises, in particular, are often associated with purity and innocence, which may extend to the symbolic meanings of other varieties.
    • Spiritual Enlightenment: Due to its name and association with the celestial, the iris can represent heightened awareness or spiritual states.

Every 7-10 days
2500 - 10000 Lux
Every 2-3 years
Spring to Summer
As needed
  • water dropWater

    Tall Bearded Iris, commonly known as Iris 'Sulphureux', should be watered deeply to encourage deep root growth, but the frequency depends on the climate and soil conditions. During the growing season, water approximately every week or two, providing about one inch of water each time which is roughly 0.623 gallons per square yard. Make sure the soil drains well, as standing water or constant wetness can cause root rot. Reduce watering after the blooming period and allow the soil to dry out slightly between watering sessions in the fall.

  • sunLight

    Tall Bearded Iris prefers full sun to thrive, requiring at least six hours of direct sunlight each day. The ideal spot is a sunny border where they can receive uninterrupted daylight. However, in extremely hot climates, some afternoon shade can be beneficial to prevent the flowers from fading too quickly.

  • thermometerTemperature

    Tall Bearded Irises, including Iris 'Sulphureux', are hardy and can withstand a wide temperature range, from winter lows of approximately -20°F to summer highs up to 90°F. The ideal growing temperature for these irises is between 55°F and 75°F, which promotes healthy growth and optimal flowering. They can tolerate the occasional temperature extremes but should be protected from prolonged periods of heat or cold that fall outside their ideal range.

  • scissorsPruning

    Pruning Tall Bearded Iris involves removing the spent flower stalks to keep the plants looking tidy and to prevent seed production, which can divert energy from rhizome growth. After blooming, cut the flower stalks down to the base. In late summer or early fall, trim the foliage into a fan shape about 4 to 6 inches high to prepare for winter. Remove any damaged or diseased leaves as needed through the season to maintain plant health.

  • broomCleaning

    As needed

  • bambooSoil

    The ideal soil mix for Bearded Iris (Iris 'Sulphureux') should be well-draining yet maintain some moisture. A mix of loamy garden soil, sand, and compost is recommended for optimal growth and flowering. Bearded Iris varieties prefer slightly acidic to neutral soil, with an ideal pH range of 6.8 to 7.0.

  • plantRepotting

    Bearded Iris (Iris 'Sulphureux') typically doesn't need frequent repotting. It's best to divide and repot this plant every 3 to 5 years to prevent overcrowding and to rejuvenate its vigor.

  • water dropsHumidity & Misting

    Bearded Iris (Iris 'Sulphureux') thrive best in outdoor conditions where humidity is naturally regulated. They typically do not require high humidity and are tolerant of a range of conditions.

  • pinSuitable locations

    • Indoor

      Ensure bright light and well-draining soil mix.

    • Outdoor

      Plant in full sun, well-drained soil, provide space to spread.

    • Hardiness zone

      3-9 USDA

  • circleLife cycle

    The plant Iris 'Sulphureux', also known as Pale Yellow Iris, starts its life cycle as a seed that germinates in late winter to early spring, with new growth emerging from rhizomes. As temperatures rise in spring, foliage grows into strap-like leaves that form a fan-like shape. By late spring to early summer, the Iris 'Sulphureux' produces pale yellow flowers that bloom atop tall stems, attracting pollinators to facilitate cross-pollination. After flowering, the plant sets seed capsules that dry and split open in late summer, dispersing seeds for the next generation. Throughout the growing season, the rhizomes continue to expand underground, giving rise to new shoots and increasing the clump size, which gardeners may divide every few years to maintain plant vigor and health. As winter approaches, the plant goes into dormancy, with the foliage dying back, and the cycle begins anew the following spring.

  • sproutPropogation

    • Propogation time

      Spring to Summer

    • Propogation: Iris 'Sulphureux', commonly known as the sulphur yellow iris, is best propagated by division, a method that should be performed after flowering has ended, typically late summer to early fall. To propagate by division, carefully dig up the rhizomes and gently separate them, ensuring that each section has at least one fan of leaves and a portion of the root system. Trim the leaves to about one-third of their original height, which is typically to 6 to 8 inches (15 to 20 centimeters), to reduce water loss and make handling easier. Then, replant the divisions at the same depth they were originally grown, spacing them around 12 to 24 inches (30 to 60 centimeters) apart to allow adequate room for growth. Water the newly planted divisions thoroughly to help establish them. This straightforward technique allows gardeners to expand their iris collections and rejuvenate older clumps, encouraging more vigorous growth and a better floral display in the subsequent season.