Blue Milkweed Tweedia coerulea

☠ Toxic to humans
🐾 Toxic to pets
🌸 Blooming
🍪 Not edible
‍🌱 Easy-care
blue tweedia


Tweedia coerulea, commonly known as blue milkweed or star of the Argentine, is a captivating plant renowned for its distinctive floral hue. The charm of this plant lies in its striking flowers that exude a sky blue or light blue color, a rarity among blossoms, which often captivate the onlookers with their star-shaped form. Petals of these enchanting flowers are velvety to the touch, radiating from the center like spokes on a wheel in a quintet that symmetrically enhances the plant's aesthetic. The leaves of blue milkweed are a lush shade of green and have a generally elongated, oval shape. They grow opposite each other along the stems, creating a sense of balance and structure in the foliage. The leaves may have a slightly hairy or fuzzy texture, adding to the tactile experience of the plant. In contrast to the softness of the leaves, the stems of blue milkweed exhibit a firmness and may display a subtle, grayish tone that complements the greenery. As the seasons change, blue milkweed might also bear fruits that take on a pod-like form. These edible pods are typically elongated and will split open when mature, revealing seeds that are ready to be dispersed by the wind. Overall, the blue milkweed distinguishes itself with its unique blue flowers and structured green foliage, making it a desirable addition to gardens and outdoor spaces seeking a touch of distinctive color and texture. Its visual appeal is heightened by its rare flower color, which is often sought after by garden enthusiasts and admirers of unique plants.

Plant Info
Common Problems

About this plant

  • memoNames

    • Family


    • Synonyms

      Blue Milkweed, Blue Flowered Milkweed, Blue Star Milkweed, Oxypetalum coeruleum, Star of the Argentine.

    • Common names

      Oxypetalum coeruleum, Oxypetalum caeruleum.

  • skullToxicity

    • To humans

      The plant known as blue milkweed may possess toxic properties, but there is limited information available on its specific effects on humans. It is related to the milkweed family, which contains other plants known to have toxic sap that can cause skin irritation and, if ingested, more serious symptoms such as nausea, vomiting, weakness, and in severe cases, potentially harmful effects on the heart. It is advisable to handle the plant with care and prevent ingestion to avoid any potential toxicity.

    • To pets

      The plant known as blue milkweed is potentially toxic to pets due to the presence of cardenolides, which are toxic compounds found in some members of the milkweed family. If ingested by pets, symptoms of poisoning may include vomiting, diarrhea, lethargy, and in severe cases, cardiac irregularities or failure. Immediate veterinary attention is recommended if a pet has consumed this plant.

  • infoCharacteristics

    • Life cycle


    • Foliage type


    • Color of leaves


    • Flower color


    • Height

      2-3 feet (0.6-0.9 meters)

    • Spread

      2-3 feet (0.6-0.9 meters)

    • Plant type


    • Hardiness zones


    • Native area

      South America


  • money-bagGeneral Benefits

    • Ornamental Value: Tweedia coerulea, commonly known as Blue Milkweed, adds unique beauty to gardens with its pastel blue, star-shaped flowers.
    • Attracts Pollinators: The bright flowers are known to attract butterflies and bees, supporting local ecosystems.
    • Drought Tolerance: Blue Milkweed is drought-tolerant once established, making it suitable for xeriscaping and low-water gardens.
    • Easy Propagation: The plant can easily be propagated from seeds or cuttings, allowing gardeners to share and distribute the plant with ease.
    • Deer Resistance: Tweedia coerulea is generally not preferred by deer, thus it's less likely to be damaged in areas with deer populations.
    • Container Gardening: It is suitable for container gardening, providing flexibility for people with limited garden space.
    • Textural Contrast: The fuzzy, gray-green foliage provides interesting textural contrast to other garden plants.
    • Long Blooming Season: Blue Milkweed has the advantage of a long blooming season, offering flowers throughout summer and sometimes into fall.
    • Historical Interest: The unique blue color has been admired over time and sometimes featured in historical and botanical art collections.

  • 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

    • Tweedia coerulea, commonly known as Blue Milkweed, can be used as a natural dye, offering a wide range of colors from its various plant parts for textiles or art projects.
    • The unique star-shaped blooms of Blue Milkweed make for an attractive addition to flower arrangements and bouquets, especially appreciated for their striking blue hue.
    • The plant's stems contain fibrous material that can be explored for use in paper making or for crafting natural textiles.
    • Because of its distinctive color, Blue Milkweed can be used as a teaching tool in educational settings for plant biology or natural pigment studies.
    • The silky texture of the plant's foliage can be used as an inspiration or material in designing patterns for fabrics or interior decorations.
    • In regions where Blue Milkweed is native, it can be used in habitat restoration and conservation projects to support local ecosystems and pollinator populations.
    • Blue Milkweed can serve as a natural insect attractant in gardens, helping to maintain a diverse and balanced garden ecology.
    • The plant's rapid growth and prolific seeding can be utilized in erosion control efforts, particularly on slopes or areas with poor soil stability.
    • Cultivated as a curiosity or novelty plant, Blue Milkweed can be used in educational gardens or botanical collections to showcase plant diversity.
    • Blue Milkweed's flowers can be used in perfumery, to capture the plant's subtle scent and create unique, nature-inspired fragrances.

