Culture
Easily grown in average, medium to moist, well-drained soils in full sun. Established plants tolerate some light shade and drought. Plants generally tolerate a variety of soils including both clay and sandy loams as long as drainage is good. Plants also tolerate poor, rocky soils and urban conditions. Plant seed in the garden after last spring frost date. Best to site plants in locations sheltered from strong winds. Plant foliage often depreciates as the summer progresses. Removal of browned and tattered seed heads, foliage and plant stalks from the garden after bloom may improve the appearance of the landscape, but often becomes a great disappointment to local bird populations that love to feed on the seeds. If the plants must come down, consider saving the seed heads for feeding the birds in winter. Plants will self-sow in the garden.
'Happy Days' is best grown in consistently moist, well-draining soils and does not exhibit particularly high tolerance for drought, clay soils, or rocky soils.
Noteworthy Characteristics
Helianthus is a genus of about 60-70 species of annuals and perennials from North America, Central America, Peru and Chile. Commonly called sunflowers, they are grown for their bright, yellow (occasionally red) flowers.
Genus name comes from the Greek words helios meaning sun and anthos meaning flower.
Flower heads tend to follow the path of the sun each day from morning to night, hence the common name.
'Happy Days' is a perennial, hybrid sunflower selection that features 3.5-4" wide, golden yellow, double blooms on well-branched stems. Mature plants can reach around 2' tall and 1.5' wide. The double flowers do not provide as many benefits to wildlife and pollinators compared to single or semi-double selections.
Problems
Rust, leaf fungal spots and powdery mildew are somewhat common. Caterpillars and beetles often chew on the foliage. Watch for Sunflower Headclipping Weevil (Haplorhynchites aeneus) in July.
Uses
Small groups or mass. Borders, cottage gardens, bird gardens, wildflower, or native plant gardens. Good fresh cut flower.