Annual sunflowers get all the attention. There's no denying they can be show stoppers, but the annual sunflowers and their cousins, the false sunflowers, Heliopsis, are not slouches either.
Heliopsis are smaller, clumping plants with yellow, daisy-like flowers that bloom in great abundance and for up to 3 months. Deadheading improves the plants overall appearance, but doesn't seem to matter much for the amount of blooms you get. The major maintenance required with Heliopsis helianthoides is periodic division every 3-5 years, to keep the clump in control ad blooming freely. They can also tend to flop, especially after a rain, and staking keeps the clump tighter.
Heliopsis helianthoides (False Sunflower) 'Karat' - Oxeye Sunflower (USDA Zones 3 - 9, 3-4' x 2-3', Yellow Blooms: Repeat Bloomer)
- Helianthus salicifolius - Willowleaf Sunflower (USDA Zones 3 - 9, 3-5' x 3-4', Yellow Blooms: Mid- to Late Summer)
- Rudbeckia fulgida (Black-Eyed Susan, Orange Coneflower) 'Goldsturm' - (USDA Zones 3 - 9, 2' x 2', Yellow Blooms: Repeat Bloomer)