Interesting Facts

  • bedFeng Shui

    The Blue Milkweed is not used in Feng Shui practice.

  • aquariusZodiac Sign Compitability

    The Blue Milkweed is not used in astrology practice.

  • spiralPlant Symbolism

    • Tranquility: The serene blue color of Tweedia coerulea, also known as Blue Milkweed, often symbolizes peace and calmness, evoking a sense of tranquility.
    • Rarity and Uniqueness: The uncommon blue shade in the floral world makes this plant a symbol of uniqueness and rarity.
    • Communication: Blue is a color generally associated with communication, and Blue Milkweed may symbolize the desire to convey one's thoughts and feelings clearly.

Every 1-2 weeks
2500 - 10000 Lux
Every 2-3 years
As needed
  • water dropWater

    Blue Milkweed should be watered when the top inch of soil feels dry, which typically means watering once every 5 to 7 days during the active growing season. Reduce the frequency of watering to every couple of weeks during the winter when the plant's growth slows down. Each watering should be thorough, providing enough water to moisten the soil all the way through to the bottom of the pot. Depending on the size of the pot, this may equate to around 16 to 32 ounces of water. Avoid waterlogging the soil as this can lead to root rot, and ensure the pot has good drainage.

  • sunLight

    Blue Milkweed thrives best in full sun to partial shade conditions. Ideally, it should receive at least 6 hours of direct sunlight each day. A spot near a south-facing window where it can get plenty of bright but indirect light is a good choice for indoor plants. However, if you live in an area with scorching summer sun, provide the plant with some afternoon shade to prevent leaf burn.

  • thermometerTemperature

    Blue Milkweed prefers warm temperatures and doesn't tolerate frost well. It can survive in temperatures as low as 30°F but it is ideal to keep it in conditions where temperatures do not drop below 50°F. The optimum temperature range for Blue Milkweed is between 60°F and 80°F. Protect the plant from sudden temperature drops and drafts, which can cause stress.

  • scissorsPruning

    Pruning Blue Milkweed is important for maintaining its shape and encouraging bushier growth. Prune the plant in the early spring, before the onset of new growth, by cutting back the stems to about half their length. Deadheading, or the removal of spent flowers, can also be done throughout the blooming season to promote continuous flowering. Pruning should be done annually to keep the plant healthy and well-groomed.

  • broomCleaning

    As needed

  • bambooSoil

    Blue Star (Tweedia coerulea) thrives in well-draining soil with a mix of potting soil, perlite, and peat. Aim for a slightly acidic to neutral pH of 6.0 to 7.0. A nutrient-rich soil encourages vibrant blooms.

  • plantRepotting

    Blue Star should be repotted every couple of years or when it becomes root-bound. Generally, repotting in the spring is ideal to give the plant time to establish in the new container.

  • water dropsHumidity & Misting

    Blue Star prefers moderate humidity levels, but as it's tolerant to different humidity conditions, it can adapt to indoor environments without requiring specific humidity adjustments.

  • pinSuitable locations

    • Indoor

      Place Blue Star in a bright, sunny spot indoors to encourage flowering.

    • Outdoor

      Plant Blue Star in full sun to part shade with protection from harsh elements.

    • Hardiness zone

      9-11 USDA

  • circleLife cycle

    Tweedia coerulea, commonly known as blue milkweed or dayflower, begins its life cycle as seeds that germinate in warm soils. Once sprouted, the seedlings develop into young plants with characteristically fuzzy leaves. As it matures, the plant forms a bushy structure and, under suitable conditions, produces clusters of distinctive sky-blue, star-shaped flowers. Following pollination, typically by insects, these flowers give way to elongated seed pods that contain the plant's flat, brown seeds. Upon maturity, the seed pods split open to release the seeds, which can disperse to start the next generation. Finally, in regions with colder climates, Tweedia coerulea may die back to the ground in winter, only to resprout from its root system come spring.

  • sproutPropogation

    • Propogation time


    • The most popular method of propagation for Blue Milkweed (Tweedia coerulea) is by sowing seeds. The ideal time for propagation by seeds is late winter to early spring, just before the last frost date, when temperatures start to warm. To propagate, the seeds should first be soaked in warm water overnight to soften the tough outer coating. Afterwards, they are sown shallowly, about 1/8 inch (approximately 3 mm) deep, in well-draining soil and kept moist but not wet. It's important to provide them with plenty of light and warmth, ideally around 70 degrees Fahrenheit (about 21 degrees Celsius), for germination, which typically takes between 10 to 20 days. Seedlings can be transplanted outdoors once the danger of frost has passed and they are large enough to handle.