Helianthus angustifolius
TAXONOMY
FamilyAsteraceae
GenusHelianthus
Zone5
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Plants of the World OnlineABOUT
Helianthus angustifolius, commonly known as the Swamp Sunflower, is a perennial plant native to the southeastern United States. It belongs to the Asteraceae family and is known for its bright yellow flowers that bloom in late summer to fall. The plant thrives in wetland areas and can grow up to 6 feet tall. It has a dormancy period during the winter months.
ALSO KNOWN AS
Coreopsis Angustifolia
Leighia Bicolor
Narrow-Leaf Sunflower
Narrow-Leaved Sunflower
Rudbeckia Angustifolia
Swamp Sunflower
Discomela angustifolius
Helianthus angustifolius subsp. angustifolius
Helianthus angustifolius var. angustifolius
Helianthus angustifolius var. planifolius
OVERVIEW
VPDCalculate
WaterWet
SoilLoamy
LightDirect Bright (6 Hours)
Temperature25° C
Humidity60%
GDD1,800
Dormancy3 Months
pH6.5
Pressure1,013 mbar
DETAILS
Care Instructions
Swamp Sunflowers require full sun to thrive and should be planted in an area that receives at least six hours of direct sunlight daily. They prefer moderate temperatures and high humidity. Water the plant regularly to keep the soil evenly moist, especially during dry periods. The plant can tolerate a range of temperatures but performs best in warm conditions.Harvest
Helianthus angustifolius, commonly known as the narrowleaf sunflower, is typically harvested in late summer to early fall when the flowers are fully open and the seeds have matured. To harvest, cut the flower heads off the plant using sharp scissors or pruning shears, leaving a few inches of stem attached. Allow the flower heads to dry in a well-ventilated area away from direct sunlight. Once dried, the seeds can be easily removed by rubbing the flower heads. Ensure the seeds are completely dry before storing them in a cool, dry place to prevent mold and spoilage.Soil
Helianthus angustifolius prefers loamy soil that is well-draining yet retains moisture. The soil should be rich in organic matter to support the plant's nutrient needs. Ensure the planting site has good drainage to prevent waterlogging, which can harm the plant.Fertilizer
Use a balanced fertilizer with an N-P-K ratio of 10-10-10. Fertilize the plant in early spring and again in mid-summer to support its growth and flowering. Avoid over-fertilizing, as this can lead to excessive foliage growth at the expense of flowers.Repotting
If growing in a container, repot the Swamp Sunflower every 1-2 years to refresh the soil and provide more space for root growth. Choose a slightly larger pot with good drainage. Repot in early spring before the growing season begins.Propagation
Propagate Helianthus angustifolius through seeds or division. Sow seeds in early spring or divide mature plants in late spring or early summer. Ensure the divisions have several healthy shoots and roots before replanting.Pruning
Prune the plant in late winter or early spring to remove dead or damaged stems and encourage new growth. Deadhead spent flowers during the blooming season to promote continuous flowering and prevent self-seeding.Toxicity
Helianthus angustifolius is not toxic to pets or humans. All parts of the plant are considered safe, making it a good choice for gardens frequented by children and animals.Additional
Swamp Sunflowers are excellent for attracting pollinators such as bees and butterflies to the garden. They can also be used in naturalized areas or rain gardens due to their preference for moist conditions.REVOLUTIONIZE YOUR PLANT CARE
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